The forward deployed engineer interview, round by round

By FDE Interview Prep, a SourceStrongAI company

On this page22 sections

1. What the loop tests
2. The recruiter screen
3. The hiring manager interview
4. The coding round
5. Enterprise system design
6. The decomposition round
7. Learning and re-engineering
8. The client role-play
9. Behavioral questions
10. AI systems and evaluation
11. The take-home
12. SQL and data questions
13. A failing system
14. What employers publish and what candidates report
15. AI rules by company
16. What no one publishes
17. Pick a prep plan
18. Common mistakes
19. Every post in this guide, by the question you have
20. Start with the customer side
21. Questions people ask
22. Keep reading

You have an FDE interview on the calendar, and the only descriptions of the loop you can find contradict each other. One says it is LeetCode, another says it is all customer role-play, and another quotes a pass rate nobody can source.

The short answer: an FDE interview tests two things: can you build and fix real systems, and would a customer trust you in the room. Loops are assembled from these parts, in a mix that changes by company:

• a recruiter screen
• a hiring-manager deep dive
• coding, algorithmic or practical
• enterprise system design
• decomposition, an open-ended customer problem
• learning and re-engineering, in Palantir loops
• a client role-play
• behavioral questions about customer work
• AI systems and evaluation, in AI roles
• a take-home, in some loops
• SQL and data questions
• a failing system to debug

For each round, this guide separates what employers publish from what candidates report, and gives you the words to say.

Headed to an AI lab or an AI product company? Start with AI systems and evaluation, the take-home and enterprise system design. Headed to an enterprise software or data company, such as Palantir or Databricks? Start with decomposition and SQL and data questions, and for Palantir add learning and re-engineering.

Know your company already? Jump to what Palantir, Google, OpenAI, Anthropic, Sierra, C3 AI, Databricks and Salesforce publish.

What the loop tests

Every round is checking one side of a double bar. Can you write, debug and design software to the standard of a good engineer? And can you take a vague, political, badly specified customer problem and turn it into something shipped, while keeping the customer’s trust?

Ramp’s blog says its FDE hiring checks coding, debugging, data structures and system design as a bar to pass. ^[1]Source 1Forward Deployed EngineeringPublisherRamp Builders (engineering blog)Source typecompany blog Ramp’s Director of Engineering, Leo Mehr, said on the dearCC podcast in June 2026 that FDE candidates face the same technical bar and must pass the software engineering loop. ^[2]Source 2What is a Forward Deployed Engineer? (FDE Explained) feat. Leo Mehr of Ramp (YouTube auto-generated English captions)PublisherdearCC (Clara Shih), YouTubeSource typerecorded talk or interview That is the first bar, and Ramp’s blog says it avoids optimizing it further and does not over-index on perfection. ^[1]Source 1Forward Deployed EngineeringPublisherRamp Builders (engineering blog)Source typecompany blog So treat it as a bar to clear, not a score to maximize: once you clear it reliably, give the time you save to the customer side. The second shows up in rounds built around a customer: an open-ended problem, a role-play, a presentation to a mixed audience.

Palantir’s former FDE recruiting lead told First Round Review that its problem-solving interviews aimed to assess both business reasoning and technical reasoning. ^[3]Source 3So You Want to Hire a Forward Deployed EngineerPublisherFirst Round ReviewSource typenews report That sentence is the whole loop in miniature.

In Pro, our lesson on the double bar turns this into a self-diagnosis you can run in an evening. If you only read one thing before your loop, read the evidence map, which is free and shows how to tell a company’s own words from a stranger’s report.

Each round below says what employers publish about it, what candidates report, what a strong answer sounds like, and where to practice. Your loop will contain some of these, probably not all. Every round below ends with questions to practice, and every question shows its framework free.

The recruiter screen

The recruiter screen checks fit and logistics: why this role, why now, travel, level, location and pay expectations. It is short, but it sets the story every later interviewer hears.

What employers publish points at motivation and logistics. Palantir’s New Grad FDSE application asks candidates to confirm interest in FDSE rather than Software Engineer. ^[4]Source 4Apply: Forward Deployed Software Engineer, New Grad - Commercial (New York, NY) - Palantir on LeverPublisherPalantir Technologies (Lever)Source typecompany job posting Its US Government FDSE application form asks about clearance status and whether you support the advertised travel percentage and compensation range. ^[5]Source 5Apply: Forward Deployed Software Engineer - US Government (Washington, D.C.) - Palantir on LeverPublisherPalantir Technologies (Lever)Source typecompany job posting Ramp’s Leo Mehr said that asking candidates what they are excited about is one way Ramp decides whether someone suits FDE or another engineering role. ^[2]Source 2What is a Forward Deployed Engineer? (FDE Explained) feat. Leo Mehr of Ramp (YouTube auto-generated English captions)PublisherdearCC (Clara Shih), YouTubeSource typerecorded talk or interview

So “Why FDE and not software engineering?” is the question to have cold. A weak answer is about liking people or variety, which collapses the moment they ask “so why not product engineering?”. A strong one names work you have already done that looks like the job:

“In my current role I get pulled into customer integrations, and those are the weeks I do my best work: the problem is vague, the data is messy, and I can see the person whose day gets better. I want a job where that is the work, not the interruption, and where I still write the code myself.”

Practice it with why FDE and not software engineering, tell me about yourself in a minute and how much travel can you commit to.

The hiring manager interview

The hiring manager wants evidence you have owned something hard, end to end, in front of someone who depended on it. Expect a project deep dive and questions that keep asking “why”.

Palantir says onsite interviewers ask how candidates have executed, challenged themselves, motivated others and made judgments, and about past failures. ^[6]Source 6Getting Hired - Palantir CareersPublisherPalantir TechnologiesSource typecompany hiring page In its early-talent timeline, the hiring manager interview is customized based on onsite feedback. ^[7]Source 7Students | Palantir Careers (timeline image: RecruitingTimeline_V3.jpg)PublisherPalantirSource typecompany hiring page One candidate reported, in December 2025, a rejection a couple of hours after their Palantir hiring-manager round, and wrote that it was about mission alignment, not technical ability. ^[8]Source 8Palantir FDSE Full Interview Loop Process (post by u/Not_the_Sauron)PublisherReddit r/csMajorsSource typecandidate report on Reddit That is one person’s reading of one rejection, but it is cheap to guard against: prepare why this company’s work matters to you as carefully as you prepare your project.

The common failure is a tour of what “we” built. The interviewer cannot credit anything to you. Before the round, take your main project and write down three decisions that were yours alone, what you rejected, and what you would change. Then answer in this order: the decision, the options, why you chose, what happened.

Here is that order out loud, about a fictional project:

“The decision that was mine: I moved the customer’s import from one nightly batch to processing each file as it landed. The other option was a bigger batch window. I chose per-file because their finance team needed each file’s errors the same morning, not the next day. It fixed that, but month-end load arrived all at once, so next time I’d put a queue with backpressure in from the start.”

Notice what it does: one decision, the option you rejected, the reason in the customer’s terms, and a flaw you found yourself. The follow-up “why not the bigger window?” now has an answer waiting.

Practice with the project deep dive, which decisions were yours alone and your first month with a new customer, and then the hardest technical problem you have solved.

The coding round

FDE coding rounds split two ways, and you should prepare for both. Some look like any software engineering screen. Others are practical: a flaky API, a messy file, a bug in code you did not write.

Palantir’s guide says it will not ask about tricky or obscure features of a specific language, and it names Forward Deployed Software Engineers among those who need to understand quality code. ^[9]Source 9Writing Good CodePublisherPalantirSource typecompany hiring page It also says a core facet of a good coding interview is translating an algorithmic idea into working code, and it tells candidates to think about edge cases and how their code could break. ^[9]Source 9Writing Good CodePublisherPalantirSource typecompany hiring page It defines one interviewed competency as working within existing systems, codebases and infrastructure. ^[10]Source 10Working Inside Existing SystemsPublisherPalantirSource typecompany hiring page

Candidates report both styles. One candidate reported, in July 2026, that their Google FDE (L4) coding round was one roughly LeetCode-Medium question framed as a real-world scenario. ^[11]Source 11FDE Interview Experience at Google (L4)PublisherBlind (teamblind.com)Source typecandidate report on Blind One candidate reported, in November 2024, a LeetCode-medium hash-map problem on HackerRank CodePair in their Palantir FDSE screen. ^[12]Source 12Palantir Interview Process... So Far, FDSE 2024 (post by u/kircher32245)PublisherReddit r/csMajorsSource typecandidate report on Reddit One candidate reported, in August 2026, that their Google L5 FDE interviews had no LeetCode at all. ^{[13, 14]}Source 13Google FDE vs Remain Amazon SDEPublisherBlind (teamblind.com)Source typecandidate report on BlindSource 14Google L5 FDE vs Remain Amazon L5 SDEPublisherBlind (teamblind.com)Source typecandidate report on Blind

A practical problem you should be able to write without thinking is a rate limiter. The move to show is computing the refill from elapsed time on each call, instead of running a timer per user:

import time

class TokenBucket:
    def __init__(self, rate, cap, clock=time.monotonic):
        self.rate, self.cap = rate, cap
        self.clock = clock
        self.tokens, self.last = cap, clock()

    def allow(self, cost=1):
        if cost > self.cap:
            raise ValueError("cost exceeds cap")
        now = self.clock()
        gained = (now - self.last) * self.rate
        self.tokens = min(self.cap, self.tokens + gained)
        self.last = now
        if self.tokens < cost:
            return False
        self.tokens -= cost
        return True

Passing the clock in makes it testable without sleeping, and time.monotonic is used because, as the Python documentation for time.monotonic says, it is not affected by system clock updates. The first check is there because a cost bigger than the capacity can never pass: rejecting it up front is kinder than returning False forever.

Then say the follow-ups before they ask them. Threads first: “Inside one process with threads, I’d hold a lock around the refill and the spend, or two threads can both spend the last token.” Then servers: “With several servers, I’d keep the bucket in a shared store and do the read, refill and spend in one atomic step, for example a Redis script, for the same reason.” Redis’s scripting documentation says it guarantees a script runs atomically.

Read what FDE coding rounds test, which is free. Then practice the token bucket, a flaky, rate-limited API and a messy CSV export.

Enterprise system design

The enterprise system design round asks you to build something inside someone else’s environment, with their identity system, their data rules and their security team. It is not “design Twitter”.

One candidate reported, in July 2026, a Google FDE (L4) design round run as a role-play, with the interviewer as a company CTO. ^[11]Source 11FDE Interview Experience at Google (L4)PublisherBlind (teamblind.com)Source typecandidate report on Blind The same Blind report says the CTO wanted a smart AI-powered system, and the discussion covered requirements, scoping, architecture, deployment, scalability, security and evaluation. ^{[11, 15, 16]}Source 11FDE Interview Experience at Google (L4)PublisherBlind (teamblind.com)Source typecandidate report on BlindSource 15Google Forward Deployed Engineer Interview Experience (Blind)PublisherBlindSource typecandidate report on BlindSource 16Is Google FDE interview same as SWE? (Blind)PublisherBlindSource typecandidate report on Blind One candidate reported, in August 2026, that their Google L5 FDE loop included a system design interview specifically for agents, covering evals and guardrails. ^{[13, 14]}Source 13Google FDE vs Remain Amazon SDEPublisherBlind (teamblind.com)Source typecandidate report on BlindSource 14Google L5 FDE vs Remain Amazon L5 SDEPublisherBlind (teamblind.com)Source typecandidate report on Blind

The trap is a generic diagram: boxes for an API, a queue and a database, with no trust boundary and no permission check. Start instead with three questions to the “CTO”:

1. Who uses it, and what decision does it change?
2. What data may it touch, and where must that data stay?
3. What happens when it is wrong, and who finds out?

Then draw the smallest version that answers all three, and scale it only after. Out loud, the opening sounds like this:

“Before I draw anything: who’s the first user, and what do they do differently on day one? Can the documents leave your cloud account, or does everything run inside it? And when the system gets an answer wrong, who sees it first, your staff or your customers?”

Here is the smallest version for one prompt: question answering over a court’s documents. Say the answers come back like this: clerks are the users, nothing leaves the court’s cloud, and a wrong answer must be traceable.

• Where it runs: everything inside the court’s own cloud account, calling a model endpoint their security team approves.
• Who sees what: sign-in goes through their identity provider, and at query time retrieval only returns documents the user’s groups can already open.
• What is recorded: every question and every document returned goes to an audit log their security team can read.
• How you know it works: a small set of questions the clerks labeled is rerun before every change.

Four lines, and each one answers a question the “CTO” asked. That is the difference from a generic diagram.

Read why enterprise design is different, which is free, then practice RAG inside a court’s own cloud, SSO with same-day deprovisioning and an eval harness for a support agent.

The decomposition round

The decomposition round hands you a vague problem, such as reducing hospital readmissions, and watches how you break it down. There is no single right answer. There is a visible process.

Palantir defines the competency it calls Navigating Open-Ended Questions as tackling open-ended technical challenges that have several possible solutions with different trade-offs. ^[17]Source 17Palantir Careers | Navigating Open-Ended QuestionsPublisherPalantir TechnologiesSource typecompany hiring page Its interview advice is to articulate the alternatives and trade-offs, be pragmatic enough to reach a concrete approach, and deliver a functioning idea first, then expand it. ^[17]Source 17Palantir Careers | Navigating Open-Ended QuestionsPublisherPalantir TechnologiesSource typecompany hiring page Its recruiting blog tells intern and new-grad candidates to think out loud and share their questions and observations. ^[18]Source 18From Pipeline to Prospect: Insights and Advice from Palantir Recruitment (Palantir Blog; archived copy)PublisherPalantir Technologies (Palantir Blog on Medium)Source typearchived company page

Candidates name the round at Palantir and beyond it. One candidate reported, in December 2025, a Palantir round they called “Decomp”, which opened with behavioral questions before the technical work. ^[8]Source 8Palantir FDSE Full Interview Loop Process (post by u/Not_the_Sauron)PublisherReddit r/csMajorsSource typecandidate report on Reddit One candidate’s report on Aced, for a Databricks FDE role interviewed in February 2026, called the decomposition round the most important of their loop. ^[19]Source 19Databricks Forward Deployed Engineer Interview ExperiencePublisherAced (formerly Exponent)Source typecandidate’s personal write-up

Our method, which is ours rather than any employer’s rubric, runs in this order: clarify the goal and who owns it, pick one metric, list the inputs and who owns each, sequence by risk, build a walking skeleton, then name how it fails. The first minute sounds like this:

“Before I design anything: who asked for this, and what would they count as success in three months? Is it readmissions overall, or one condition? And which data do we have today, and who owns it?”

Say the answers narrow it to heart failure. The whole method, in six short lines:

• Goal and owner: fewer heart-failure patients back in hospital within a month, owned by the discharge team.
• Metric: that readmission rate, for one pilot ward.
• Inputs and owners: discharge records from the hospital’s records system, owned by IT.
• Riskiest first: whether those records arrive daily and complete, so check that before building anything on them.
• Walking skeleton: a daily list of high-risk discharges, handed to one nurse to call.
• How it fails: the list gets ignored, so measure calls made, not just the list.

In a real round, spend most of your time on the middle lines. The shape is the point: every step answers the one before it.

Read the method on one page, which is free, and our full decomposition interview guide. Then practice hospital readmissions, a feature from fitness-app data and factory downtime, or run a timed customer case free.

Learning and re-engineering

Palantir’s early-talent timeline names a learning interview beside decomposition in its virtual onsite. ^[7]Source 7Students | Palantir Careers (timeline image: RecruitingTimeline_V3.jpg)PublisherPalantirSource typecompany hiring page We found no Palantir page that names a re-engineering round. Its pages do define working within existing systems, codebases and infrastructure as an interviewed competency, and say developers spend far more time debugging, modifying and extending existing code than writing new code, which is the skill such a round would test. ^[10]Source 10Working Inside Existing SystemsPublisherPalantirSource typecompany hiring page

Candidates name the rounds too. One candidate reported, in December 2025, a Palantir loop with a decomp round and a learning round. ^[8]Source 8Palantir FDSE Full Interview Loop Process (post by u/Not_the_Sauron)PublisherReddit r/csMajorsSource typecandidate report on Reddit One Blind poster said, in February 2025, that their upcoming Palantir FDSE onsite had coding, decomposition and “reengineering” rounds. ^{[20, 21, 22]}Source 20Palantir FDSE virtual onsitePublisherBlind (teamblind.com)Source typecandidate report on BlindSource 21Palantir Forward Deployed Software EngineerPublisherBlind (teamblind.com)Source typecandidate report on BlindSource 22Palantir hm callPublisherBlind (teamblind.com)Source typecandidate report on Blind

The learning round teaches you something on the spot and watches you use it. What helps is showing your understanding as it forms: restate the idea in your own words, make up a tiny example, and check it with the interviewer before you build on it.

Say the interviewer teaches you a permission rule: a user sees a document if any of their groups is on its access list, unless the document is under legal hold. Out loud:

“So access is an OR across my groups, and legal hold overrides all of it. Which means an admin who is in every group still can’t open a held file. Is that the right picture?”

The made-up edge case is the point. It shows you have built a model of the rule, not memorized a sentence, and it gives the interviewer something to correct before you build on it.

The re-engineering round hands you code you did not write. Do not start editing. Start here:

“Let me restate what this function is supposed to do, then run it on the smallest input before I change anything.”

Then, in order: reproduce the bug with the smallest input, write it down as a failing test, make the fix, and only then extend the code. Narrate each step, because the interviewer is watching how you find your way in, not only whether you get out.

For the full picture, read the re-engineering interview and the learning interview, then practice debugging unfamiliar code and reproducing a bug as a test.

The client role-play

In a client round, the interviewer plays a customer: a CTO who wants a date, a PM adding scope, a VP asking why the AI got it wrong. It tests whether you can hold a hard conversation without promising what you cannot deliver.

The formats employers publish that we found are working sessions and case studies, not live role-plays. Sierra’s onsite, for engineering roles generally rather than an FDE title, starts with a Plan session where the candidate drives ideation of a product while interviewers ask questions, and ends with a Review where product choices are debated. ^[23]Source 23The AI-native interviewPublisherSierraSource typecompany blog Attio’s Forward Deployed GTM Engineer posting lists a case study interview and panel interviews with stakeholders, without describing the case. ^[24]Source 24Forward Deployed GTM Engineer @ AttioPublisherAttio (Ashby job posting)Source typecompany job posting

The live role-play comes from candidates. One candidate reported, in July 2026, that in their Google FDE (L4) loop the interviewer acted as a company CTO. ^[11]Source 11FDE Interview Experience at Google (L4)PublisherBlind (teamblind.com)Source typecandidate report on Blind One candidate’s report on Aced for a Cognition FDE role, dated April 2026, describes final rounds that felt like simulated customer work, with executive pitches and a fake-company case. ^[25]Source 25Cognition AI Forward Deployed Engineer Interview ExperiencePublisherAced (formerly Exponent)Source typecandidate’s personal write-up

The move that works is to lead with the thing they need, then the reason. If the project is three weeks late, the first sentence is the new date and the plan, not the cause:

“The new date is the last Friday of next month. The single sign-on piece slipped: your identity team’s test tenant arrived later than we planned, and I should have flagged that risk sooner. On the original date, your pilot group will have ingestion and search working behind a temporary login. The one decision I need from you this week: do we start the pilot on that temporary login, or hold it until sign-on is done?”

Notice the order: the date, the cause in one line with your own part in it, what they still get, and one decision with a deadline.

Read what customer rounds look like, which is free. Then practice telling the CTO you will be three weeks late, scope creep from a customer’s PM and explaining to a VP why AI makes mistakes.

Behavioral questions

Palantir says its onsite interviewers ask about past failures. ^[6]Source 6Getting Hired - Palantir CareersPublisherPalantir TechnologiesSource typecompany hiring page In an FDE loop, the stories worth preparing are customer ones: an escalation you owned, a customer who needed something your product team refused, a failure that was yours. Salesforce’s How We Hire page says hiring teams may ask behavioral, competency-based or situational questions, as company-wide guidance. ^[26]Source 26How We Hire at SalesforcePublisherSalesforce CareersSource typecompany hiring page

Run an ownership audit on each story before you tell it: circle every “we” and ask whether it was you. Keep the situation to two sentences, spend most of the answer on what you decided and did, and end with a measured result and what you would do differently. A fictional example, compressed:

“A customer’s nightly sync started dropping records just before their audit, and their admin had escalated with no reply. I took the ticket and promised a cause or a plan by end of day.

I found their schema change had broken our field mapping. I decided against a silent patch and shipped a validator that fails loudly, then walked their admin through it on a call.

Every record reconciled against their ledger before the auditors arrived, and the validator now ships to every customer. Next time I’d add the alert before a customer’s deadline, not during it.”

The middle carries the weight: “I took”, “I found”, “I decided”. The result is something you could check.

Practice a customer escalation you owned, a failure that was yours and a project you owned end to end.

AI systems and evaluation

At AI companies, and at enterprise companies that deploy AI, you may get a round on AI systems and evaluation: retrieval, agents, prompt injection and, above all, “how do you know it works?”.

The job side is clear. Anthropic’s FDE posting lists evaluation frameworks among its qualifications. ^[27]Source 27Forward Deployed Engineer (London)PublisherAnthropic (Greenhouse)Source typecompany job posting OpenAI’s Forward Deployed Engineer (Healthcare) posting lists defining evaluations and launch criteria against customer-specific acceptance thresholds as a responsibility. ^[28]Source 28Forward Deployed Engineer (FDE), Healthcare - SFPublisherOpenAI (Ashby)Source typecompany job posting On the interview side, one candidate reported, in August 2026, a Google L5 FDE design interview for agents that covered evals and guardrails. ^{[13, 14]}Source 13Google FDE vs Remain Amazon SDEPublisherBlind (teamblind.com)Source typecandidate report on BlindSource 14Google L5 FDE vs Remain Amazon L5 SDEPublisherBlind (teamblind.com)Source typecandidate report on Blind

A strong answer to “how do you know it works?” names evidence, not tools: a golden set of real cases the customer labeled, a metric tied to the decision the system supports, a regression run before every prompt or model change, and a sample of production traffic reviewed by a person each week. Said out loud:

“I’d start with a set of real cases the customer’s own team labeled, including the ones they’d be embarrassed to get wrong. The metric follows the decision: for a support agent, whether the answer resolved the ticket without a human. Every prompt or model change reruns that set before it ships, and each week I review a sample of live answers with someone on their team.”

Then say what you would do when the numbers disagree with the customer’s gut: pull the cases they are worried about into the set, so the disagreement becomes something you can measure.

If the round is about agents, the guardrails are the design. Say them in one breath:

“The agent gets an allowlist of tools, each with the narrowest credential that works. Anything it can’t undo, like a refund or an email to a customer, waits for a person to approve. It has a budget of steps and cost, and when it runs out it hands the case to a person with a note of what it tried.”

The agentic system design interview goes further: stuck agents, hand-off and what to log.

Practice how do you know your AI system works, defending a support agent from prompt injection and fine-tuning vs RAG vs prompting.

The take-home

Some loops replace or add to live coding with a take-home, then ask you to walk through it. Others ask for a presentation. Databricks’ general careers page, as company-wide guidance, says a presentation is required for some roles, particularly go-to-market and executive ones. ^[29]Source 29Our hiring process / Interview prepPublisherDatabricks CareersSource typecompany hiring page One candidate’s report on Aced for a Cognition FDE role, dated April 2026, describes presenting a real technical project to people at different levels. ^[25]Source 25Cognition AI Forward Deployed Engineer Interview ExperiencePublisherAced (formerly Exponent)Source typecandidate’s personal write-up

OpenAI’s guide says its assessment formats vary by team and may include take-home projects. ^[30]Source 30Interview Guide | OpenAI (read through the r.jina.ai reader proxy; a direct fetch returned 403)PublisherOpenAISource typecompany hiring page Sierra’s onsite has the candidate build for two hours with AI tools of their choice, then demo the work, followed by a debate of product choices and a code review. ^[23]Source 23The AI-native interviewPublisherSierraSource typecompany blog Ethyca says a submitted solution is walked through on an interview call. ^[31]Source 31Ethyca Technical Challenge -- Forward Deployed Privacy Engineer (FDPE)PublisherEthyca (GitHub)Source typecompany website

Published briefs show how customer-shaped these get. One candidate reported, in a repository created in September 2026, a Kong take-home that opened with a kickoff call where the interviewer plays a customer stakeholder and ended with a live readout. ^[32]Source 32Kong PS / Forward Deployed Engineer — Take-Home ExercisePublisheralexscottan (GitHub)Source typecandidate’s take-home repository

Scope it like a customer project: write the three things it must do in the first ten minutes, build those end to end, and keep a list of what you chose not to build and why. That list becomes the best part of your walkthrough. For a fictional support-search brief, it might read:

• Accounts and login: not built. The brief never mentions users, and a hard-coded key keeps the demo honest.
• Retries on the upstream API: not built. Failures are logged with the request, and backoff is the first thing I’d add.
• A web interface: not built. The reviewer runs it from a terminal, so the effort went into the output they will read.

Each line shows a decision, not a gap. Practice what you would change in your take-home, defending your take-home design and presenting a past project to a mixed audience.

SQL and data questions

Data questions can come inside a coding screen or an assessment rather than as a round of their own. One commenter in a Salesforce Agentforce FDE thread reported, in August 2026, basic SQL in their assessment. ^[33]Source 33Forward Deployed Engineer (Agentforce) (comment by u/joemons)PublisherReddit r/SalesforceCareersSource typecandidate report on Reddit One candidate for a Palantir FDSE (Gov) role reported, in August 2025, that learning SQL was the hardest part for them, having never used it before. ^[34]Source 34Palantir Forward Deployed Engineer Interview ExperiencePublisherAced (formerly Exponent)Source typecandidate’s personal write-up

A classic trap in customer data is the join that fans out. Take a fictional table of orders and a table of support tickets, where one order can have several tickets. You want the revenue from orders that had any ticket:

-- wrong: one row per ticket
SELECT SUM(o.amount)
FROM orders o
JOIN tickets t
  ON t.order_id = o.id;

-- right: one row per order
SELECT SUM(amount)
FROM orders
WHERE id IN (
  SELECT order_id FROM tickets
);

With orders of 100 and 50, two tickets on the first order and one on the second, the join returns 250 and the second query returns 150. The join counted the first order twice. Say this before you write the sum: “Before I sum, I check the grain: one row per order or one per ticket?”

Know window functions too, for running totals and “latest row per group”. Practice join fan-out that inflates revenue, a running total per customer and the latest status per ticket.

A failing system

Sometimes the technical problem is a live one: something a customer runs is failing, and you have to find out why. One candidate reported, in January 2026, that the recruiter for a Palantir Forward Deployed Enablement Engineer role described a technical interview troubleshooting a data pipeline in Python. ^[35]Source 35Anyone have tips to prepare for Palantir Forward Deployed Enablement Engineer - Customer Success Interview? (post by u/Appropriate-Bird-513)PublisherReddit r/csMajorsSource typecandidate report on Reddit

The first hour on “our requests are failing” has an order. Scope before you guess:

1. Which requests, and since when? All of them, one endpoint, one customer?
2. What do the errors say? A wall of 429 is a limit. A 401 is credentials, such as an expired or rotated key, and a 403 is permissions, such as a missing scope. A 502 or 504 comes from a proxy or gateway: the service behind it sent a bad reply or took too long. A 500 is the service itself failing, and a 503 says it is overloaded or down for maintenance. Each sends you somewhere different.
3. What changed? A deploy, a config, a certificate, the customer’s own traffic.
4. Stop the bleeding, then find the cause. Roll back or rate-limit first if customers are hurting.

The words to open with: “Before I touch anything, I want to know which requests are failing, since when, and what the status codes are. Then I’ll ask what changed around that time.”

If it is a pipeline rather than an API, as in that Palantir report, the opening question changes: “Which run first went wrong, and what were the row counts at each stage for that run and the one before?” Then check, in order:

1. Counts per stage, to find where rows vanish or multiply.
2. The source schema and types, for a column that was renamed, retyped or dropped.
3. The input files, for ones that arrived late, went missing or arrived twice.
4. Whether a rerun is safe: it should overwrite its partition, not append to it, or the fix doubles the data.

Practice failing API requests in the first hour, a retry storm and a duplicate webhook.

What employers publish and what candidates report

Two kinds of source describe FDE interviews, and they are not equal. An employer’s careers page or posting tells you what the company commits to in writing. A candidate’s post on Blind or Reddit tells you what one person says happened, once, for the role they named. Read both, and never mistake the second for the first.

The pattern across the eight companies below: the company publishes the shape, candidates report the content, and neither gives you the scoring.

C3 AI has two accounts worth reading side by side. One candidate reported, in August 2026, an AI interview and then a CodePair coding round for a C3 AI FDE role, and said the process ended before a system design round. ^[40]Source 40C3 AI - Forward Deployed Engineer interview process (comment by u/BalanceOdd144)PublisherReddit r/leetcodeSource typecandidate report on Reddit A second candidate reported, in August 2026, an AI-based screening, then coding and system design rounds back to back, then a behavioral interview with a director. ^[41]Source 41C3 AI Senior Forward Deployed Engineer (FDE) Interview Process – My Experience (comment by u/speedy_string)PublisherReddit r/OfferEngineeringSource typecandidate report on Reddit

AI rules by company

Whether you may use an AI assistant changes by company and by stage, and guessing wrong can cost you a round you were ready for.

Two warnings. First, a rule for one stage says nothing about the next: Anthropic encourages Claude for interview preparation and asks for no AI in take-homes unless it says otherwise. ^[42]Source 42Guidance on Candidates' AI UsagePublisherAnthropicSource typecompany website Second, Palantir’s Build to Apply rule covers the project for one Deployment Strategist track, not the interviews after it, and we found no first-party Palantir rule on AI in live FDSE interviews.

Where nothing is published, send this after the recruiter screen:

“Before my technical rounds, could you tell me, for each stage, whether AI coding assistants are allowed, and which tools? Is there a page with your policy I can read?”

In Pro, our lesson on AI rules by company and stage has the full table and the stage-by-stage version.

What no one publishes

Three things you will see quoted everywhere have no source behind them.

• No published pass rates. No FDE employer publishes a pass rate for any round. The earliest version we found is a table on a prep site, dated May 2026, that attributes its figures only to unnamed candidates and shows no data behind them. ^[44]Source 44Forward Deployed Engineer Preparation Guide: Complete Interview & Career Path Roadmap 2026Publisherexplainx.aiSource typeinterview prep site Later posts repeat the figures, some citing other prep sites, and the guide one of them cites does not contain them. ^{[45, 46, 47, 48]}Source 45Forward Deployed Engineer Interview Questions: A 2026 Prep GuidePublisherPerspective AISource typeinterview prep siteSource 46Forward Deployed Engineer interview questions (2026): every round, with real examplesPublisherDEV CommunitySource typeinterview prep siteSource 47Cracking the Forward Deployed AI Engineer InterviewPublisherAI Engineering Insider (Substack)Source typeinterview prep siteSource 48Forward Deployed Engineer Interview: The Definitive 2026 Guide (FDE)PublisherAced (formerly Exponent)Source typeinterview prep site
• No published round weights. No employer publishes how much any round counts. The weights that circulate appear in the same table, with the same lack of data.
• No published timelines. No employer publishes an end-to-end FDE timeline. Some company-wide hiring pages give a range that covers every role they hire, not FDE in particular. ^{[29, 36]}Source 29Our hiring process / Interview prepPublisherDatabricks CareersSource typecompany hiring pageSource 36Our hiring process - Google CareersPublisherGoogleSource typecompany hiring page A single candidate’s timeline is one data point.

What to do instead: prepare every round in your loop as if it were the one that decides, and ask your recruiter what the next stage covers. The question costs you nothing.

Our post on what no one publishes traces each figure to its origin, and the decomposition guide covers the pass rate that circulates in detail.

Pick a prep plan

How you prepare depends on how long you have. Whatever the distance, start the same way: measure yourself on both sides of the double bar in the same week, one technical problem without AI and one customer problem out loud. Expect one side to be weaker than you assumed, and give it more of your time.

• Your onsite is within a week. Measure both sides on the first day, then split the days between timed customer cases, coding, a deep dive on your own project and spoken stories. Your FDE onsite is next week lays out the days.
• You have two weeks. On the first day, write the token bucket cold and run the free case. Then take one round a day from your recruiter’s list, with its questions from this guide, and write deep dives on your own projects in the evenings. Run a full mock loop on the second-to-last day, and keep the last day light.
• You have a month. Suits a first FDE loop: every round at working depth, one practice take-home, and a full mock loop in the last week. How to run an FDE mock interview on your own shows how.
• You have two months, or no date yet. About an hour on weekdays and a longer block at the weekend. Work through every round in this guide, starting with the ones for your kind of company, and run two mock loops a few weeks apart so you can see what changed.

For the customer side, the practice case is free. For the technical side, start with the token bucket and a messy CSV export. Pro adds the Pro lessons and the model answers, and it starts with a 7-day free trial. The pricing page has the details.

Common mistakes

These come from the pitfalls we list on our question pages, each with its fix.

1. “We” for every decision. The interviewer cannot find anything to credit to you. Fix: before the round, write down the decisions that were yours, and say “I” for those.
2. Explaining the cause before the new date. In a slip conversation, two minutes of context reads as excuse-making. Fix: first sentence is the new date and plan.
3. Designing before asking. A generic RAG or microservices diagram with no trust boundary or permission check. Fix: ask who uses it, what data it may touch, and what happens when it is wrong.
4. A clever feature and no metric. In decomposition, it is easy to chase something interesting and never say how you’d know it worked. Fix: commit to one metric in the first five minutes.
5. Tools instead of evidence. Asked “how do you know it works?”, they list dashboards. Fix: name the golden set, the metric and the decision it supports.
6. A “why FDE” that is really “why sales engineering”. Talking about demos and workshops invites “so why not apply for that?”. Fix: name the building you want to do.
7. Refilling on a timer. In the rate-limiter problem, a background timer per user. Fix: compute the refill from elapsed time on each call.
8. Summing before checking the grain. A join to a child table multiplies rows, and the total comes out too high. Fix: say the grain of every table before you aggregate.

Our post on common FDE interview mistakes goes through each round in turn.

Every post in this guide, by the question you have

This guide is the map. Each post below takes one question from it and answers it in depth, with examples and the words to use.

Company loops

Start with what your company publishes and what candidates describe. A company guide keeps the two apart, with each report dated: Palantir, OpenAI, Google and Databricks, and every company guide in one place.

• Palantir FDSE interview experiences: published steps beside dated candidate reports
• The re-engineering interview: fix someone else’s code, then extend it
• The learning interview: learn a concept on the spot, out loud
• The Palantir FDSE internship interview: the early-talent steps and what interns report
• Palantir Build to Apply: how to build and film the demo
• The OpenAI FDE take-home: what OpenAI says and what candidates report
• Why Anthropic?: the motivation answer without reciting the mission page
• The Google FDE loop: the RRK round and the agentic design role-play
• Stuck in Google FDE team matching: what happens after the loop
• Sierra’s AI-native interview: Plan, Build and Review, walked through
• Cognition’s deployed engineer take-home: what candidates built with the Devin API
• C3 AI’s AI screening interview: the AI screen and the coding rounds after it
• The Salesforce Agentforce FDE interview: what candidates report, round by round
• The Databricks AI FDE coding round: applied data science and machine learning

If your company is not listed, read its postings line by line with how to read an FDE job posting, which is free, and ask the recruiter the questions no page answers.

The conversation rounds

• The FDE recruiter screen: every question, with how to answer
• Tell me about yourself: a one-minute answer that sets up the rest
• The FDE hiring manager interview: what they probe, and why
• The project deep dive: presenting your work when they keep asking why
• STAR for FDE behavioral questions: the format adapted to customer stories
• The ownership audit: fixing the “we” problem before the round
• A customer escalation you owned: a structure and a worked answer

Coding and SQL

• Do FDE interviews have LeetCode?: company by company
• A token bucket rate limiter: the code and the follow-ups
• The API integration round: retries, pagination and idempotency
• A messy CSV: parse it, and report what you dropped
• FDE online assessments: HackerRank, CodeSignal and AI-run screens
• AI-assisted coding interviews: using the assistant so they see your judgment
• SQL window functions: the patterns that come up
• Join fan-out: why your revenue is too high

Design, AI systems and evaluation

• Enterprise system design is not “design a feed”: a full walkthrough
• The RAG system design interview: retrieval inside a customer’s constraints
• The agentic system design interview: tools, permissions and guardrails
• Prompt injection defense: what to say when they ask
• Fine-tuning vs RAG vs prompting: choosing, and saying why
• A customer says requests are failing: the first hour, step by step
• How do you know your AI system works?: the direct answer
• LLM-as-a-judge pitfalls: failure modes to raise first
• Building a golden set: for a customer with no labeled data
• Prompt-engineering tests: when a timed prompt test is in the loop

Customer rounds

• The customer role-play interview: when the interviewer plays your client
• Telling a customer the project is late: the new date first
• Scope creep in the client round: holding scope without losing the room
• Explaining AI mistakes to an executive: plain words for a hard question
• Discovery call questions for engineers: what to ask in the first meeting

Take-homes and AI rules

• Forward deployed engineer take-homes: what real prompts ask for and how to scope
• The take-home walkthrough video: a script to record from
• Voice AI agent take-homes: when yours involves a voice agent
• Can you use ChatGPT or Claude on a take-home?: the published rules and how to disclose
• Which companies allow AI tools in interviews: the rules, stage by stage

Preparation and reading the evidence

• Your FDE onsite is next week: how to spend the days you have
• How to run an FDE mock interview on your own: round by round
• Questions to ask at the end: find out what the job really is
• Common FDE interview mistakes: what went wrong and the fix
• Rejected as “not technical enough”: what it means and what to do next
• FDE interview reports on Reddit and Blind: how to read them
• What no one publishes: pass rates, round weights and timelines

Start with the customer side

The one thing that tells you most about your readiness is a real customer problem, run out loud against the clock. The free practice case gives you a vague customer problem, an AI customer who answers what you ask, and a 10-minute clock, then a score that quotes what you said. Start the free practice case: sign in with Google and you’re in.

When you want more than the free material, here is what Pro adds to the links above. Every question linked in this guide shows its framework free, and some show their model answer free too. Pro opens the model answers across all 180 questions, all 3 practice cases at every length, and every Pro lesson as it is published, and it starts with a 7-day free trial. See what Pro includes.

Questions people ask

How long does the FDE interview process take?

No employer publishes an end-to-end timeline for its FDE loop. Some company-wide hiring pages give a range that covers every role they hire, not FDE in particular, so it does not tell you what your loop will take. Ask your recruiter for the schedule of every stage right after the first call, and plan your preparation around the dates they give you.^{[29, 36]}Source 29Our hiring process / Interview prepPublisherDatabricks CareersSource typecompany hiring pageSource 36Our hiring process - Google CareersPublisherGoogleSource typecompany hiring page

Is the FDE interview harder than a software engineer interview?

It is different rather than easier. At least one employer says FDE candidates must pass its software engineering loop, and FDE loops can add customer-shaped rounds, such as an open-ended customer problem or a round where the interviewer plays a customer. Prepare for both bars, not one.^[2]Source 2What is a Forward Deployed Engineer? (FDE Explained) feat. Leo Mehr of Ramp (YouTube auto-generated English captions)PublisherdearCC (Clara Shih), YouTubeSource typerecorded talk or interview

Can I use AI tools in an FDE interview?

It depends on the company and the stage. Google says AI tools are not permitted during its interviews. Anthropic says no AI in live interviews or take-homes unless it says otherwise. Sierra’s engineering onsite includes a build with the AI tools of your choice. Where nothing is published, ask your recruiter in writing before the first technical round.^{[23, 36, 42]}Source 23The AI-native interviewPublisherSierraSource typecompany blogSource 36Our hiring process - Google CareersPublisherGoogleSource typecompany hiring pageSource 42Guidance on Candidates' AI UsagePublisherAnthropicSource typecompany website

Do FDE interviews have LeetCode questions?

Some loops test algorithms and some test practical work, so prepare for both. Palantir’s coding guide says a core facet of a good coding interview is turning an algorithmic idea into working code, and that it will not ask about obscure features of a language. Ramp’s blog lists data structures among the things its FDE hiring checks, next to debugging and system design. Practice one classic algorithm problem and one practical build, such as a rate limiter or a messy file.^{[1, 9]}Source 1Forward Deployed EngineeringPublisherRamp Builders (engineering blog)Source typecompany blogSource 9Writing Good CodePublisherPalantirSource typecompany hiring page

What is the decomposition round in an FDE interview?

It is an open-ended round where you get a vague customer problem and break it into something you could build. Palantir’s own guidance for open-ended questions is to lay out the alternatives and trade-offs, reach a concrete approach, and deliver a functioning idea first, then expand it.^[17]Source 17Palantir Careers | Navigating Open-Ended QuestionsPublisherPalantir TechnologiesSource typecompany hiring page

How many rounds are in an FDE interview?

It varies by company. Palantir’s early-talent timeline lists six steps, from a HackerRank coding challenge to the offer. Databricks’ general careers page describes a recruiter call, a pre-onsite screen, an onsite loop of typically four to six interviews, and a presentation for some roles. Ask your recruiter for the list of rounds and prepare for each one by name.^{[7, 29]}Source 7Students | Palantir Careers (timeline image: RecruitingTimeline_V3.jpg)PublisherPalantirSource typecompany hiring pageSource 29Our hiring process / Interview prepPublisherDatabricks CareersSource typecompany hiring page

How should I prepare for an FDE interview?

Read what your target company publishes about its process and AI rules, list the rounds your recruiter names, and practice each one out loud against a clock. Measure yourself on both sides of the role early, one technical problem and one customer problem, and spend most of your time on the weaker side.

What do forward deployed engineers get paid?

Posted pay depends on company, level and location, and a posting’s band may not say whether it is base or total pay. Our salary guide collects the bands employers post and the H-1B filings, each dated, and says what each figure does and does not measure.

Keep reading

Guides

• The decomposition interview: how to break down a vague customer problem
• What is a forward deployed engineer?
• Forward deployed engineer salary: what employers post and file

Lessons

• The evidence map: what employers publish, what candidates report, how to read both
• What FDE coding rounds test, by the evidence
• What customer rounds look like, and the core moves

Questions

• Why forward deployed engineering, and not a software engineering role?
• Pick one project from your résumé and take me through it in depth: the problem, your design, what broke and what you would change.
• A customer asks how you know your AI system works. Answer them.