Interview Experiences

Real candidates, real loops: every round, what was asked, and how it ended.

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25 stories

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MercorSoftware Engineer
Oct 2026

No-Coding Technical Screen with Code-Reading Questions, Did Not Pass

I applied online. There is no recruiter screen - first call is a HM screen where they ask you basic questions. Next screen is a 30 minute technical screen with no coding. Mine had 4 questions - Tell me the worst sorting algorithm - (n!) and explain how you would calculate each permutation You visit two coffeeshops A and B and order 2 drinks from each. Each drink gets a quality score. What is the…

RejectedTechnical Screen1
MercorSoftware Engineer
Oct 2026

Technical Screen with Bloom Filter and Payment Idempotency Debugging

Almost all of these were questions I had already seen in interview experience posts! Worst sorting algorithm: I talked about enumerating every permutation and checking whether each one is sorted. Coffee shop: A and B each buy two cups of coffee. What is the probability that A's two cups taste better than B's two cups? There are 1M user_ids. How do you efficiently check whether an id exists, and a…

Technical Screen0
MercorMachine Learning Engineer
Sep 2026

Three Onsite Rounds, Kicked Out of the Meeting Room Mid-Interview

I finished interviewing at this company yesterday. My background is physics AI. I did competitive programming back in high school, and I figured I could cram a system design book for a few days and pass this onsite. Turns out I was still too green. The questions were pretty standard; it's on me for being too weak and wasting the opportunity. The interview was chaotic: in the middle of it, people…

Onsite0
MercorSoftware Engineer
Sep 2026

30-Minute Rapid-Fire Technical Screen, Rejected After Three Questions

The first round at Mercor was a 30-minute live technical interview. It was rapid-fire Q&A, where you try to answer as many questions as possible. I only got through 3 questions, so I didn't pass. The first question was to explain in detail a sorting algorithm faster than O(n^2). I gave merge sort. The second question was to give one slower than O(n^2). For brute force you can shuffle and then com…

RejectedTechnical Screen0
MercorMachine Learning Engineer
Sep 2026

Probability Phone Screen on PII Detection

I'm sharing my Mercor MLE phone screen, the probability round. I don't think anyone has posted this one here yet. Good luck to everyone landing offers soon. Part 1 We anonymize customer datasets by replacing every real name with a fake one. The first step is finding them: a detector goes through a document token by token, flagging whatever looks like PII. Take a document with 100 PII tokens and 1…

Technical Screen0
MercorSoftware Engineer
Sep 2026

Applied AI Tech Screen with an Async Refund Debugging Question and Rapid-Fire LLM Questions

Today I had a tech screen for Mercor's Applied AI role. The debugging question: The other rapid-fire questions: What is idempotency, and why do we need idempotent operations? What is RAG, and how is it related to fine-tuning? How would you handle context limit exceeded in an LLM application? LLM calls are usually stateless. How would you make an LLM application stateful? How would you handle prom…

Technical Screen0
MercorSoftware Engineer
Sep 2026

A Rushed 30-Minute Screen on Sorting, Probability, and a Cache Race Condition

The interviewer was a principal from Caltech. He talked fast and used a lot of technical jargon, like a college professor would. It was rushed, only 30 minutes. Explain a sorting algorithm better than O(N^2). Merge sort — recursively split the array into left and right halves until there are only 2 elements left, then merge by inserting the smaller of the two into a new array and returning it (N…

Technical Screen0
MercorSoftware Engineer
Aug 2026

25-Minute Screen, Sorting Complexity and Cache Review, Rejected

Sorting Complexity They asked me to come up with a sorting algorithm that is as inefficient as possible and explain its time complexity. One idea is to enumerate all permutations of n distinct elements and check one by one whether each is sorted. There are n! permutations in total and each check takes O(n), so the worst-case time complexity can reach O(n × n!). Strictly speaking there is no singl…

RejectedTechnical Screen0
MercorSoftware Engineer
Reported Jul 2026

Mercor Software Engineer interview with resume-tailored AI questions

I went through an interview flow that was entirely AI-based, and I found it surprisingly efficient. The AI generated questions tailored to my resume and the job description, and the experience felt almost human, more like a real conversation than a cold checklist. The questions covered system design prompts and coding and code-practice topics, and I usually had enough time to think through my ans…

OfferOther0
MercorSoftware Engineer
Reported Jul 2026

Mercor Software Engineer interview with a three-section HackerRank assessment

After I applied, the first step was an online HackerRank-style assessment with three sections. It covered data and algorithms, data pipelines, and SQL-style questions, so I had to move between very different problem types one after another. A short time later, I had a 30-minute conversation with the hiring manager. That discussion felt mostly behavioral, with some technical back-and-forth mixed i…

Online Assessment0
MercorSoftware Engineer
Reported Jul 2026

Mercor Software Engineer interview: five-minute interview with BFS and two-pointer questions

Scheduling went badly from the start. The first interview was canceled after I had already been set up for it, and the second lasted only about five minutes. During that short session, I received a Google Doc with three data structure and algorithm questions, including BFS and a two pointer approach. I needed a couple of minutes to get oriented, but the interviewer canceled before I could write a…

0
MercorSoftware Engineer
Reported Jul 2026

Mercor Software Engineer interview: AI-generated resume-tailored questions

My interview was conducted entirely through an AI platform. It generated questions tailored to my resume, and I found the process efficient and positive. Even though it used AI, it did not feel like a cold or mechanical interaction. The questions sounded natural, and the exchange felt more human than I expected. It was comprehensive for the time it took but still moved smoothly. I felt the AI pac…

Offer0
MercorSoftware Engineer
Reported Jul 2026

Mercor Software Engineer interview: a three-part HackerRank-style OA

After applying online, I received an online assessment on HackerRank-style tests with three sections. It covered data structures and algorithms, data pipelines, and SQL questions. Not long afterward, I had a 30-minute conversation with the hiring manager. It was mostly behavioral, with a few technical discussions mixed in. It felt like a standard early loop, with the OA setting the tone and the r…

Online Assessment0
MercorSoftware Engineer
Reported Jul 2026

Mercor Software Engineer interview canceled before three algorithm prompts could be answered

The process was chaotic from the start. My first interview was canceled, and when I finally got a second one, it ended extremely quickly, in around five minutes. Before it started, I was given a Google document with three data-structures and algorithms prompts, including BFS and two pointers. I tried to take a couple of minutes to get oriented, but the interviewer canceled before I could write an…

0
MercorSoftware Engineer
Reported Jun 2026

Mercor Software Engineer interview with concurrency and Redis

My interview was brief, around 30 minutes. The interviewer gave me some code and asked me to make it more robust. He nudged me toward concurrency and distributed-systems thinking, including how to process CSV data and coordinate synchronization with Redis. I felt behind because I was still early in graduate school and didn't have deep experience with that specific concurrency and distributed-syst…

0
MercorSoftware Engineer
Reported Jun 2026

Mercor Software Engineer interview: fast sorting questions and code review

One interview felt unusually fast and almost dismissive. I spoke with an engineer who asked quick, random questions, including the slowest sorting algorithm and its time complexity. I then did a quick code review of two functions. The whole decision seemed to happen within about five minutes, and the engineer appeared eager to wrap up after roughly ten. Another round was also very straightforward…

Technical Screen0
MercorSoftware Engineer
May 2026

Half-Hour Online Round of Code Review and Design Questions

Writing up an earlier Mercor fullstack round. It was online, about half an hour, and after I passed I got an onsite. It was mostly reading code to find problems and talking about design. I'm putting this together from my notes, so the order may not match what actually happened. Payment API Code that first calls an external provider to charge the customer, then writes a record to our own database.…

In progressTechnical Screen0
MercorMachine Learning Engineer
May 2026

A Gaslighting AI Interview and a Dead Reply Email

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WithdrewTechnical ScreenXP0
MercorApplied AI Engineer
May 2026

Referral Network Coding and a Live Search System Build

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RejectedOnsiteXP1
MercorSoftware Engineer
May 2026

A Product-Focused Recruiter Screen, Then Sorting Theory and a Concurrency Code Review

Round 1 — Background / recruiting round Self-introduction, plus walk through a project you've worked on recently. They dug deep into the project, but the follow-ups were all from a product angle rather than implementation details: was this decision made by your system or upstream? How do you define "it worked"? What's the success metric for this project? What's your understanding of what Mercor d…

Technical Screen0

What are interview experiences?

An interview experience is a candidate's own account of a hiring loop — not a question bank entry. It tells you the shape of the process: how many rounds there were, what each round actually tested, how long the gaps between them ran, and what the recruiter said at the end. That context is the part a question list cannot give you.

How to read them

Weight recent write-ups more heavily — interview loops change, often within a year. Read several for the same company and role rather than one: a single account tells you what one interviewer asked, while five tell you what the bar is. Note the outcome badge too, since a rejection write-up usually explains the gap far more precisely than an offer one.

Share your own

Every published experience earns 50 XP, and each of the first 3 likes it receives in a day earns you 10 XP more. Likes must come from established accounts; like-for-like swaps and likes from your own second account are not paid. Write it while the details are fresh — the round order, the exact prompts, and how much time you were given are what the next reader needs.

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