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Anthropic interview notes, page 18 of 32

Mid-sized

Most of these Anthropic write-ups come from Software Engineers (277), then Machine Learning Engineers (31) and Product Managers (10). The most reported rounds are the technical phone screen (129), the system design round (86), the behavioral / leadership round (45) and the hiring manager screen (17).

319 interview notes · updated Sep 2026

Anthropic·Backend Engineer·Onsite - Coding / Algorithms

May 2026
Interviewed for a backend engineer role at Anthropic and got rejected after a coding round that went sideways almost immediately. The recruiter said it would test concurrency, I prepped accordingly, and then the interviewer gave me a web crawler problem and never let me get to the concurrent part.
  • Implement a web crawler, starting with a single-threaded version.
  • Before coding a web crawler, how do you clarify requirements and edge cases such as URL normalization, fragment handling, scheme filtering, and stopping conditions?
  • How do you handle it when the interviewer's language preference conflicts with your chosen language mid-interview?
  • Is it worth sending post-interview feedback or an appeal after a rejection where the interview conditions seemed misaligned with what was communicated beforehand?

“I came in expecting a concurrency question, recruiter literally told me that's what they'd assess.”

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Anthropic·Software Engineer·Technical Phone Screen

May 2026
Anthropic coding interview focused on building an in-memory key-value store from scratch. Pretty straightforward scope for this part, no TTL or snapshot stuff yet, just the core operations.
  • Design and implement an in-memory database that supports set(key, value), get(key), and delete(key) operations.

“Not as trivial as it sounds once you start thinking about edge cases.”

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Anthropic·Software Engineer·Onsite - Behavioral / Leadership

May 2026
Behavioral deep dive at Anthropic for a software engineering role. The whole thing was basically one long project walkthrough, so pick something meaty or you'll run out of things to say fast.
  • Walk me through a significant project you've worked on, including your specific role, how you navigated conflicts with teammates or leadership, the size of the team, how long it ran, and what the actual impact was.

“This is the kind of question where you think you're ready and then realize halfway through you picked a project that's too small to sustain 30 minutes of follow-up.”

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Anthropic·Software Engineer·Onsite - System Design / Architecture

May 2026
System design round at Anthropic for a software engineering role, centered entirely on building a duplicate file finder from scratch. Pretty deep dive, they wanted to talk through everything from OS primitives to complexity analysis.
  • Design a command-line tool that finds duplicate files in a directory tree. Walk through how you'd enumerate files, filter candidates, and confirm duplicates efficiently.
  • What are the memory and I/O trade-offs when handling very large files in this tool?
  • How would you handle symlinks and permission errors when recursively walking the directory tree?
  • Once you've identified groups of duplicate files, what options would you expose to the user for resolving them, and what are the risks of each?
  • What is the time and space complexity of your duplicate detection approach?

“I started with the naive approach (hash everything) and they immediately pushed back on memory.”

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Anthropic·Software Engineer·Hiring Manager Screen

May 2026
Interviewed for an EM role at Anthropic, got one question about mentoring that felt deceptively simple but left me second-guessing my answer the whole way home.
  • How do you mentor top talent on your team?

“I rambled a bit.”

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Anthropic·Software Engineer·Onsite - System Design / Architecture

May 2026
Anthropic system design round, one big question about building a web crawler from scratch. Took longer than expected to get into the concurrency stuff and I think I lost points there.
  • Design a web crawler that starts from a seed URL, fetches pages, discovers and enqueues new links, avoids revisiting URLs, stays within a configurable domain allow-list, and handles concurrency, rate limiting, robots.txt, redirects, and failures.

“I started with the visited set and queue pretty quickly, that part felt natural.”

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Anthropic·Software Engineer·Technical Phone Screen

Jun 2026
Coding interview at Anthropic for a software engineering role. The problem started straightforward enough but then got layered with two extensions back to back, which is where things got interesting.
  • Implement the core algorithmic solution to a programming problem, then extend it to handle a constraint involving consecutive N elements, and further optimize it using only suffix-based information.

“The base problem was fine, got through it without much trouble.”

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Anthropic·Software Engineer·Online Assessment (OA)

Jun 2026
Took an online assessment for a Software Engineer role at Anthropic. One coding problem on merging accounts, ran out of time, a couple edge cases blew up, and ended up with 800 out of 1000. Recruiter emailed me about two hours later.
  • Given a list of accounts where each account contains a name and a set of emails, merge accounts that share at least one email address.

“Did not finish.”

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Anthropic·Software Engineer·Technical Phone Screen

Jun 2026
Interviewed for a data analyst role at Anthropic and got hit with a product ROI modeling question that was more open-ended than I expected. Not a lot of structure given, just kind of thrown into it.
  • How would you build a model to estimate the expected return on investment for a new product launch?

“I fumbled the opening a bit because I started listing metrics before I even defined what ROI meant in this context.”

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Anthropic·Software Engineer·Technical Phone Screen

Jun 2026
Interviewed for a data analyst role at Anthropic, one round, pretty standard stuff but the dataset question tripped me up more than I expected.
  • Walk me through a project where you had to clean and organize a large, messy dataset.

“I had an example ready but rambled way too much about the cleaning steps and never really landed on what the business impact was.”

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