Anthropic Interview Questions — Page 7

Anthropic·Software Engineer·Technical Phone Screen

May 2026

Coding round at Anthropic for a software engineer role. The main problem was a classic sliding window question but the follow-up went somewhere I wasn't fully prepared for.

Given a string, find the length of the longest substring with no repeated characters. What's the time complexity and how do you get to O(n)?
How does your solution change if the string contains Unicode characters, including emoji with zero-width joiner sequences? Should those count as one character or multiple?

“Went fine.”

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Anthropic·Software Engineer·Hiring Manager Screen

May 2026

Short behavioral question from what seemed like an Anthropic engineering interview, probing whether I'd actually dealt with deadlines or coached anyone on a past project.

In the project you described, did you have direct experience managing deadlines or mentoring other people on the team?

“Felt like a follow-up designed to poke holes in whatever I'd just said.”

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Anthropic·Product Manager·Hiring Manager Screen

May 2026

Interviewed for a PM role at Anthropic and got asked about the Gen AI skills landscape, which sounds straightforward but actually requires you to have a real point of view on where the space is heading.

What Gen AI skills do you think will be critical for product managers in the next year?

“I rambled a bit here.”

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Anthropic·Software Engineer·Technical Phone Screen

May 2026

Anthropic software engineer interview that leaned heavily on systems-level thinking. The two problems were related but the follow-ups pushed into territory I wasn't fully prepared for.

Given a list of log entries in the format 'id event timestamp' where events are START or END, compute the exclusive execution time for each function ID. Calls can be nested and logs are in chronological order.
Follow-up: if timestamps can be equal and some log entries might arrive slightly out of order, how would you adapt the solution to handle or buffer an online stream correctly?
Given a stream of categorical events (like ERROR, WARN, INFO), find the earliest index where the same category appears N times consecutively. Return the start index of that window, or -1 if it never happens. Analyze time and space complexity.

“Stack-based solution, pretty standard once you see the pattern.”

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Anthropic·Software Engineer·Onsite - System Design / Architecture

May 2026

System design round at Anthropic for a software engineer role, focused entirely on designing Instagram's backend. Pretty deep dive covering feed generation, scaling, and recommendations. The kind of interview where you realize halfway through how many moving parts there actually are.

Design the backend for a photo-sharing app like Instagram, including photo uploads, a home feed, and the follow graph.
How would you generate a user's home feed? Compare fan-out on write versus fan-out on read and explain which you'd pick for a read-heavy system.
A celebrity account has 50 million followers and posts something. How do you handle the write storm under fan-out on write?
How would you partition the feed store and user data across many nodes, and why use consistent hashing instead of a simple modulo approach?
Walk me through how you'd design a 'people you may want to follow' recommendation feature.
A user follows 5,000 accounts. How do you keep their feed load fast under fan-out on write, and what does fan-out on read cost them?
When a user unfollows someone, what happens to posts that were already pushed into their precomputed feed?
How would you evolve a strictly chronological feed into a ranked feed without rebuilding the whole pipeline?

“Big open-ended opener.”

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Anthropic·Software Engineer·Technical Phone Screen

May 2026

Interviewed for a software engineering role at Anthropic and got a file system grouping problem. Pretty standard coding round, nothing too wild, but the parsing step tripped me up more than I expected.

You're given a list of strings describing directory contents, where each string encodes a root path followed by filenames and their contents. Group all file paths that share identical content, returning only groups of two or more files.

“The problem looks clean on the surface but parsing that input format took me longer than I'd like to admit.”

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Anthropic·Software Engineer·Technical Phone Screen

May 2026

Anthropic software engineer interview with a systems-focused coding question about web crawling, plus a meaty follow-up on concurrency and rate limiting. The kind of problem that feels manageable until they start asking about distributed correctness.

Implement a web crawler: given a start URL and a function that returns links from a page, collect all URLs sharing the same hostname. Your solution should avoid revisiting pages, handle cycles and duplicates, and deal gracefully with malformed URLs. Walk through time and space complexity too.
How would you extend the crawler to run with multiple concurrent workers, making sure no URL gets fetched more than once and that you respect a per-host rate limit?

“I went with BFS and a visited set, which felt right.”

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Anthropic·Software Engineer·Technical Phone Screen

May 2026

Anthropic software engineering interview that revolved around a single image-processing coding problem. Started straightforward, then kept escalating into concurrency and performance territory, which is where things got interesting.

Build a Python utility using Pillow that takes a list of image file paths and an output directory, converts each image to grayscale, resizes it to a target dimension, and saves the result. Start with a naive working solution, then scale it up for large batches of large images.
How would you handle errors when processing individual images in a parallel pipeline, and how would you think about memory usage when dealing with many large image files at the same time?
How would you measure and compare the performance of the naive sequential version versus the parallel version of this utility?

“The first part was fine, grayscale and resize with Pillow is basically two lines.”

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Anthropic·Software Engineer·Onsite - Behavioral / Leadership

May 2026

Behavioral screen for a SWE role at Anthropic. Just the one question but it's the kind that can spiral if you're not careful.

Can you describe a time when you did something that conflicted with your own values?

“This one sat me down hard.”

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Anthropic·Software Engineer·Technical Phone Screen

May 2026

Anthropic SWE interview with a filesystem path resolution problem that looked manageable at first glance but has enough edge cases to chew through your whole session if you're not careful. Symlink cycle detection was the part that tripped me up.

Implement a Unix-style `cd` path resolver that handles absolute and relative paths, dot components, symbolic links, and cycle detection, returning the final canonical path or "CYCLE" if a link loop is encountered.

“The basic path normalization part (splitting on `/`, handling `.` and `..`) came together pretty fast.”

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