Anthropic Staff Software Engineer Interview Experience — A Surprise Extra Round, Then a Downlevel to Senior

Overall the problems weren't hard, but there was a lot of code to write.

The phone screen was one round of coding — they asked the file deduplication problem (Q2), done on Replit.

The onsite (VO) had 5 rounds total — it was originally supposed to be 4, but they added one more afterward:

1. Round 1, Coding: asked the web crawler question (Q1). The interviewer asked if I'd seen a similar problem before, and I honestly said yes — which foreshadowed the extra round that got tacked on later.
2. Round 2, Hiring manager: asked basic questions.
3. Round 3, Culture interview: asked about AI-safety-related questions.
4. Round 4, System design: another old question from the forum — designing a GPU inference API.

After the interview, feedback was positive, but the recruiter said they were adding one more round on short notice, because the VO coding round was "inconclusive" since I'd said I'd seen a similar problem before. So I ended up doing another round with a completely new question.

The new question was to implement a Python LRU cache. They give you an already-implemented LRU cache, but it doesn't handle Python's variable-length arguments and keyword arguments properly — you need to add that support yourself. The follow-up was how to make the LRU cache persistent. I spent a ton of time on serialization for this part, which meant my code never actually ran by the end. I'd originally planned to use pickle, but the interviewer said I didn't need pickle and could just hand-roll JSON serialization/deserialization directly 😭, so I never finished the follow-up. Looking back, I should have just stuck with pickle so I could focus on the core logic instead.

Overall it moved pretty fast — the problems weren't hard, but there were a lot of pitfalls to watch out for.

After finishing all four rounds of the VO, the recruiter started talking about the package. Anthropic's offer isn't negotiable, and if you don't count the paper money, it's way below FAANG — and it seems like they downgrade your level too. I interviewed at the staff level, but the recruiter said they could only offer the internal level equivalent to senior, not staff, explaining that their internal leveling is FAANG minus one.