CrackingWalnuts
Checked 3 August 2026. Anthropic describes the tools used and the interview style but publishes no round count, duration or timeline. Everything structural here is commonly reported by candidates. Source: anthropic.com/careers.
| Round | Duration | What it tests |
|---|---|---|
| Phone Screen | 60 min | Strategy conversation. |
| System Design Strategy | 90 min | Multi-year AI strategy at company scale. |
| AI Architecture Review | 60 min | Deep critique of an Anthropic-scale architecture. |
| Cross-Org Influence | 60 min | How you align research, engineering, and product. |
| Technical Vision (Writing) | Take-home | Strategy memo for an Anthropic-scale problem. |
| Hiring and Mentorship | 60 min | Staff hiring stories. |
| Behavioral (Principal Scale) | 60 min | Company-level impact with safety framing. |
| Senior Leader Round | 60 min | Vision, leadership style, fit. |
IC6 is the principal-level IC role. The bar is "sets AI strategy at company scale with safety mission framing, hires and grows IC5s, influences company-level direction across multiple years". You are expected to have a real technical point of view on where the company should go, and to defend it.
At principal scale the safety mission is the frame, not a constraint you account for. Anthropic expects you to reason about misuse, prompt injection, hallucination failure modes, and auditability as first-order concerns in any architecture or strategy.
Targeted guidance per round in this loop. Each section links to the matching track on the site. There is no shortcut list, the bar moves loop to loop, so build the pattern recognition and the stories from real practice.
Work the pattern templates until the recognition is instant. Trace one mock problem per pattern. Practice stating time and space complexity out loud before you write code.
Anthropic IC6 (Principal Engineer) has one design round: AI Architecture Review (60 min): Deep critique of an Anthropic-scale architecture.. Bar is multi-year architectural bets and cross-org technical strategy. You should be naming specific decisions you would defend in a roomful of senior engineers. Pick problems from the track at the scale this loop tests and rehearse the structure: requirements, numbers, high-level design, data model, API, deep dive on one part, trade-offs.
Principal bar. Multi-year bets, executive-level communication, cross-org influence, and growing Staff engineers. The behavioral rounds often outweigh technical-depth rounds in the final hiring decision at this level. Frame stories around safety-mindedness, mission alignment, and judgment under uncertainty about capabilities.
Write a real strategy memo for a problem you understand. Edit it twice. Read your own writing back the next morning. Aim for clear prose, specific recommendations, named trade-offs.