# Nelson Elhage

> Nelson Elhage is a systems engineer turned AI safety researcher who has left fingerprints across the modern software stack. At Anthropic, he co-authored foundational work on mechanistic interpretability and transformer circuits that shaped how the field understands language models. Before that, he was employee ~30 at Stripe and a founding engineer of Sorbet, the Ruby typechecker now used across one of the world's largest payment platforms. His open-source tools - reptyr, livegrep, and ministrace - are staples in the Linux hacker's toolkit. He blogs at 'Made of Bugs' and runs a Buttondown newsletter on computer systems.

- **Role:** Member of Technical Staff at Anthropic
- **Organizations:** Anthropic, Stripe, Ksplice, Oracle
- **Nationality:** American
- **Education:** Bachelor of Science, Computer Science (Course 6), Massachusetts Institute of Technology
- **Known for:** Co-authored 'A Mathematical Framework for Transformer Circuits' (2021) - a foundational paper in mechanistic interpretability, Co-discovered 'induction heads' - key circuits explaining in-context learning in transformers, Co-founded Sorbet, Stripe's open-source static Ruby typechecker, adopted across a major global payments platform

## Career timeline

- **2006-2008** — Taught computer science topics through MIT ESP (Educational Studies Program)
- **~2009** — Founded/worked on Ksplice, a technology for rebootless Linux kernel updates
- **2011** — Presented KVM vulnerability research at Black Hat USA 2011
- **2011** — Oracle acquired Ksplice; Nelson continued as Architect at Oracle
- **~2013** — Joined Stripe as approximately employee #30
- **2017-2018** — Co-founded Sorbet project at Stripe - static type checker for Ruby; presented at Strange Loop 2018
- **~2020** — Joined Anthropic as Member of Technical Staff
- **2021** — Co-authored 'A Mathematical Framework for Transformer Circuits'
- **2022** — Co-authored 'In-context Learning and Induction Heads'
- **2022** — Published 'Mechanistic Interpretability, Variables, and the Importance of Interpretable Bases'
- **2023-present** — Working on Anthropic's pretraining team

## Achievements

- Co-authored 'A Mathematical Framework for Transformer Circuits' (2021) - a foundational paper in mechanistic interpretability
- Co-discovered 'induction heads' - key circuits explaining in-context learning in transformers
- Co-founded Sorbet, Stripe's open-source static Ruby typechecker, adopted across a major global payments platform
- Created reptyr - a widely used Linux tool with 6,200+ GitHub stars for reparenting running processes to new terminals
- Built livegrep - real-time regex search for large codebases; powers Mozilla's SearchFox
- Early Ksplice engineer enabling rebootless Linux kernel security updates (later acquired by Oracle)
- GitHub achievements: Pull Shark x3, Starstruck x4, Mars 2020 Helicopter Mission contributor
- 953+ GitHub followers across 220 repositories
- Presented at Black Hat USA 2011 on KVM security vulnerabilities

## Latest updates

- **2026-03** — Published 'From error-handling to structured concurrency' on blog.nelhage.com
- **2025-10** — Published 'Solving regex crosswords with Z3'
- **2025-07** — Published 'The ITTAGE indirect branch predictor' deep-dive
- **2025-03** — Published 'Performance of the Python 3.14 tail-call interpreter'
- **2025-01** — Published 'Building personal software with Claude' on his newsletter

## Links

- Website: https://nelhage.com/
- LinkedIn: https://www.linkedin.com/in/nelhage/
- Twitter/X: https://twitter.com/nelhage
- GitHub: https://github.com/nelhage
- Instagram: https://www.instagram.com/hellhage/

---

Profile page: https://yespress.io/nelson-elhage
Published by YesPress — https://yespress.io
Last updated: 2026-04-21