Simon Willison’s Weblog

GPT-3 token encoder and decoder. I built an Observable notebook with an interface to encode, decode and search through GPT-3 tokens, building on top of a notebook by EJ Fox and Ian Johnson.

Posted 27th April 2023 at 11:48 pm

Recent articles

OpenAI are quietly adopting skills, now available in ChatGPT and Codex CLI - 12th December 2025
GPT-5.2 - 11th December 2025
Useful patterns for building HTML tools - 10th December 2025

projects 510 ai 1732 observable 50 gpt-3 67 openai 374 llms 1496

Monthly briefing

Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.

Pay me to send you less!

Sponsor & subscribe