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Simon Willison

Category: entity Last updated: 2026-04-03 Status: draft

Summary

Simon Willison is a British-American software engineer based in Half Moon Bay, California. He co-created the Django web framework (used by Instagram, Pinterest, and Spotify), coined the term "prompt injection," created the Datasette data-analysis tool, and has been one of the most visible practitioners writing publicly about the transition to AI-assisted and agentic software engineering. His blog at simonwillison.net is a primary reference for practitioners navigating the shift.

Details

Background

  • 25+ years of professional software engineering experience
  • Co-created Django in the mid-2000s; powers major platforms including Instagram, Pinterest, and Spotify
  • Author of 100+ open-source projects; runs simonw/tools (small HTML/JS tools) and simonw/research (coding-agent research projects) on GitHub
  • Day job: building open-source tools for data journalism (enabling journalists to tell stories with data)
  • Lives in Half Moon Bay, CA; describes pelicans as a favorite animal and created the "pelican riding a bicycle" SVG benchmark for LLM evaluation

AI Contributions

  • Coined the term prompt injection in 2022, predating ChatGPT
  • Coined the term agentic engineering as a more precise alternative to "vibe coding" for professional AI-assisted development
  • Created the pelican riding a bicycle SVG benchmark — a qualitative LLM quality benchmark that has shown unexplained correlation with overall model capability
  • Writing an in-progress book on agentic engineering patterns, published chapter-by-chapter on his blog
  • Uses Claude Code for web extensively; writes much of his code on his phone while walking

Tools & Stack (as of early 2026)

  • Primary coding: Claude Code for web (Anthropic's hosted version; also accessible from iPhone app)
  • Secondary: GPT 5.4 (competitive with Claude Opus 4.6; sometimes cheaper)
  • Research on phone; code review via GitHub PR workflow
  • Gemini for image generation (for personal/fun use only; does not publish AI-generated images)
  • Has stopped using Google Search directly; uses AI search integration for research queries

Working Style

  • Runs 4 coding agents in parallel; finds it mentally exhausting by 11am
  • ~95% of code he produces is now AI-written
  • Uses simonw/tools GitHub repo as a hoard of reusable small tools
  • Uses simonw/research GitHub repo for agent-driven research reports
  • Starts new projects with a thin template (single passing test + boilerplate) rather than verbose CLAUDE.md instructions
  • Uses red/green TDD as a key prompt shorthand for AI agents

Consulting

Offers "zero-deliverable consulting" — paid one-hour calls with no deliverables or reports. Clients found through intermediaries rather than direct outreach.

Key Claims & Data Points

  • As of early 2026, ~95% of Simon's code is AI-written — [source: wc8FBhQtdsA]
  • Co-created Django, powering Instagram, Pinterest, Spotify — [source: wc8FBhQtdsA]
  • Coined "prompt injection" in 2022 before ChatGPT — [source: wc8FBhQtdsA]

Open Questions

  • What is the name/URL of the intermediary/channel through which Simon accepts consulting inquiries?
  • When will the agentic engineering book chapters be complete?

Sources