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Simon Willison says LLMs make the freedom to modify open source tools practical

Simon Willison argues that LLMs turn open source's freedom to modify a tool from a theoretical right into a practical one, since the time cost of reading unfamiliar code is what pushed most programmers to lean on others instead. Several times a day he prompts Claude to clone a GitHub repo and explain how one part of it works, and hands "check out and build X" to Codex or Claude Code as a zero-time task. The compile step that once ended the attempt is now cheap enough for a developer to start patching the tools they use daily. Willison is not habitually modifying his own software yet, but sees a path to it that did not exist a year ago.

Source: simonwillison.net

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Most people can't justify the time commitment needed to read and then modify the code for tools they use very often.

Simon Willison

Why this matters

  • → LLMs make code modification practical by eliminating reading time
  • → Compilation friction drops from barrier to ten-minute errand
  • → Users can now own and patch tools instead of waiting for maintainers
Modifying code gets practical