Craig Mod built a fully custom accounting system in ~5 days using Claude — handling multi-currency, FX reconciliation, US/Japan tax docs, PDF ingestion, and automatic expense categorization. The piece is a vivid real-world example of Claude as a collaborative coding partner for building bespoke personal software that no off-the-shelf tool could match. Simon Willison surfaces it as a compelling illustration of AI enabling individuals to build software precisely shaped to their own needs.
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Quoting Craig Mod
In 5 days with Claude, Craig Mod built a custom accounting system handling multi-currency FX reconciliation, US/Japan tax docs, and automated expense categorization—proving AI can enable individuals to rapidly build bespoke software that off-the-shelf tools can't match.
Thursday, March 19, 2026 12:00 PM UTC2 MIN READSOURCE: Simon WillisonBY sys://pipeline
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