Where do the bugs live in popular open source?

Hotspot heatmaps of well-known projects: complex files that keep changing, over the last 12 months. Updated every week. Click a project to explore its map.

facebook/reactJavaScript
Half of all changes land in 40% of the code
Hottestpackages/react-dom-bindings/src/client/ReactFiberConfigDOM.js94
569 commits · 91 authors · bus factor shared · 21% fixes
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vuejs/coreTypeScript
Half of all changes land in 35% of the code
Hottestpackages/runtime-core/src/renderer.ts100
236 commits · 98 authors · bus factor shared · 85% fixes
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sveltejs/svelteJavaScript
Half of all changes land in 34% of the code
Hottestpackages/svelte/src/internal/client/reactivity/batch.js91
549 commits · 112 authors · bus factor shared · 71% fixes
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vitejs/viteTypeScript
Half of all changes land in 45% of the code
Hottestpackages/vite/src/node/plugins/css.ts95
602 commits · 168 authors · bus factor shared · 51% fixes
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tailwindlabs/tailwindcssTypeScript
Half of all changes land in 36% of the code
Hottestpackages/tailwindcss/src/utilities.ts98
211 commits · 49 authors · bus factor 1 · 22% fixes
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expressjs/expressJavaScript
Half of all changes land in 32% of the code
Hottestlib/response.js100
21 commits · 20 authors · bus factor shared · 43% fixes
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django/djangoPython
Half of all changes land in 33% of the code
Hottestdjango/contrib/admin/options.py100
536 commits · 180 authors · bus factor shared · 75% fixes
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pallets/flaskPython
Half of all changes land in 37% of the code
Hottestsrc/flask/app.py100
27 commits · 3 authors · bus factor 1 · 30% fixes
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fastapi/fastapiPython
Half of all changes land in 38% of the code
Hottestfastapi/routing.py86
282 commits · 37 authors · bus factor 1 · 22% fixes
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rails/railsRuby
Half of all changes land in 64% of the code
Hottestactiverecord/lib/active_record/connection_adapters/postgresql_adapter.rb91
1,780 commits · 315 authors · bus factor shared · 20% fixes
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gin-gonic/ginGo
Half of all changes land in 46% of the code
Hottestcontext.go86
57 commits · 42 authors · bus factor shared · 37% fixes
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ollama/ollamaGo
Half of all changes land in 31% of the code
Hottestserver/routes.go97
970 commits · 65 authors · bus factor 3 · 16% fixes
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tokio-rs/tokioRust
Half of all changes land in 34% of the code
Hottesttokio/src/runtime/builder.rs99
369 commits · 159 authors · bus factor shared · 13% fixes
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astral-sh/uvRust
Half of all changes land in 39% of the code
Hottestcrates/uv/src/lib.rs88
1,604 commits · 137 authors · bus factor shared · 10% fixes
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