How do their APIs compare?

These two repos serve very different purposes, so their "APIs" aren't really comparable in a like-for-like sense — one is a web framework, the other is a CLI/tooling utility for LLM prompt evaluation and workflow install. Let me lay out what each actually exposes.

expressjs/express — HTTP framework API

Express exposes a chainable, middleware-oriented API centered on an app object and req/res extensions:

• Routing/app-level methods: app.get, app.all (which applies middleware/handlers to every HTTP method by iterating methods and delegating to route[method]) [lib/application.js:L493-L501], plus app.render for view rendering [lib/application.js:L505-L520].
• Response helpers: res.set/res.get for headers [lib/response.js:L681-L700], res.links() for building Link headers from an object map [lib/response.js:L97-L109], and res.clearCookie() which forces expiration via a past date and strips maxAge [lib/response.js:L710-L718].
• Utility layer (lib/utils.js, the most-depended-on file per the import graph with 7 importers): normalizeType/normalizeTypes for MIME coercion [lib/utils.js:L52-L69], setCharset for rewriting Content-Type charset params [lib/utils.js:L224-L237], and ETag generators (exports.etag, exports.wetag) [lib/utils.js:L31-L48].

This is a synchronous, convention-based API meant to be composed via app.use()/middleware chains — the design favors small, chainable functions returning this or the response object.

juliusbrussee/caveman — no comparable public HTTP/web API

Caveman isn't a web framework at all. From what's visible, it's a set of internal scripts/hooks:

• src/hooks/caveman-stats.js exposes plain calculation functions like priceForModel(model) (a private lookup against MODEL_OUTPUT_PRICE_PER_M) [src/hooks/caveman-stats.js:L41-L47] and deriveSavings({ byMode, model }), which computes estimated token/cost savings from a compression ratio table [src/hooks/caveman-stats.js:L241-L250].
• bin/install.js has filesystem-walking helpers like walkDir(root, depth) [bin/install.js:L324-L334] and jetbrainsPluginPresent(needle) for detecting IDE plugin installs [bin/install.js:L310-L322].
• There's also evals/snapshots/results.json, which is eval/benchmark data (prompts + model responses across "arms" like baseline/terse/compress), not an API surface at all.

Bottom line: Express's API is a public, well-documented, middleware/routing surface for building web servers — validated by RepoPilot's architecture grade of A (99/100) with 0 import cycles across 141 files. Caveman, based on the retrieved chunks, exposes internal utility/helper functions (stats derivation, install-time filesystem scanning) rather than a public request-handling API — there's no evidence in the data of routes, middleware, or an HTTP-facing surface comparable to Express's.

If you want a narrower comparison (e.g., just their CLI entry points, or just how each handles configuration), I can dig into that with a targeted search.

FOLLOW_UPS:

• What does caveman's install.js script actually do?
• How does Express's routing internals work (lib/router)?
• What is caveman-stats.js used for overall?