Countly vs GitHub Contribution Chart Generator

Countly is an open-source product analytics platform you self-host (or run as their managed cloud), ingesting events over a REST Data API keyed by a per-app `app_key` rather than a private secret — a live unauthenticated POST to a running Countly server (try.count.ly/o) confirmed the endpoint only demands `app_key`, returning a `missing_api_key` JSON error otherwise. The Community Edition is free and self-hostable under an AGPLv3-derived license; Countly also sells a paid Enterprise Edition with SSO, extra data sources, and dedicated support.

This is a keyless JSON API (not an image-rendering service, despite the name) with a single route, `/api/v1/{username}`, that returns a GitHub user's daily/yearly contribution counts — confirmed by inspecting the project's own source tree, which contains only one API file (`src/pages/api/v1/[username].js`); the actual chart image is drawn client-side from that JSON by a separate canvas library. A live unauthenticated GET returned a 200 JSON payload with no `Access-Control-Allow-Origin` header at all, correcting cors from "yes" to "no" (the header only appears on Vercel's default 404 page, not on the real route). Free and open-source, self-hostable on Vercel.