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API Impact Tracker – Know which API clients you'll break before deploying
- PeterDS 9mo agoHi HN, I built this after breaking production APIs one too many times. The problem was always the same: remove or change an endpoint, deploy, and a few hours later customers email saying their integrations broke. API Impact Tracker answers one simple question before deploy: "Which real clients will break if I ship this?" It works by tracking which clients use which endpoints (via middleware), normalizing paths (e.g. /users/123 → /users/{id}), and comparing real usage with your OpenAPI spec. Example output: $ api-impact diff openapi.yaml BREAKING CHANGE DETECTED DELETE /users/{id} Clients affected: - acme-inc (used 2h ago) - foo-app (used yesterday) Design choices: - Runs locally (SQLite) – no data leaves your infrastructure - No SaaS, no phone-home - Open source (MIT) - CLI + GitHub Action - Takes ~5 minutes to set up on an existing Express API I'd love feedback, especially on: 1) API versioning and deprecations 2) GraphQL support 3) Other API-change pain points you've seen Thanks!
- mickle00 9mo agowhy not just version API for breaking changes?
- PeterDS 9mo agoGreat question. Versioning definitely helps, and most teams do version their APIs. The problem I kept running into is that versioning answers “where do we put breaking changes?” but not “who is still using this?”