Observed arrival · 2026-10-27
apifacts: a changelog for API reality
An open registry of verified facts about what APIs, SDKs, and command-line tools actually do, with tools for agents and developers to check it.
- For
- Developers debugging third-party API behavior
- Worth noticing
- The pytest plugin sends nothing until a test fails; offline MCP mode answers from a snapshot packaged in the wheel.
Field notes
Each fact is described as a YAML file containing an error signal, a claim, dimensions, and evidence. The project says scheduled HTTP probes establish facts, and that a probe in one environment does not refute a fact from another; it adds a dimension instead. The check response can also include an unknown reason when no registry entry matches. For privacy, the page says stored observations are normalized and exclude bodies, headers, query strings, and raw IPs.
Observed signals
Read the marks
Editorial observations of this landing page, not a rating.
One card from the complete issue