Which APIs answer without an API key?

Operations that answered an anonymous request with a machine-readable body on 2026-09-10. Every one was re-fetched and its body read, because an HTTP 200 is not by itself the API answering: an HTML documentation page and an OAuth consent screen both returned one.

55 records across 25 subjects, observed 2026-09-10. Every one carries a check you can run in a single request.

TokenJay API services7
BBC iPlayer Business Layer5
Medium API5
Canada Holidays API3
Color Name API3
D&D 5e API3
NamSor API v23
APIs.guru2
Clever-Cloud API2
DocuSign REST API2
MailboxValidator Email Validation2
Numbers API2
Random Lovecraft2
Remote Settings PROD2
StackExchange2
ClickSend REST API v31
Clubhouse API1
DigitalOcean API1
Geocoder REST API1
Greip API1
IP2Location.io IP Geolocation API1
MineSkin API1
Platform API1
Redeal Analytics API1
eNanoMapper database1

All subjects ยท the whole registry, machine-readable

This is not a list of good APIs or bad ones. It is a list of observations, each dated and each disprovable in one request. Absence from it means an operation was not examined, not that it is fine.