Azure DevOps Health vs CircleCI

Despite its name, this is the Azure Resource Health control-plane API (part of Azure Resource Manager), which reports the real-time and historical availability status of individual Azure resources rather than anything DevOps-pipeline-specific. Every call goes through management.azure.com and is authenticated like any other ARM provider — a Microsoft Entra ID (Azure AD) OAuth2 bearer token in the Authorization header, not a plain API key. A live unauthenticated GET against its availabilityStatuses endpoint returned a structured JSON error with access-control-allow-origin: * rather than a raw connection failure, confirming the service and its CORS support are live.

CircleCI's REST API triggers and inspects pipelines, workflows, and jobs, and manages projects, contexts, and self-hosted runners. The stored v1-reference docs URL now 404s live — CircleCI has fully moved API documentation to v2, whose own v1 docs page carries a banner recommending migration to v2 endpoints — so the URL was corrected to the current v2 reference. Authentication is reconfirmed as a personal API token: an unauthenticated GET to api/v2/me returned 401, and that same response (plus its OPTIONS preflight) carried no access-control-allow-origin header at all despite a Vary: Origin header, resolving CORS to closed rather than open. CircleCI's pricing page offers a Free plan (30,000 monthly credits, more for open source) alongside paid Performance plans, making it freemium.