API Documentation and Developer Experience Questions

Documentation and developer experience for API consumers: reference docs for endpoints and fields, OpenAPI-driven and interactive documentation, quickstarts and runnable code samples, doc comments that feed generated reference, changelogs, deprecation notices and migration guides, error messages and error tables that explain themselves, developer portals, sandboxes and onboarding flows. Covers developer experience (DX) as a product concern: time to first successful call, DX and docs-effectiveness metrics and dashboards, diagnosing onboarding drop-off, developer feedback loops, experiments and developer research, documentation standards and CI checks across teams, prioritising DX investment, and reducing support load through better docs and self-service. Designing the API itself (versioning policy, auth, rate limits, webhooks, gateways, SDK engineering) is a separate subject.