For anyone who has to retire an API version
Version SunsetCheck your API's version lifecycle - then retire a version without breaking anyone.
Paste your versions with their release, deprecation and sunset dates, one response from a deprecated version, and the changes you have queued. Your browser measures every notice window against the floor for your audience (12 months public, 24 for mobile apps and enterprises), counts the versions alive at once, catches a version that is both deprecated and the default, reads the Deprecation and Sunset headers, classifies each queued change as breaking or not, ranks the version scheme, and writes the headers for the next version to retire. Then the policy, and the sunset plan.
The API, and a short interview free
Versions, headers and queued changes free
v2 | 2021-09-01 | 2026-03-01 | - | 41 | default - write "default" in the last column for the version unversioned or new integrators get.
How versions end today free
The checks free
What the page flags
The versions
Queued changes, by the breaking-change definition
Area by area
The headers for the next retirement free
Response headers on the retiring version
The policy metered
Pricing as soon as the session is ready...
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Caveats
Caveats
The page's check of this reply
Saved APIs
How it works - and what is sourced
The checks are the skill's failure modes and floors: notice of at least 12 months for a fully public API and 24 when consumers ship mobile apps or are enterprises (partners get the contract's number, internal teams contract tests); at most 2 or 3 versions alive at once; no version both deprecated and the default; no unversioned fallback; a written clock; headers plus a channel that reaches humans; a decided enforcement; a governance layer for every breaking change; and breaking changes at most about twice a year.
Headers follow the RFCs: Deprecation (RFC 9745) is @ and Unix seconds, Sunset (RFC 8594) an HTTP-date, and Link rel="successor-version" (RFC 8288) names the replacement. Dates are calendar days in UTC. A published sunset date still ahead is kept, never moved; a version already deprecated keeps its deprecation date. The scheme follows the skill's ranking: URI by default, header when versions ship on a calendar, additive-only for reachable consumers, date-pinned for frequent breaking changes and integrators who cannot be made to move.