An API deprecation announcement checklist has one job: let an affected team decide whether it must act, what it must change and which date controls the risk. “We are modernising our API” does not do that. Name the retired surface, the supported replacement, the lifecycle dates and the evidence a developer can check.

Sources checked: 26 October 2026. Vendor lifecycle commitments differ by product, release stage and contract. The Google Cloud and Stripe documents below are examples of how providers publish those rules, not a universal policy for every API.

Separate the four dates

A useful announcement distinguishes at least four moments:

  1. Announcement date: when the notice becomes public.
  2. Deprecation date: when the old interface is discouraged and may stop receiving improvements.
  3. End of support: when the provider stops promising support, fixes or compatibility.
  4. Removal or shutdown: when calls are rejected or the interface disappears.

Do not collapse them into “sunset” unless the announcement defines exactly what that word means. Give dates in an unambiguous format and include a time zone for a time-specific shutdown. If the provider has only approved a month or quarter, say that; do not invent a day for a cleaner headline.

A lifecycle policy can set a minimum notice period, but that period may not cover every offering. Google Cloud’s deprecation policy says its terms depend on the applicable agreement and excludes pre-general-availability offerings from that policy. Before an announcement quotes a general promise, check the exact product, release stage and customer agreement.

Identify the affected surface precisely

Write the affected API the way a developer sees it:

  • product and service name;
  • API version or dated version;
  • endpoint, method, field or event type;
  • SDK package and minimum replacement version;
  • region, account type or feature flag, if relevant;
  • whether existing integrations, new integrations or both are affected.

“Legacy API” is not enough if three versions remain in production. Link the canonical API reference, changelog or release note beside the name. A screenshot of a dashboard can illustrate the change, but it should not replace a stable, linkable description.

Stripe’s versioning documentation shows why the distinction matters. An account can have an API version; an SDK release can align with a particular API version; and webhook events can use the version set on the endpoint or the account default, depending on how the endpoint was created. A migration notice should tell teams which of those surfaces they need to inspect.

State what happens after each deadline

Readers need the observable consequence, not an adjective.

For each date, say whether the old API will:

  • continue working without new features;
  • receive security or critical fixes only;
  • reject new account enrolment;
  • return a warning or response header;
  • stop accepting requests;
  • return a named error;
  • preserve read access while write calls stop;
  • remain available under a paid or contracted exception.

If the exact shutdown behaviour has not been approved, write “to be confirmed” in the internal source pack and do not publish a guessed error code. The announcement can still tell readers what is known and when the missing detail will be added.

Name the supported replacement

A migration target needs more than a product name. Link the replacement reference and list the differences that change implementation work:

  • authentication or permission changes;
  • renamed or removed fields;
  • new pagination, rate-limit or idempotency behaviour;
  • changed response types and error handling;
  • webhook event or signature changes;
  • SDK version requirements;
  • data backfill or reconciliation needs.

Stripe advises teams to test a new API version before committing an account upgrade and to review the changelog and SDK version. That is a useful pattern for any provider: link the compatibility record and describe the test path. Do not claim that a replacement is drop-in unless the engineering owner has demonstrated that result.

Publish a migration sequence

Give readers an ordered route they can adapt:

  1. Inventory calls, fields, SDKs and webhook endpoints that use the retiring surface.
  2. Read the replacement reference and the version-specific changelog.
  3. Create a test or sandbox integration.
  4. Run success, failure and retry cases with representative payloads.
  5. Compare outputs and reconcile stored data.
  6. Update monitoring, alerts and operational runbooks.
  7. Deploy to a controlled portion of traffic.
  8. Confirm rollback conditions and owner.
  9. Complete production migration before the support deadline.
  10. Remove old credentials and code only after verification.

This is a checklist, not a claim that every migration is safe in ten steps. If the change handles payments, identity or regulated data, name the specialised review the team needs.

Include test and rollback evidence

A migration announcement becomes more credible when it links to evidence a developer can run:

  • a versioned quickstart;
  • sample requests and responses;
  • a test environment or sandbox;
  • migration and rollback instructions;
  • a compatibility table;
  • known limitations;
  • a status or incident page;
  • a channel for technical support.

For a scheduled breaking change, state whether teams can pin the old version temporarily, and under what conditions. If the platform does not offer a rollback, say so plainly. Avoid “seamless” and “no action required” unless the provider has defined the affected group and verified both claims.

The press release source pack explains how to keep approved claims, supporting documents and owners together before distribution.

Treat webhooks as a separate migration surface

An API client and a webhook endpoint can follow different version rules. A team may upgrade outbound requests while still receiving older event payloads, or the reverse.

The announcement should therefore answer:

  • Which version generates each webhook payload?
  • Does upgrading the account change existing endpoints?
  • Must the endpoint be recreated or explicitly upgraded?
  • Are event names, signatures or retry rules changing?
  • Can old and new payloads be tested side by side?

Stripe’s documentation says webhook version behaviour depends on endpoint creation and account-version settings. The practical lesson is broader: never use “API upgraded” as proof that every inbound event path changed too.

Write the headline and opening around impact

A useful headline names the surface and the action:

Orders API v1 will stop accepting write requests on 30 April 2027

The opening should answer, in one paragraph:

We will deprecate Orders API v1 on 15 January 2027 and stop accepting its write requests at 17:00 UTC on 30 April 2027. Integrations that create or update orders must migrate to Orders API v2. Read-only v1 requests are not covered by this notice. The migration guide, version comparison and test endpoint are linked below.

Those details are illustrative. Replace them with approved facts; do not borrow the sample dates or behaviour.

Keep one canonical notice

Publish one maintained page that holds the current scope, dates, replacement links and update history. Other channels should point to it.

A changelog entry, email, dashboard banner and social post can have different lengths, but they should not introduce a different shutdown date. Record corrections on the canonical notice rather than silently replacing the text. If dates change, say what changed, when and why.

For a downloadable technical note, check that the HTML and file remain aligned using the HTML press release and PDF checklist.

Final publication check

Before release, confirm:

  • product and version names match the docs;
  • dates and time zones match the approved lifecycle record;
  • release-stage and contract qualifiers are present;
  • affected and unaffected users are distinguishable;
  • the replacement is currently available to the stated users;
  • SDK and webhook implications are explicit;
  • migration, test and rollback links open;
  • support ownership and escalation route are current;
  • every distribution variant points to the canonical notice;
  • the public page and downloads show the same facts.

Open the published URLs, not only the CMS preview. A correct source document can still become a broken link, cropped table or stale downloadable file during handoff.