API Deprecation

Definition & scope

API deprecation is a controlled process that marks an API, or a part of it, as obsolete. The intention is to eventually remove it, but it remains operational during a transition period. This gives developers time to migrate to a new solution.

Key distinctions

– Deprecation vs. removal / sunsetting / retirement: Deprecation is a warning signal that the API still works, but no new features will be added. Removal, or “sunsetting,” is when the API is actually disabled or deleted.
– Scope of deprecation: Deprecation can target different levels, not just entire API versions. It can be for a whole API version (e.g., v1 moving to v2), a specific endpoint, or an individual parameter. Narrow deprecation is less disruptive, while broad deprecation requires more planning and support.

Backward compatibility / graceful degradation

During the deprecation period, the main goal is to maintain backward compatibility. This means that existing clients should not break immediately. The API should continue to work, even if it is not the ideal way to use it, rather than just stopping.

Deprecation metadata / annotations

Deprecation should be formally announced in the API’s documentation and headers:

– In OpenAPI / Swagger, operations or paths can be marked as deprecated = true.
– The use of HTTP headers like Deprecation or Sunset (as per RFC 8594) can be used to warn clients in responses.
– A Warning header can be used to include details about the removal timeline and links to migration guides.

Rationale / why deprecate

API deprecation is often a necessity. Here are the core reasons and trade-offs behind the decision to deprecate an API.

Primary drivers

– Security & risk mitigation: Older APIs can have security weaknesses, out-of-date authentication methods, or unpatched parts. Deprecating them allows you to move to more secure, modern ways of doing things.
– Technical debt reduction: Supporting multiple old API versions adds to ongoing maintenance costs and complexity. Deprecation helps keep the API clean and easier to maintain.
– Performance, scalability & efficiency: Newer APIs often use more efficient data models, caching, or transport protocols. Removing older versions frees up resources and simplifies optimisations.
– Feature evolution / innovation: New API versions may introduce features that are not compatible with the old design. Deprecating outdated endpoints encourages developers to use the new, better features.
– Business strategy & alignment: Changes in a company’s direction, rebranding, or mergers may make certain APIs obsolete. Deprecation aligns the technical side of the business with its new goals.
– Regulatory / compliance changes: New legal, privacy, or data handling regulations may mean that some APIs can no longer be used. Deprecation allows for a controlled transition to new APIs that meet these standards.

Considerations & trade-offs

– User impact / churn risk: Deprecation can annoy users and may cause them to stop using a service if migration is difficult. Poorly handled deprecation can also harm a company’s reputation.
– Hidden dependencies: Some clients or internal systems may be relying on deprecated APIs without the company knowing. You need to thoroughly check your systems and use analytics to find these.
– Migration burden vs. benefits: The effort of providing new paths, tools, support, and monitoring for migration must be worth the benefits of deprecating the old API.
– Timing & compatibility windows: Removing an API too early can break clients, while waiting too long can slow down progress. You need to find a balance between stability and evolution.

Lifecycle phases & key milestones

Planning / deprecation planning

This is the first phase, where you prepare before telling anyone about the changes. You need to decide which APIs or features will be deprecated and choose a final date for their removal. You should make sure that the new API version is stable and create all the necessary documents and support guides for developers. You also need to work out who will be affected by the change and track how much they are using the old API.

Deprecation announcement

This is when you formally tell users that an API is going away. You should publish notices on your developer portal, in emails, in your changelog, or on your blog. The API’s documentation should be updated to show that it is deprecated, and you should add warnings to the API’s responses. Throughout the transition period, you should send regular reminders to users.

Grace / transition period

This is the time you give clients to update their code. The old API will still work, but no new features will be added. You should monitor how the old API is being used and provide support to developers, including sample code and SDK updates. In some cases, you might gradually throttle new usage to encourage faster migration.

Deprecation day / flagging

This is when the API is officially flagged as deprecated. All responses from the old API should include a warning, and the documentation should fully alert users to the deprecation. The support team should be ready to help with migration efforts.

Sunset / removal / retirement

This is when you completely remove the old API or endpoint. When clients try to use it, they will get error codes like 410 Gone or 404 Not Found. You can also set up redirects to the new API. After the API is removed, you should clean up any old resources, revoke access, and get rid of old code and data.

Post-deprecation support & review

After the old API is gone, you should deal with any remaining support tickets and then review what went well and what could be improved. You should use these insights to inform your future API policies. If you have a special agreement with certain key users, you may continue to offer them limited support.

Technical & design considerations

When deprecating an API, you have to think about some critical technical and design decisions. This is to ensure a smooth, transparent, and manageable transition for your users.

Versioning strategy

– Choose a scheme: You should choose a way to version your API, such as adding a version number to the URL or a header, and use it consistently.
– Be clear: Make sure the new version is stable before you deprecate older ones. You should also clearly state in your API documents which versions are supported and which are deprecated.

Backward compatibility & graceful degradation

– Avoid breaking changes: During the deprecation period, you should try to avoid making changes that will break existing clients.
– Gradual deprecation: If changes are necessary, you can try to deprecate them in stages. For example, you can deprecate individual fields first and then the full endpoints later.
– Use fallback logic: You should use a system that supports clients in the middle of a migration so they don’t break.

Deprecation headers & metadata

– Use HTTP headers: You can use headers such as Deprecation to let clients know that an API is being phased out, and Sunset (as per RFC 8594) with the date when it will no longer be available. You can also use a Warning header to provide more details.
– Update API specifications: In your API’s specifications, such as OpenAPI, you should mark operations or paths with deprecated: true.

Documentation & discovery

– Clear documentation: You should clearly mark deprecated endpoints or versions in your documentation with banners or labels.
– Provide a migration guide: You should create a guide that shows a side-by-side comparison of the old versus new API, code snippets, and common pitfalls. You should also provide a map that shows which old endpoints correspond to the new ones.

Monitoring, telemetry & analytics

– Continuous monitoring: You should continuously monitor the usage of deprecated API endpoints to see how migration is progressing.
– Adjust timelines: You should use these metrics to send more reminders or to adjust the deprecation timeline.

Throttling, rate limits & access control (optional)

– Gradual restrictions: You can gradually restrict or throttle features on the old API to encourage migration while still keeping the core functionality.
– Stricter policies: Before the old API is fully removed, you can enforce stricter access policies.

Error handling & response behaviour post-deprecation

– Return clear error codes: After the sunset date, you should return clear status codes, such as 410 Gone, with a message that directs users to the new API.
– Provide helpful error payloads: In the error response, you can include a link to your migration documents or version information.

Migration tools & support

– Provide tools: You can provide SDKs, client libraries, or helper wrappers that make the transition easier.
– Offer scripts: You should offer scripts or code snippets that can help to automate the migration.

Decommissioning & cleanup

– Plan for cleanup: You should have a plan for removing old code, freeing up resources, and revoking permissions.
– Update infrastructure: You should update your infrastructure so that the deprecated endpoints can no longer be reached after the sunset date.
– Keep archival documentation: Instead of deleting old documentation, you should mark it as “deprecated / retired” so that existing users can still refer to it.

Communication & stakeholder coordination

Clear, timely, and multi-channel communication is essential for a successful API deprecation. Poor or inconsistent messaging is one of the biggest reasons for problems with migration and user dissatisfaction.

Stakeholder identification & roles

– Internal stakeholders: This includes people like product managers, engineers, quality assurance, support, and marketing.
– External stakeholders / API consumers: This includes developers, partner companies, and third-party integrators who use your API.
– Operations / devops / API gateway teams: These teams are responsible for implementing deprecation headers and other rules.
– Communications / documentation teams: They are in charge of creating notices, web content, blog posts, and other content related to the deprecation.

Communication channels & tactics

– Developer portal / documentation updates: You should prominently flag deprecations, show timelines, and provide links to migration guides in your documentation.
– Email / direct notifications: You should target clients who are actively using the API, as well as token holders and API key owners.
– In-app / dashboard banners or notifications: This is a good way to prompt users who are logged into your API management console.
– Blog posts / changelogs / release notes: These are good for public announcements, explaining the reasons for the deprecation, the timeline, and the migration paths.
– Forums / developer community channels: These are good for questions and answers, feedback, and troubleshooting migration issues.
– Support / customer success outreach: You should proactively reach out to high-value clients who might need more help with migration.

Messaging best practices

– Be transparent & honest: Explain why you are deprecating an API, not just that you are doing so.
– Provide clear timelines & milestones: Include dates for key events, such as the announcement, the start of deprecation, and the final removal.
– Offer alternatives / migration paths: You should always provide a recommended replacement or a new version of the API.
– Frequent reminders / follow-ups: You should send reminders regularly, especially as you get closer to the final removal date.
– Tailor communication: You should use more detailed and technical language for developers and higher-level language for business stakeholders.
– Make support visible: You should clearly publish your support channels and a frequently asked questions page.

Internal coordination & governance

You should create a deprecation working group to coordinate between all the teams. This group should have regular meetings to monitor migration progress, address any blockers, and review feedback. A shared dashboard that shows which clients have migrated and who has not is also useful.

Risks & mitigations in communication

– Stakeholders miss notices: You can mitigate this by using multiple channels, segmenting active clients, and sending reminders.
– Messaging inconsistency: You can mitigate this by using approved templates and centralising content.
– Overwhelming users: You can prioritise high-impact clients, schedule messages, and throttle notifications.
– Negative user reaction / trust erosion: You can mitigate this by being empathetic, providing a clear reason for the change, and extending timelines if needed.
– Undiscovered consumer dependencies: You can mitigate this by doing an early direct outreach to critical clients and using analytics to identify who is impacted.

Sportmonks: A real-world example of API deprecation

Sportmonks is a provider of sports data APIs. Our approach to moving from API 2.0 to API 3.0 is a practical case of how to manage API deprecation.

Deprecation in action

– Active deprecation of API 2.0: Our documentation clearly labels our Football API v2 as deprecated. We have committed to keeping it working until at least the end of 2025, which gives clients a long time to switch.
– Transition to API 3.0: We introduced API 3.0 with new endpoints, data models, and more features. We have also documented the differences to help with migration, for example, the removal of localTeam and visitorTeam in favour of a combined participants include.
– Deprecation metadata & communication: In our documentation, We label v2 as “deprecated” and clearly mark new features for v3.
– Migration timeline & support: We provide migration guides and keep both APIs running during the overlap period. This phased approach gives users enough time and transparency.

Lessons illustrated by Sportmonks

– Explicit deprecation labelling is critical: By marking v2 as deprecated and providing a clear transition window, we reduced confusion for users.
– The overlap period matters: Keeping v2 active while pushing v3 meant that clients were not forced into abrupt changes.
– Explaining the rationale is important: Explaining the reasons for the change helps clients understand why they need to migrate.
– Detailed documentation is essential: The detailed migration documentation and guides were crucial for clients to have confidence in the process.
– Phased innovation: By only adding new features to v3, they put pressure on users to migrate while keeping the system manageable.
– Consistent communication: Consistent communication through documentation and blogs ensured that clients were informed and prepared.

Manage API transitions smoothly with Sportmonks

As technology evolves, API versions need to be updated, replaced, or retired. Sportmonks handles this transition transparently through clear documentation, migration guides, and long overlap periods between versions. Our move from Football API 2.0 to 3.0 is a prime example, version 2.0 remains operational until at least the end of 2025 while 3.0 introduces new endpoints, data models, and features. Start your free trial with the Sportmonks Football API and experience a modern, future-ready data platform built on clarity, stability, and trust.