How to Sunset an API

Sunsetting an API means retiring it permanently, often because it’s outdated, replaced, or poses security risks. Without proper planning, this process can disrupt users, harm trust, and lead to costly errors. Here’s how to handle it effectively:

Plan a Clear Timeline: Announce deprecation early (e.g., 6 months before shutdown). Set clear deadlines for migration and final removal.
Notify Users: Use blog posts, emails, developer portal banners, and webinars to communicate the changes.
Support Critical Users: Offer personalized help for key accounts and extend timelines if needed.
Use HTTP Headers: Implement Sunset, Deprecation, and Link headers to notify users programmatically.
Schedule Brownouts: Temporarily disable the API to test user readiness and gather feedback.
Return HTTP 410: After shutdown, use the HTTP 410 status code to signal permanent removal, along with clear error messages and migration guides.

Properly managing API sunsetting ensures a smooth transition, minimizes disruptions, and maintains trust with users.

API Lifecycle Management: Deprecation and Sunsetting#

Many of you might conflate the concepts of API deprecation and sunsetting. Here's a video from our good friend, Erik Wilde, to explain the difference:

tl;dw - Deprecation is the process of indicating that a given endpoint or API should not be used anymore, whereas sunsetting is the process of making that endpoint or API unusable. Deprecation precedes sunsetting. Check out our full guide to deprecating REST APIs to learn more about API deprecation.

How to Plan Your API Sunset Timeline#

Creating a structured timeline is essential for a smooth API deprecation process. It gives users enough time to migrate while ensuring a firm shutdown date. A good plan combines clear deadlines, effective communication, and focused support for critical users. This timeline sets the stage for implementing technical deprecation signals and support strategies in later steps.

Setting Important Dates and Deadlines#

Your API sunset plan revolves around three key milestones: the deprecation announcement, the migration period, and the final shutdown. Each milestone helps guide users through the transition.

Announce the deprecation at least six months before the shutdown to give users ample time to prepare. For instance, if you announce on March 15, 2025, you might set a soft deadline for July 15, 2025, and finalize the shutdown on September 15, 2025. This phased approach allows you to identify users who need extra help and fine-tune your support efforts as the deadline nears.

Understanding API usage patterns and engaging directly with important clients during this period is crucial.

The final shutdown date is when the API stops functioning entirely. Once announced, this date should remain fixed to maintain user trust and ensure effective planning. However, it’s wise to build in an internal buffer to handle any unexpected issues.

How to Notify API Users and Teams#

Clear communication is vital during the sunsetting process. Start with a blog post explaining the reasons for the deprecation, the timeline, and the migration steps. Follow this with direct email notifications to all registered API users, including both technical contacts and account managers.

Update your API documentation with clear deprecation warnings on affected endpoints, and add banner notifications to your developer portal during the sunset period. Hosting live webinars or Q&A sessions can also help clarify migration requirements.

Ensure consistent messaging across all communication channels. Internally, inform your customer success, support, and sales teams well in advance so they’re prepared to handle user inquiries. Providing internal documentation that explains the migration process in both technical and business terms can further empower your teams.

Timing matters, too. Avoid making announcements during major holidays or busy industry events to ensure your message gets the attention it deserves.

Providing Extra Support for Mission-Critical Users#

Once users are notified, focus on supporting those most impacted. Identify mission-critical accounts based on factors like usage, revenue, or strategic importance, and reach out to them individually before the public announcement.

Offer personalized support, such as dedicated channels, live chats, or one-on-one consultations, to help these users transition smoothly. For those with complex systems, consider extending the deprecation period on a case-by-case basis. If you do, make sure the extension is time-limited and clearly communicates the final migration deadline.

Set up a dedicated support channel specifically for sunset-related questions to keep these inquiries separate from regular support requests. Training your support team on the migration process ensures they can provide quick, effective assistance without escalating every issue to engineering.

For large user bases, a phased or rolling shutdown can be helpful. Migrating users in batches not only manages support workloads but also allows you to adjust the process based on early feedback.

The goal is to ensure that your most important users feel supported throughout the transition. A smooth migration experience reduces disruptions and can even strengthen long-term relationships as users adopt your new API version.

Using HTTP Headers to Signal API Deprecation#

HTTP headers offer an automated way to notify client applications about API deprecations. When used effectively, these headers ensure that all API consumers - whether or not they read email updates or documentation - receive deprecation notices and can plan accordingly. This approach works well alongside other notification methods like timelines and direct client communication.

How to Implement the Sunset Header#

The Sunset header is designed to inform clients about the date when an API endpoint will no longer be available. As outlined by the IETF, this header specifies that a URI is expected to become unresponsive after a particular date. To ensure compatibility across systems, the date must follow the RFC 1123 format.

"The Sunset HTTP header signals that a URI will become unresponsive at a specified future date." - IETF

Here’s an example of how to format the Sunset header:

Sunset: Sat, 25 Jul 2020 23:59:59 GMT

Include this header in every response from the deprecated endpoints. Consistency is key - apply it universally across all affected responses. Additionally, make sure to document the Sunset header in your API documentation so that clients can detect and handle deprecation automatically.

Adding Deprecation and Link Headers#

To provide even more clarity, you can pair the Sunset header with additional headers like Deprecation and Link. The Deprecation header explicitly marks an API as deprecated, signaling to clients that the endpoint is on its way out. Meanwhile, the Link header can point to a dedicated deprecation policy page that explains why the change is happening and provides guidance for migration.

Here’s an example of how these headers might look together:

Deprecation: Sat, 1 Aug 2020 23:59:59 GMT
Link: <https://api.endpoint.com/deprecation>; rel="deprecation"; type="text/html"

When combined with the Sunset header, a complete response might look like this:

Deprecation: Sat, 1 Jul 2020 23:59:59 GMT
Sunset: Sat, 25 Aug 2020 23:59:59 GMT
Link: <https://api.endpoint.com/deprecation>; rel="deprecation"; type="text/html"

Make sure all dates align across your headers and other communications to avoid confusion.

Marking Deprecated and Sunset Endpoints in Documentation#

As soon as you implement deprecation headers, update your API documentation to reflect these changes. Clearly label each deprecated endpoint with its deprecation and sunset dates, and include links to migration resources.

Provide a clear explanation for the deprecation - whether it’s due to security upgrades, improved performance, or a shift in architecture. This helps users understand the benefits of moving to the new solution. Additionally, create detailed migration guides that walk users through the transition. Include practical elements like code examples, parameter mappings, and troubleshooting advice.

For major changes, you may also want to include deprecation warnings directly in API responses. Just ensure these warnings don’t interfere with existing client functionality.

Sunsetting is pretty controversial in the API space, with many companies never actually shutting down old API endpoints out of principle. If you do plan on shutting down an endpoint, provide specific reasons as to why the API cannot continue operations.

Using API Brownouts to Prepare Clients for Shutdown#

API brownouts are a practical way to test how ready your clients are for an upcoming shutdown. Unlike a permanent shutdown, these planned, temporary outages allow you to see which integrations still rely on deprecated endpoints. They also provide valuable insights to help you fine-tune your migration support.

The process is straightforward: you disable the deprecated features for a short time - anywhere from a few minutes to a few hours - and then bring them back online. During these outages, the API delivers clear error messages with migration instructions, ensuring clients know what steps to take.

How to Schedule and Announce Brownouts#

Start by analyzing your API's usage patterns to find times when the deprecated features are least active. Scheduling brownouts during off-peak hours - like early mornings or late evenings based on your primary users' time zones - helps minimize disruptions.

As the final shutdown date approaches, gradually increase the frequency and duration of the brownouts. For instance, you could begin with 15-minute sessions once a week, then move to 30-minute brownouts twice a week, and eventually extend them to daily hour-long outages in the final weeks.

Communicate your brownout schedule well in advance using multiple channels like email, developer portals, and API documentation. Be specific with dates and times, using clear formats. For example: "Brownouts will occur on Tuesday, March 15, 2025, from 2:00 AM to 2:30 AM PST."

Make sure your error messages during brownouts are clear and actionable. Instead of generic error codes, provide detailed guidance, including links to migration resources, alternative endpoints, and support contact information. Tools like Zuplo's Brown Out Policy allow you to customize error responses to effectively notify clients about what’s happening and what they need to do. Here's an example on how to implement a brownout using Zuplo:

What to Track During Brownout Periods#

Monitoring brownouts gives you a wealth of information about your API’s dependencies, helping you prepare for the final shutdown. Here are key areas to focus on:

API Call Volume: Keep track of requests hitting deprecated endpoints, broken down by client or company. This helps you identify who still relies on the old features and prioritize outreach.
Error Patterns: Look for endpoints with high error rates and failing request types. These patterns can reveal which features clients are struggling to replace.
Service Dependencies: Watch for failures in related services that depend on your deprecated API. These issues might not be obvious during normal operations but can surface during brownout testing.
Revenue Impact: Assess potential revenue risks from clients who continue using deprecated features. This can help you decide whether to extend timelines for high-value customers or enhance migration support for them.

To make sense of this data, build detailed analytics dashboards. Segment the information by client, endpoint, and time period to uncover patterns, like clients repeatedly accessing deprecated endpoints without implementing proper error handling or migration strategies.

Using Brownout Data to Improve Migration Support#

Brownouts often highlight migration challenges that standard deprecation processes might miss. Use the insights you gather to make targeted improvements:

Support Struggling Clients: Identify users who frequently encounter errors during brownouts and reach out with personalized support, leveraging your API analytics.
Revise Documentation: If specific endpoints fail repeatedly, enhance your migration guides with detailed examples, troubleshooting tips, or alternative solutions.
Refine Error Messages: If you notice a spike in support requests with similar questions, update your error messages to provide clearer, more specific instructions.
Adjust Timelines: If key clients continue using deprecated features heavily, consider extending your sunset timeline or offering additional migration resources.
Target Specific Groups: Use your data to identify clusters of users who still rely on deprecated features. Tailor your communication and support efforts to help these groups transition more effectively.

Brownout testing doesn’t just help with the current migration - it provides valuable feedback for future API changes. If clients struggle with certain aspects of your new API, you can use this information to make improvements, ensuring a smoother process next time around.

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Implementing HTTP 410 for Final API Removal#

When permanently retiring an API, using HTTP 410 responses is a crucial step. This status code, unlike the more common 404 error, clearly signals that a resource is gone for good. It helps developers understand the endpoint is no longer available and prompts search engines to remove the URLs from their indexes faster. Additionally, it discourages clients from continuing to make requests to these endpoints, saving resources on both ends.

Setting Up HTTP 410 Responses#

To implement HTTP 410, update your server or application code to return this status for all deprecated endpoints. The exact configuration will depend on your specific infrastructure, but the process usually follows the same principles.

Start by identifying all endpoints slated for removal. Create a list of URL patterns, methods, and routes that need to return the 410 status. Depending on your setup, you might:

Modify the .htaccess file for Apache servers.
Adjust server configurations for NGINX.
Use policy settings in your API gateway.

Here’s an example of a 410 response for a removed endpoint:

HTTP/1.1 410 Gone
Content-Type: application/json
Date: Tue, March 15, 2025, 10:30:00 GMT

{
  "error": "This API endpoint has been permanently removed",
  "message": "The /v1/legacy-users endpoint was sunset on March 1, 2025",
  "migration_guide": "https://docs.yourapi.com/migration/v2-users",
  "support_contact": "api-support@yourcompany.com"
}

After configuring the responses, test each endpoint using HTTP checkers or automated scripts to ensure they consistently return the 410 status. Verify that your error messages are clear and follow a consistent format across all endpoints.

Writing Helpful Error Messages#

A well-crafted error message can significantly ease the transition for developers. While HTTP status codes provide technical details, they don’t always offer enough context. Your error messages should include:

The removal date of the endpoint.
A brief explanation of why it was removed.
Clear instructions for next steps, such as migration guides or support contacts.

By consistently structuring your error responses with fields for error type, a human-readable message, migration resources, and support contact details, you help developers handle these changes more effectively.

Updating Documentation After API Removal#

Once HTTP 410 responses are in place, promptly update your API documentation to reflect the changes. Leaving outdated information in the documentation can confuse developers and lead to unnecessary support requests.

Start by removing references to deprecated endpoints. Replace them with notices about the removal, including the sunset date and migration details.

Consider creating a "Deprecated Endpoints" section in your documentation. List all removed functionality along with their sunset dates, and include migration guides with code samples in multiple programming languages. Update the[API changelog or release notes to document the exact dates when 410 responses were implemented, which endpoints were affected, and where developers can find migration resources.

Additionally, review internal links and cross-references to ensure they no longer point to removed endpoints. Update code examples, tutorials, and quickstart guides to reflect current API versions. Prominent notices on your developer portal about recent changes can also help keep developers informed, especially if widely used endpoints are affected.

Tools and Best Practices for API Sunsetting#

Successfully retiring an API takes more than just sending HTTP status codes and notifications. By combining effective tools with well-thought-out practices, you can ease the transition for developers, maintain trust, and minimize the support burden.

Building Complete Migration Guides#

A well-structured migration guide is essential for a smooth API sunset. It should clearly compare the old and new endpoints, detailing the exact changes developers need to implement. Include specifics about each endpoint's functionality, the data they handle, and any dependencies - whether upstream or downstream - that could impact the migration process. This level of clarity helps you create realistic timelines and avoid surprises during the transition.

Break the migration process into manageable tasks with clear deadlines. To make it even easier, provide side-by-side code examples that highlight the differences between the old and new API calls. For instance, if you're transitioning from /v1/users to /v2/users, include examples in widely-used languages like JavaScript, Python, and cURL.

Keep everyone in the loop by regularly updating your documentation and communicating the migration plan to both your internal team and external API users. The guides should also address potential errors, explaining common HTTP error codes and how to handle them. Highlight any new API features - like filtering, sorting, or pagination - that improve performance. These detailed resources set both your team and users up for success during the transition.

Testing New API Versions Before Retirement#

Thorough testing of the new API is a crucial step before retiring the old one. Develop a testing strategy that ensures the replacement matches the original in terms of functionality and performance. Use real-world scenarios to create test cases with established frameworks, helping you quickly identify any issues.

To ensure a seamless transition, focus on backward compatibility and aim to minimize downtime. Stick to best practices, such as using logical nesting for endpoints, maintaining consistent naming conventions (like favoring nouns over verbs), and implementing strong security and caching mechanisms. These steps not only make the transition smoother but also provide a solid foundation for the new API version.

How Zuplo Simplifies API Sunsetting#

Zuplo's API management platform offers tools that make the sunsetting process much easier.

Zuplo is OpenAPI-native, which means you can directly document your sunset headers or 410 responses in your spec. Not only will this ensure your autogenerated developer docs are updated, but you can also enforce your APIs actually send back these responses and headers at the gateway level (aka contract testing).

Zuplo has a fully programmable policy engine, which allows you to scale common, custom building blocks like API brownout behavior, sunset responses, and more across all of your sunset endpoints.

Beyond these capabilities, Zuplo offers robust tools for security, route registration, schema validation, and authentication/authorization. This ensures consistent behavior across both legacy and new API versions. With its analytics and monitoring features, Zuplo provides valuable insights into usage patterns, helping you make informed decisions about migration timelines and strategies.

Conclusion: Your API Sunsetting Checklist#

Sunsetting an API takes thoughtful planning, clear communication, and the right tools. Rajat Malik from Siemens highlights the importance of transparency:

"Effective management of API feature deprecation hinges on clear and timely communication with API consumers. Prioritize transparent communication by informing them about reasons, timelines, and alternatives for deprecated features, supplemented with comprehensive documentation and support." - Rajat Malik from Siemens

Start by mapping out a detailed timeline. Announce the deprecation well in advance - ideally several months - while setting clear deadlines for each phase, from the initial announcement to the final removal. Use a mix of communication channels like emails, blog posts, and developer portals to ensure your message reaches all stakeholders.

Incorporate HTTP sunset headers as soon as deprecation begins. These headers provide machine-readable alerts to users. Follow up with direct emails to active users of the deprecated endpoints, offering personalized support to help them navigate the transition.

Keep an eye on API usage data through analytics. If you notice high usage persisting, it might be time to revisit your communication strategy. Provide clearer alternatives, refine your messaging, or even adjust your timeline if necessary.

When the time comes for final removal, implement HTTP 410 status codes to signal the change. Include helpful error messages that guide users toward available alternatives. Update your documentation promptly to reflect the changes, and maintain an open feedback loop to tackle any lingering issues.

Throughout the process, focus on communication, consistency, and collaboration. Keeping open lines of communication with your customers and partners not only eases the transition but can also uncover ways to improve your API and strengthen relationships.

Ultimately, successful API sunsetting is a collaborative effort, not a unilateral decision. Tools like Zuplo’s programmable policies and built-in brownout support can help streamline the process while maintaining user trust.

FAQs#

What is the best way to notify users about API deprecation to minimize disruption?#

When planning to phase out a feature or service, it's important to announce the deprecation as early as possible, giving users plenty of time to prepare. Clearly communicate the timeline, including key dates, so everyone knows what to expect. Use sunset headers to programmatically highlight the deprecation date, and follow up with multiple reminders through email or other communication channels.

To make the transition smoother, provide comprehensive migration guides that walk users through the necessary steps. Be transparent throughout the process - keep users updated regularly and make sure they know help is available. Offering prompt support to address questions or concerns can go a long way in easing the change.

What are API brownouts, and how can they help prepare clients for an API shutdown?#

API brownouts are short, planned service interruptions designed to mimic outages, giving clients a chance to prepare for an API's eventual shutdown. By temporarily reducing or halting specific functionalities, these brownouts let clients test their systems, uncover dependencies, and confirm they’re ready for the change.

This step-by-step process allows clients to adjust, explore alternatives, and fix any issues before the API is permanently retired. Brownouts also act as a clear warning that the API’s end-of-life is near, prompting timely action and reducing the risk of major disruptions.

How do HTTP headers help in retiring an API, and how can they be used effectively?#

HTTP headers like Sunset and Deprecation play a key role in managing the retirement process of an API. They ensure clients are informed about upcoming changes and provide the necessary timelines to plan accordingly.

The Deprecation header indicates that an API is on its way out, while the Sunset header specifies the exact date and time when the API will no longer be available. Including these headers in API responses gives clients ample warning to adapt - whether that means migrating to a newer version or phasing out integrations. This proactive communication minimizes disruptions and helps maintain a seamless experience for users.

Tags:#API Lifecycle Management