10 REST API Pagination Best Practices

Pagination is a common requirement when working with REST APIs. It allows you to retrieve a subset of data from a large dataset, which can be especially useful when working with large datasets that might not fit in memory or when you want to retrieve only the data that is relevant to the current operation.

There are a few different ways to implement pagination in a REST API, and there are also a few different best practices to keep in mind when doing so. In this article, we will discuss 10 of the most important pagination best practices for REST APIs.

1. Use a standard approach

If you use a standard approach, it will be much easier for developers who are consuming your API to understand how to paginate through the data. They won’t have to guess or try to reverse engineer your pagination scheme; they’ll already know what to expect.

There are many different ways to paginate data in a REST API, but one of the most popular is using the Link header. The Link header contains links to the first, last, next, and previous pages of data. This makes it easy for developers to navigate through the data without having to make multiple requests.

If you’re not using the Link header, make sure you document your pagination scheme so that developers can easily understand it.

2. Provide links to the next and previous pages of results

When a user makes a request to your API, they should only receive the data that they need to consume at that moment. This not only saves bandwidth on their end, but also reduces the amount of time it takes for them to receive a response from your API.

However, in some cases, a user might need more data than what you can provide in a single response. In these cases, it’s important to provide links to the next and previous pages of results so that the user can easily fetch the additional data they need.

Not only does this make it easy for the user to get the data they need, but it also helps to reduce the load on your API servers by allowing the user to fetch the data in smaller chunks.

3. Include information about the total number of items available

Suppose a client makes a request to your paginated API endpoint and receives 100 results. The client then makes another request, specifying a different page size of 200. If the total number of items available is less than 200, the client will receive an error response indicating that there are no more results.

However, if you include information about the total number of items available in the API response, the client can adjust their page size accordingly. This way, the client can always make requests that are guaranteed to return results, without having to trial-and-error their way to the right page size.

Including the total number of items available also allows clients to accurately calculate how many pages of results they can expect. This can be useful for building UI elements like pagination controls.

4. Allow filtering, sorting, and other operations in the query string

When a client makes a request to a paginated API endpoint, they should be able to control the amount of data that is returned to them. This means being able to specify how many results per page they want, as well as what fields they want included in the response.

Additionally, clients should be able to control the order of the results that are returned to them. This is especially important when dealing with large result sets, as it can help the client narrow down the data that they are interested in.

Finally, clients should also be able to perform other operations on the data that is returned to them. This could include things like filtering the results by certain criteria, or even calculating aggregate values.

All of these operations can be performed using query parameters in the URL. By allowing clients to control the data that is returned to them in this way, you can make your API much more flexible and user-friendly.

5. Consider providing an endpoint that returns all results

When you provide an endpoint that returns all results, it’s much easier for developers to get started with your API. They don’t have to make multiple requests to get the data they need, which saves time and effort.

It also makes it easier to debug your API. If there are any problems with pagination, developers can easily see all of the data that’s being returned, which makes it easier to identify the issue.

Finally, it provides a fallback option for when pagination doesn’t work as expected. For example, if a developer makes a request for page 2 but only page 1 is returned, they can still get the data they need by making a request to the all results endpoint.

6. Support pagination for large result sets

When a REST API endpoint doesn’t support pagination, the client has to fetch the entire result set in one go. This can take a long time, especially for large result sets, and might even time out.

On the other hand, when a REST API endpoint does support pagination, the client can fetch the results in smaller chunks, which is much more efficient.

There are two main ways to implement pagination in a REST API: offset-based pagination and cursor-based pagination.

Offset-based pagination is the most common type of pagination, and it works by returning a specific number of results starting from a given offset. For example, if you have a result set of 100 items and you want to return 10 items per page, you would use offset-based pagination with an offset of 0 for the first page, an offset of 10 for the second page, and so on.

Cursor-based pagination, on the other hand, works by returning a specific number of results starting from a given cursor position. Cursor positions can be any arbitrary value, but they are typically based on some kind of ordering (for example, chronological or alphabetical).

One advantage of cursor-based pagination over offset-based pagination is that it allows you to change the order of the results without affecting the pagination. With offset-based pagination, on the other hand, changing the order of the results would require recalculating the offsets, which would be a major pain for the client.

Another advantage of cursor-based pagination is that it allows you to easily support “infinite scroll” UIs, where new results are loaded automatically as the user scrolls down. With offset-based pagination, on the other hand, you would need to keep track of the scroll position, which would be much more complicated.

7. Don’t use offset-based pagination

With offset-based pagination, the client specifies an offset and a limit, and the server returns that number of items starting from the offset. So if the client requests items 0-9 (offset 0, limit 10), the server would return items 1-10. If the client then requested items 10-19, the server would return items 11-20, and so on.

The main problem with offset-based pagination is that it’s not very efficient. With each request, the client has to specify both the offset and the limit, which means that the server has to do a lot of work to calculate the correct data to return.

It’s much more efficient to use cursor-based pagination, where the client just specifies a cursor (usually in the form of a URL) and the server returns the next batch of items. Cursor-based pagination is also much easier to implement, since the server doesn’t have to keep track of offsets.

8. Limit the number of resources returned per page

If you don’t limit the number of resources returned per page, your API will likely return more data than what’s necessary, which can put a strain on your server. Not to mention, it can also make your API less responsive since it takes longer to process and return the data.

Ideally, you should limit the number of resources returned per page to around 100. This is a good balance between returning too much data and not enough data.

Of course, you can always adjust this number depending on your specific needs. If you find that 100 resources per page is too much for your server to handle, you can lower it to 50 or even 25.

9. Make sure your API is well documented

Your API documentation is the first place developers will look when they’re trying to figure out how to use your API. If your documentation doesn’t clearly explain how pagination works, developers are likely to get frustrated and give up.

Furthermore, well-documented APIs are more likely to be used by third-party developers, which can help increase adoption of your API.

Finally, if you ever need to make changes to your pagination implementation, having clear and concise documentation will make it much easier to communicate those changes to developers.

10. Test your API thoroughly

When you paginate data, you’re essentially breaking up a larger result set into smaller chunks that can be more easily consumed. This means that there are now multiple API calls that need to be made in order to retrieve all of the data.

If your API isn’t tested thoroughly, it’s possible that some of these calls could fail, resulting in incomplete data being returned to the client. This could lead to a poor user experience, and in some cases, could even cause data loss.

To avoid this, it’s important to write comprehensive tests for your API that cover all of the different scenarios that could occur when paginating data. Only by doing this can you be confident that your API will work as expected and that all of the data will be correctly retrieved.