10 REST API Caching Best Practices

Caching is a technique that stores frequently accessed data in a location that is faster to access than the original data source. Caching can be used to improve the performance of a REST API by reducing the number of requests that need to be made to the API server.

There are a number of different caching strategies that can be used, and the best strategy to use will depend on the specific needs of the API. This article discusses 10 of the most common caching strategies and provides guidance on when each strategy should be used.

1. Use a Cache-Control Header

The Cache-Control header is a HTTP header that tells the client (or browser) how long it can cache a particular resource. This header can be used to tell the client to cache the resource for a certain amount of time, or to never cache the resource.

For example, let’s say you have a REST API that returns data about users. Each time a client makes a request to this API, the server has to fetch the data from the database. This can be slow, especially if there are a lot of clients making requests.

If you add a Cache-Control header to the response, you can tell the client to cache the data for a certain amount of time. This means that the next time a client makes a request, it can just use the cached data instead of making a new request to the server. This can speed up the process and reduce the load on your server.

You can also use the Cache-Control header to tell the client not to cache the resource at all. This is useful if the data is likely to change often, such as in an e-commerce site.

To sum up, using a Cache-Control header is a great way to improve the performance of your REST API. It can help reduce the load on your server and make your API faster for clients.

2. Make Your Content Cacheable by Default

If you don’t make your content cacheable by default, then every time a client makes a request to your API, the server has to go and fetch the data from the database. This is not only inefficient, but it also puts unnecessary strain on your database.

On the other hand, if you do make your content cacheable by default, then the first time a client requests data from your API, the server will fetch it from the database and cache it. Subsequent requests for that same data will be served from the cache, which is much faster and more efficient.

There are a few different ways to make your content cacheable by default. One way is to use the HTTP Cache-Control header. The Cache-Control header allows you to specify how long a piece of content should be cached for. For example, you could set the Cache-Control header to “public, max-age=3600” which would tell the client that the content can be cached publicly for up to one hour.

Another way to make your content cacheable by default is to use the ETag header. The ETag header is a bit like a fingerprint for a piece of content. When a client makes a request to your API, the server can send back an ETag header with the response. The client can then store this ETag value and use it in subsequent requests. If the content hasn’t changed, then the server can just return a 304 Not Modified status code, which tells the client that it doesn’t need to bother fetching the content again because it already has the latest version.

One last thing to keep in mind is that even though making your content cacheable by default is a good idea, there are still some cases where it doesn’t make sense. For example, if you have an API that returns sensitive user data, then you probably don’t want to cache that data by default. In those cases, you can use theCache-Control header to explicitly mark the content as “private” so that it won’t be cached.

3. Set an Expires or Max-Age Header

When a client makes a request to a server, it will cache the response. The next time the same client makes a request for the same resource, it will first check its cache to see if a cached copy exists and is still valid before making a new request.

If there is no Expires or Max-Age header set, the client has no way of knowing how long the cached copy is valid for. As a result, it will have to make a new request to the server every time it wants to access the resource, even if a cached copy exists.

By setting an Expires or Max-Age header, you can tell the client how long the cached copy is valid for. This way, the client can use the cached copy without having to make a new request to the server every time.

It’s important to note that the Expires header should only be used for resources that don’t change often. For resources that do change frequently, the Max-Age header should be used instead.

4. Don’t Forget the ETag Header

An ETag is a unique identifier that represents the current state of a resource. When a client makes a request to a server for a resource, the server includes an ETag header in the response. The client can then cache the resource and, on subsequent requests, include the ETag in the If-None-Match header.

If the resource hasn’t changed, the server will respond with a 304 Not Modified status code and no body. This allows the client to serve the cached version of the resource, which saves time and bandwidth.

If you forget to include the ETag header in your responses, clients won’t be able to take advantage of this caching optimization. So, make sure to always include ETags in your REST API responses!

5. Consider Using Last-Modified and If-Modified-Since Headers

The Last-Modified header is used to indicate the date and time at which the resource was last modified. The If-Modified-Since header is used to make a conditional request; if the resource has not been modified since the specified date and time, then a 304 Not Modified response is returned instead of the resource itself.

Using these headers can be very beneficial in terms of performance because it allows the client to cache the resource and avoid making unnecessary requests for resources that have not changed. It also reduces the amount of data that needs to be transferred over the network, which can further improve performance.

6. Leverage Browser Caching for Static Assets

When a client makes a request to a server for a particular resource, the server will check to see if it has the most up-to-date version of that resource. If not, it will fetch the latest version from the origin server. This process can be time-consuming, especially if the client is on a slow internet connection.

Browser caching allows the client to store a local copy of the resource so that it doesn’t have to request it from the server every time it needs it. This speeds up the process and reduces the load on the server.

To take advantage of browser caching, you need to set the cache-control and expires headers for your static assets. The cache-control header tells the client how long it can keep the resource before it needs to check for an updated version. The expires header tells the client when the resource will no longer be valid and needs to be refreshed.

You can set these headers using a web server or a content delivery network (CDN). Once they’re set, the client will automatically cache the resources and serve them from the cache when requested.

7. Take Advantage of CDN Caching

CDNs are designed to cache and serve content from locations that are close to the user’s geographic location. This results in faster loading times and reduced latency.

Additionally, CDNs can cache static assets as well as dynamic content. So, if you have a REST API that returns JSON data, you can configure the CDN to cache that data. This way, subsequent requests for that data will be served from the CDN, which will improve performance.

To take advantage of CDN caching, you need to ensure that your REST API is configured to set the correct Cache-Control headers. These headers tell the CDN how long to cache the content and whether or not it can be cached.

Configuring the Cache-Control headers correctly can be tricky, so it’s best to consult with a CDN expert before making any changes.

8. Compress Textual Responses

When you compress textual responses, you can reduce the size of the response by up to 80%. This has two main benefits.

The first is that it reduces the amount of data that needs to be transferred, which can improve performance.

The second is that it reduces the amount of storage that is required on the server. This can free up resources and improve performance even further.

To compress textual responses, you need to use an encoding algorithm such as gzip. Gzip is a widely used compression format that is supported by most clients and servers.

To compress a response using gzip, you simply need to set the Content-Encoding header to gzip. You can then compress the response body using the gzip algorithm.

Once the response has been compressed, the client will automatically decompress it.

9. Add Versioning to Your URLs

When you make changes to your API, those changes can potentially break existing integrations that clients have built. By adding versioning to your URLs, you can maintain backwards compatibility while still being able to deploy new features and updates.

For example, let’s say you have a REST API with the following URL:

https://example.com/api/v1/users

If you make any breaking changes to this API, you can simply create a new version (e.g. v2) and deploy the updated API to that URL. Then, clients can continue to use the old API (v1) while they update their integrations to use the new API (v2).

This is a much better solution than having to support multiple versions of your API indefinitely.

10. Implement HTTP/2 Server Push

HTTP/2 Server Push allows a server to push resources to a client before it has even requested them. This is especially useful for resources that the client is likely to need, such as CSS and JavaScript files.

By pushing these resources to the client ahead of time, the client can start loading them immediately, without having to wait for the server to respond to its request. This can significantly improve page load times, especially on slow connections.

To implement HTTP/2 Server Push, you’ll need to use a web server that supports HTTP/2. Once you’ve done that, you can use the Link header to push resources to the client. For example, to push a CSS file to the client, you would include the following header in your response:

Link: ; rel=preload; as=style

You can also push multiple resources at once by including multiple Link headers.