10 REST API Payload Size Best Practices
If you're building a REST API, there are some best practices you should follow to make sure your API is well-designed, efficient, and scalable.
When designing a REST API, one of the first decisions you need to make is what format the API will use for its payloads. There are a number of different options available, but not all of them are equally well suited for all purposes. In this article, we’ll take a look at 10 different payload size best practices to help you make the best choice for your API.
1. Use the correct HTTP method
When you’re making a request to a REST API, the method you use will determine the size of the payload that’s sent in the request. For example, if you use the GET method, the entire payload will be sent in the URL. However, if you use the POST method, the payload will be sent in the body of the request.
This may not seem like a big deal, but it can have a significant impact on the size of the payload. In general, it’s best to use the POST method whenever possible. This is because the body of the request is not limited by the URL length, so you can send a larger payload.
Of course, there are exceptions to this rule. For example, if you’re sending a small amount of data, it may be more efficient to use the GET method. But in general, it’s best to err on the side of using the POST method.
2. Use JSON for request and response bodies
JSON is a lightweight data-interchange format that’s easy for humans to read and write, and easy for machines to parse and generate. This makes it ideal for use in REST APIs, which are often designed to be accessed by both humans and machines.
JSON is also less verbose than XML, so it results in smaller payload sizes. This is important because one of the key goals of a REST API is to be as efficient as possible, both in terms of bandwidth usage and processing time.
Finally, JSON has become the de facto standard for data interchange on the web, so there’s a good chance that your clients already have libraries available to help them work with JSON-formatted data.
3. Don’t return too much data in one call
If you return too much data in one call, it takes longer for the client to receive the response and start processing it. This can cause performance issues on the client-side, especially if the client is a mobile device with limited resources.
It’s also important to consider that not all of the data returned in one call will be used by the client. The client may only need a small subset of the data, but they have to receive and process the entire payload anyway.
To avoid these problems, it’s best to return the minimum amount of data needed to satisfy the request. If more data is needed, the client can make another API call to get the additional data.
4. Avoid returning nested objects
When an API returns a nested object, it’s effectively returning two pieces of information: the ID of the parent object, and the ID of the child object. The problem is that this can quickly become unwieldy as the number of levels of nesting increases.
Consider an API that returns a list of users, each of which has a list of friends, each of which has a list of friends, etc. If each level of nesting adds just one extra ID, then the total number of IDs returned by the API would be exponential.
To avoid this issue, it’s best to return flattened objects, or at least to limit the depth of nesting. In the example above, the API could return a list of users, each of which has an ID and a list of friend IDs. This would be much more efficient in terms of payload size, and would also be easier for clients to parse and work with.
5. Return metadata with responses
When an API request is made, the server will usually return more data than just the requested resource. For example, a GET request for a single user might return the user’s ID, name, email address, and other information.
This metadata helps the client understand the response and know what to do with the data. It also allows the client to cache the data and make subsequent requests more efficiently.
If the server doesn’t return metadata with its responses, the client has to make additional requests to get this information, which can be inefficient and slow down the overall performance of the API.
6. Implement filtering, sorting, and paging
When you’re dealing with large collections of data, it’s important to give your users the ability to filter that data down to only the most relevant results. For example, if you’re dealing with a large collection of blog posts, you might want to give your users the ability to filter by author, category, or date range.
Sorting is also important for large collections of data. This allows your users to control the order in which results are displayed. For example, they might want to see the most recent blog posts first, or the blog posts with the most comments first.
Finally, paging is important for large collections of data because it allows you to break up the results into smaller, more manageable chunks. This way, your users can easily navigate through the results without having to load an excessively large amount of data all at once.
All of these features (filtering, sorting, and paging) can be implemented in a variety of ways, but one of the most common methods is using query parameters in the URL. For example, you might have a URL like this:
https://example.com/api/posts?author=jane&category=news&sort=date&page=2
This URL would return the second page of results for all blog posts written by Jane in the category of news, sorted by date.
7. Version your API
As your API evolves over time, the size and structure of the payloads will change. If you don’t version your API, then existing clients will break because they will be expecting a different payload than what you are now sending.
By versioning your API, you can maintain backwards compatibility so that existing clients continue to work even as the payload changes. When you make breaking changes, you can increment the version number so that new clients know to expect a different payload.
Versioning also allows you to roll back changes if there are problems with the new payload. For example, if you release a new version of your API with a larger payload and find that it causes performance problems, you can quickly roll back to the previous version until you have time to optimize the new payload.
You can version your API in a number of ways, but the most common is to include the version number in the URL. For example, you might have a v1 and v2 version of your API, with the v2 being the default. Clients can then specify which version they want to use by including the version number in the URL.
8. Document your API
If you don’t document your API, it will be very difficult for developers to understand how to use it. This is because they won’t know what the endpoints are, what the parameters are, or what the response payloads look like.
Documentation is especially important if you have a large API with many endpoints and complex payloads. In this case, it’s essential to provide clear and concise documentation so that developers can easily find the information they need.
There are many ways to document an API, but one of the most popular methods is using Swagger. Swagger is a tool that allows you to create interactive documentation for your API. It’s easy to use and provides a great way for developers to familiarize themselves with your API.
9. Validate user input
If you’re not validating user input, then your API is susceptible to a number of different attacks, including denial of service (DoS) attacks, where an attacker sends a large amount of data to your API in order to overload your system.
Validating user input helps to ensure that only the data that you expect is being sent to your API, and that any data that is sent is in the correct format. This can help to prevent DoS attacks, as well as other types of attacks, such as SQL injection attacks.
There are a number of different ways to validate user input, but one of the most effective methods is to use a whitelist. With a whitelist, you specify the specific characters, or character sets, that are allowed in the data that is being sent to your API. Any data that does not match the whitelist is rejected.
Another effective method for validating user input is to use a blacklist. With a blacklist, you specify the specific characters, or character sets, that are not allowed in the data that is being sent to your API. Any data that matches the blacklist is rejected.
Both whitelists and blacklists can be effective at preventing malicious data from being sent to your API. However, whitelists are generally considered to be more secure than blacklists, as they are less likely to allow accidental inclusion of malicious data.
10. Handle errors gracefully
If an API request fails due to a size limit being exceeded, it’s important that the error message returned is clear and concise. The message should explain why the request failed and what the user can do to fix the problem. For example, a helpful error message might say something like “Your request failed because the payload exceeds the maximum size limit of 1 MB. Please reduce the size of your payload and try again.”
It’s also important to remember that not all 4XX status codes indicate an error on the part of the user. For example, a 404 status code indicates that the requested resource could not be found. In this case, it would be helpful to return a message that says something like “The requested resource could not be found. Please check the URL and try again.”
By handling errors gracefully, you can improve the user experience for those who are interacting with your REST API.