REST API Best Practices and Standards in 2024

Mastering the REST API Best Practices is an art! APIs are used by every software professionals, but not everybody can write the best ones. The security concerns of people because of the poorly written APIs need attention. When you are designing REST APIs, these REST API Best Practices will help you to elevate your API writing skills. As a REST API designer, writing an effective API will make your work easier.

In this blog, you will be introduced to REST API along with REST API standards. The working and characteristics of REST API are elaborated. Ten REST API Best Practices with examples will be discussed.

What is REST API?

REST API is like a set of rules for different programs to talk to each other. It is an application programming interface that follows specific guidelines for this. There are numerous communication protocols to access REST APIs, but HTTPS is the most common. Each interaction of REST API is independent of past communications and information is stored temporarily in it to enable faster functioning. 

REST API standards

The API best practices and standards are a must-follow for all the REST APIs. The REST API standards have a list of constraints to abide by. These REST API guidelines and constraints are explained below.

1) Statelessness

Systems aligning with the REST paradigm are bound to become stateless. For Client-Server communication, stateless constraint enforces servers to remain unaware of the client state and vice-versa. A constraint is applied by using resources instead of commands, and they are nouns of the web that describe any object, document, or thing to store/send to other resources.

2) Cacheable

Cache helps servers to mitigate some constraints of statelessness. It is a critical factor that has improved the performance of modern web applications. Caching not only enhances the performance on the client-side but also scales significant results on the server-side. A well-established cache mechanism would drastically reduce the average response time of your server.

3) Decoupled

REST is a distributed approach, where client and server applications are decoupled from each other. Irrespective of where the requests are initiated, the only information the client application knows is the Uniform Resource Identifier (URI) of the requested resource. A server application should pass requested data via HTTP but should not try modifying the client application.

4) Layered System

A Layered system makes a REST architecture scalable. With RESTful architecture, Client and Server applications are decoupled, so the calls and responses of REST APIs go through different layers. As REST API is layered, it should be designed such that neither Client nor Server identifies its communication with end applications or an intermediary.

5) Client-Server

The client and server applications must be able to function without the help of each other. Both the server application and the client application must abide by the separation of concerns agreement. By this agreement, when altering the client end, there should not be any impact on the server application. And also, when the code of the server is altered, it should not affect the client end. This enhances the scalability and flexibility of the interface across platforms.

6) Code on demand (optional)

Of all the constraints, this one is optional. The usual format used while sending resources is JSON REST API or XML. But whenever it is required, you are provided with an option to return executable code. This will support the main part of your application.

Working of REST API

A REST API requires a host URL that acts as the primary address for your interactions. REST APIs also need a set of endpoints, which are unique addresses within-host URLs responsible for its functionality. Moreover, it is a good practice to document the endpoints, return value, data types, and other essentials of a REST API. 

The below diagram is a high-level representation of the required organization of your code to create a REST API. You may have one or more databases that contain data that other applications might need. So, they will use the REST API that uses SQL and JDBC to interact with the database. REST APIs enable you to centralize all your basic logic in one place instead of rewriting it every time you want to create a new app as shown by the below image. 

Now, APIs are designed to return the required data whenever a user calls them. However, when you use REST APIS, it not only returns the requested data but also presents it in a well-structured form for representation. A REST API utilizes a client-server architecture that allows different applications to communicate. The client software makes a call to the server application using a REST API. The Server application sends the requested data in a structured form organized using key parameters over the HTTP protocol.

Characteristics of a Well-designed API

• Flexible: REST API is flexible with multiple types of calls like returning different data formats and changing structurally with the correct implementation of hypermedia. It allows users to communicate back and forth with clients and servers, even if they are hosted on different servers.
• Adaptable: REST API is adaptable to any modification done in data that resides in the database, even when hosted on the different back- and front-end servers. Since it depends to a certain extent on codes, it helps synchronize data within websites without any issue.
• Ease of Understanding: As REST uses HTTP verbs (GET, POST, PUT or DELETE) methods for communication, these methods are self-explanatory. In addition, REST architecture helps increase developers’ productivity, allowing them to display the information on the client-side and store or manipulate the data on the server-side.
• Easy to Read and Work: A well-designed API will be simple to use, and developers who use it frequently will quickly remember its resources and associated activities.
• Hard to Misuse: Developing and integrating with a well-designed API will be an easier process, with the reduced likelihood of creating incorrect code. It provides helpful feedback and does not impose tight guidelines on the API’s end users.
• Complete and Concise: A robust API will enable developers to create full-fledged applications using the data you disclose. Completeness typically occurs over time, and most API designers and developers build progressively on top of the existing APIs. It is an ideal that every engineer or organization using an API should aim for.

REST API Best Practices

While designing REST APIs, you need to focus on all these best practices to make your REST API the best. As a REST API designer, you must focus on the safety as well as the working of the API.

REST API Best Practices: Prioritize Nouns over Verbs in URI

Since REST API is mostly developed for resources like services, it is essential to use Nouns and not verbs. So it is better to use only Nouns to represent an entity in REST endpoint paths. This is because the HTTP request method already consists of verbs. So having verb in REST API endpoints will not pull any new information. You must use tags to change the resource’s state.

The following table helps you in understanding the REST API Verbs:

REST Verb	Action
GET	Fetches a record or set of resources from the server
OPTIONS	Fetches all available REST operations
POST	Creates a new set of resources or a resource
PUT	Updates or replaces the given record
PATCH	Modifies the given record
DELETE	Deletes the given resource

Here are a few examples to show how the endpoints should look like,

• GET/books/123
• DELETE/ books/123
• POST/books
• PUT/books/123
• PATCH/book/123

Consider a code where we are using the Express to add the above-mentioned endpoints for manipulating articles. You can see that only nouns are used here, and there is no verb. 

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REST API Best Practices: Prefer using Plural naming conventions

Generally, it is the best practice to use plural nouns for collections. This plural naming convention becomes a global code. This also helps normal people to understand that these groups of APIs form a collection.

The following table helps you in understanding the right and wrong usage of plural names in REST API :

Do’s	Dont’s
GET/bikes/123	GET/bike/123
POST/bikes	POST/bike
GET/bikes	GET/bike

REST API Best Practices: Utilize Resource Nesting Efficiently

Resource nesting is a practice of clubbing two functions that have some hierarchy or are linked to each other. Nesting to one level is one of the best practices to group resources that are logically coherent. For example, ‘order‘ and ‘users‘ are two resources of the same category in an online shop. The ‘user’ makes the ‘order’ and the ‘order’ belongs to the ‘user’. The following code explains the scenario discussed above.

/users // list all users
/users/123 // specific user
/users/123/orders //list of orders that belong to a specific user
/users/123/orders/0001 // specific orders of a specific users order list

Overusing Nesting is not good in any case. When overused, Nesting loses its appeal and creates unwanted dependency issues. So the REST API best practice that can be followed is limiting the use of nesting to one level.

REST API Best Practices: Systematic Documentation

Another important REST API best practice is to document all the solutions in a very systematic manner. The utilization of framework, application, or software usage requires proper documentation. This document will act as a reference while troubleshooting an issue. This API documentation needs to be precise and simple enough for non-technical people to understand it. Doing such systematic documentation will help your users indulge and understand all the necessary aspects like error handling, security, and authentication.

REST API Best Practices: Data Filtering options

When the database grows, it becomes a great challenge to manage it. The main challenge in this huge database is to retrieve only the requested data. The entire database should not be exposed while retrieving data. For fulfilling this, you need to use a filter that will pull data that satisfies the required criteria. By filtering the data while retrieving, huge bandwidth is saved in the client’s end. REST API provides you with 4 types of filtering options. The REST API filtering options include:

• Filtering
• Sorting
• Paging
• Field Selection

Filtering

Using this you can filter results that satisfy your required conditions. You can use search parameters like country, creation, date and etc for this.

ET /users?country=UK
GET /users?creation_date=2021-10-11
GET /users?creation_date=2021-10-11

Sorting

You can sort your results in ascending and descending order using this option.

GET /users?sort=birthdate_date:asc
GET /users?sort=birthdate_date:desc

Paging

Using the ‘limit‘ option, you can narrow down the results to the required number. You can also use ‘offset‘ to show the part of the overall results displayed.

GET /users?limit=120
GET /users?offset=3

Field Selection

Using the field selection function, you can request to display a specific part of the data available for that object. While you query an object with many fields, you can specify the fields in your response. An object will have ‘Name’, ‘Surname’, ‘Birthdate’, ‘Email’, ‘Phone’ as its fields.

For example, when you want to retrieve the birthdate and email to automate birthday wishes. You can use a query like this:

For a specific user:

GET/  users/123?fields=name,birthdate,email

For a full list of users:

 GET/ users?fields=name,birthdate,email

REST API Best Practices: Utilize SSL/TLS security layers

One of the REST API Best practices is to encrypt the communication using SSL/TLS. It is very essential to ensure database security for any API developer. The earned trust of the customers to keep their sensitive details private is a must. To avoid security breaches, you need to use SSL (Secure Socket Layer) and TLS (Transport Layer Security). SSL/TSL provides a public and private key to give a secured connection. TSL is an advanced version of SSL and hence provides better protection and security.

REST API Best Practices: Focus on Error Handling

Handling error with care is one essential skill of an API developer. The HTTP error code will point to the nature of the individual error when the API is effective. REST API has 71 unique errors with HTTP status codes with error messages. Along with the standard error handling of HTTP statuses, and elaborated message on the internal code will help the user to understand better.

Idel error handling code consists of 3 parts:

• Error – a unique identifier of the error
• Message – a comprehensive, readable message
• Detail – lengthier explanation of the message

Common error HTTP status codes consist of:

• 400 Bad Request – This shows that validation of client-side input has failed.
• 401 Unauthorized – This returns when the user isn’t authenticated.
• 403 Forbidden – This indicates that the user is authenticated but cannot access a resource.
• 404 Not Found – This implies that a resource is not found.
• 500 Internal server error – This is a generic server error and should probably not be thrown explicitly.
• 502 Bad Gateway – This indicates an upstream server’s invalid response 
• 503 Service Unavailable – This indicates that something unexpected happened on the server side, such as server overload or failure of some parts of the system.

For example, when you receive a login response with an incorrect password, you can send a 401 response with a code like this,

{ "error": "auth-0001", "message": "Incorrect username and password", "detail": "Ensure that the username and password included in the request are correct" }

Even while some people believe REST should only return hypertext (including Roy Fielding, the term’s creator), REST APIs should accept JSON as a request payload and deliver responses in JSON. JSON is the standard for data transmission. It can be used with almost any networked technology. JavaScript includes built-in methods for encoding and decoding JSON using the Fetch API or another HTTP client. Server-side technologies include libraries that can decode JSON without much effort.

There are different methods for transferring data. XML is not widely supported by frameworks until we change the data into something usable, which is typically JSON. We can’t alter this data as readily on the client side, particularly in browsers. It ends up being a lot of extra labour just to transfer regular data.

Form data is useful for transferring data, notably files. However, we do not require form data to transfer text and numbers because most frameworks allow us to transport JSON by simply retrieving the data from it on the client side. It’s by far the easiest way to do so.

To ensure that clients interpret our REST API app’s responses as JSON, we should set the Content-Type in the response header to application/json once the request is made. Many server-side app frameworks configure the response header automatically. Some HTTP clients examine the Content-Type response header and parse the payload using that format.

The only exception is when we attempt to send and receive files between the client and the server. Then, we have to handle file replies and deliver form data from the client to the server. But that is a subject for another time.

We should also ensure that the endpoints return JSON as their response. Many server-side frameworks include this as a standard feature.

Let us check out an example API that inputs JSON payloads. This example will make use of the Express backend framework for Node.js. We may use the body-parser middleware to parse the JSON request body and use the res.json method with the object that we wish to return as the JSON response, as shown below:

const express = require('express');
const bodyParser = require('body-parser');

const app = express();

app.use(bodyParser.json());

app.post('/', (req, res) => {
  res.json(req.body);
});

app.listen(3000, () => console.log('server started'));

bodyParser.json() interprets the JSON request body string into a JavaScript object, which is subsequently assigned to the req.body object.

Change the Content-Type header in response to application/json; charset=utf-8 with no modifications. The solution described above is applicable to the majority of different back-end frameworks.

REST API Best Practices: Versioning your APIs

You should always have multiple versions of API if you’re making any changes that might break clients. The versioning can be done per the semantic version (for instance, 2.0.6 refers to major version 2 and the sixth patch) like most applications do nowadays.

This way, you can cautiously remove old endpoints rather than forcing everyone to update to the new API. You can keep the v1 endpoint active for those who don’t want to change and use v2 for those who are ready to upgrade. This is essential for public APIs. 

You can do versioning by adding /v1/, /v2/, etc., at the start of your API path.

For instance, we can do that with Express as mentioned below:

const express = require('express');
const bodyParser = require('body-parser');
const app = express();
app.use(bodyParser.json());
app.get('/v1/employees', (req, res) => {
  const employees = [];
  // code to get employees
  res.json(employees);
});
app.get('/v2/employees', (req, res) => {
  const employees = [];
  // different code to get employees
  res.json(employees);
});
app.listen(3000, () => console.log('server started'));

You can add a version number at the start of the endpoint URL path to version it.

REST API Best Practices: Always choose JSON

JavaScript Object Notation is one of the easiest languages and an easy-to-use format. One of the important best practices to follow is to always choose JSON. The key feature of JSON is that it is very easy to parse and supports most frameworks. JSON can be used by any programming language.

Consider an example of an API accepting JSON payload. Express back-end framework is used here for Node.js. To parse the JSON request body, you can use body-parser middleware. You can then call res.json method with the object you want to return as a JSON response. 

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The JSON request body string is parsed into a JavaScript object by bodyParser.json(). It is then assigned to the req.body object. 

REST API Best Practices: Improve Performance by Caching Data

You can add caching in order to return data to local memory. This can save you from querying the database everytime while retrieving data as requested by a user. Even though it helps you to get data faster, the data obtained can be outdated, which can lead to issues while debugging. You can change the way in which data is cached as per your needs. 

Apicache middleware of Express can add cache to your app without the need of much configuration. This can be done as follows:

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You should include Cache-Control information in your headers while caching. By using this, users will be able to use your caching system effectively. 

REST API Best Practices: Manage REST API Requests and Responses Effectively

Manage your API requests and responses effectively after designing your endpoints. This is essential for a secure user experience and seamless communication between client and server.

You should use appropriate status codes in your responses. For all successful requests, use  200. Use 500 for server-side errors, and for client-based errors, use 400. Regularly monitoring your API’s usage and activities can be extremely helpful in identifying common errors and any downtimes associated with your API. Handle network timeouts, set reasonable timeout limits, and provide useful feedback for timeouts to the clients.

REST API Best Practices: Use the Appropriate Request Headers for Authentication

To pass authentication information from the client to the server, use Request headers. You can implement authentication mechanisms like API keys, OAuth, JWT (JSON Web Tokens) or other custom authentication schemes for this. Below are some recommended request headers you can use:

Authorization header: It enables the client to include authentication credentials, such as tokens or API keys, in the request header. Consider an example of using the Bearer scheme for sending JWT authentication credentials after the scheme. 

Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

API key header: You can also use an x-api-key header to authenticate API requests.  In this header, the client needs to include an API key, and a unique identifier. the API key value on the header is sent to the client for authentication.

x-api-key: ABCDEFG123456789

Custom headers: These can pass authentication-related information depending on the authentication mechanism. 

X-Auth-Token: abcd1234

REST API Best Practices: Know When to use Parameters vs. Query Parameters

You need to understand when you have to use path parameters (e.g., /api/books/{id}) and when to use query parameters (e.g., /api/books?category=fiction). This is essential when additional information is passed in the endpoint from the client. 

You can use Path parameters to identify or retrieve a specific resource. Query parameters are better suited for sorting the request data. They can also be used for filtering and pagination.

In the example of books API, we’ve used path parameters for deleting a book or updating a book information using the endpoint /api/books/{id}. Here, the path parameter is id with a unique book identifier as its value.  For example,  to retrieve all the books of a certain category, you can use query parameters.  It is as follows- /api/books?category=fiction. In this, the query parameter is a category having fiction as its value. 

REST API Best Practices: Version your REST APIs

You should also version your APIs to easily manage changes and updates to an API. You can assign unique identifiers or labels for this. Following are some common approaches to versioning your API:

URL versioning: the API version is included in the URL here. For example, /api/v1/books show that this is version 1 of the API.

Query parameter versioning: It specifies the version number in the API request as a query parameter. For example, /api/books?version=1.

Header versioning: The custom header consists of the version number in the API request. For example, Accept-Version: 1.

Content negotiation versioning: On the basis of the Accept header or the media type of the request payload, the version is negotiated.  

REST API Best Practices: Performance Optimization Techniques

Performance is important to know the end-user experience of your APIs.

To create high-performing REST APIs, you can use the following optimization practices: 

• You should store frequently accessed data and reduce the load on the server using caching mechanisms. This helps to reduce network traffic and improve response times while sending data between client and server.
• Implement pagination for retrieving large datasets in smaller, more manageable chunks to ensure an optimized API design. This helps APIs efficiently handle large amounts of data.
• You can reduce the size of data transferred between the client and server by using compression techniques, such as gzip. This enables improving response times for bandwidth-constrained environments.
• To control the number of requests of a particular client within a particular timeframe, you can use rate limiting and throttling mechanisms.  Through this, you can ensure better usage of your REST API resources. 

REST API Best Practices: Apply These Security Best Practices

Security is a critical but also a tricky subject. you can protect your APIs and sensitive data by resolving some issues with it. 

Some of the security best practices you can add to your REST APIs:

• You should validate and sanitize user inputs properly on the server side. To prevent malicious code execution, it is good to encode the API response. Your REST APIs will be protected against vulnerabilities like SQL injection and cross-site scripting (XSS).
• Foolproof authentication and RBAC (Role-Based Access Control) mechanisms are essential for preventing your database resources from being accessed by unauthorized users. Ensure that all of your data is only accessed by users allowed by you.
• You can use tools like Edge Stack to enable traffic encryption and common attacks like DDoS.

SQL Server REST API Integration simplifies data movement and boosts its capabilities, making SQL Server a dynamic hub for real-time data updates and interactions, thus improving overall functionality.

REST API Best Practices: Give feedback to help developers succeed

Feedback to developers is critical for the improvement of the product. Good feedback should also include an indication of incorrect implementation. This can help users debug and correct the way of using the product. You should use the standard HTTP codes. Client-side calls should consist of  400-type errors and 500-type errors for any server-side errors. When using your API, there can be three possible outcomes:

• An erroneous client application (client error – 4xx response code)
• Error in API functioning (server error – 5xx response code)
• The client and API successfully worked (success – 2xx response code)     

Resolving issues when any dead-end arise for your consumers can help you with your API in improving the developer experience and preventing API misuse. 

REST API Best Practices: Consistency is the key

 You should use consistent naming and URI conventions to avoid confusion and better functionality. 

• For hierarchical relationships, use forward slash /

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• Avoid using trailing forward slash (/) in URIs

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• improve the readability of URIs using hyphens (-)

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• Avoid underscores(_)

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• In URIs, use lowercases 

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REST API Best Practices: Do not use file extensions

File extensions are not of much use and not using them decreases the length of URIs. So avoid them. 

If you want to use file extension for highlighting the media type of API, use media type.  For instance, the Content-Type header tells how to process the body’s content.

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Conclusion

From this blog, you would have learnt about REST API along with REST API standards. The working and characteristics of REST API will be clear to you now. Ten REST API Best Practices with examples are all yours. What are you waiting for! Use them and master this ART. Hevo’s native REST API connector can help connect with a variety of non-native/custom sources into your Data Warehouse to be visualized in a BI tool.

Hevo is the only real-time ELT No-code Data Pipeline platform that cost-effectively automates data pipelines that are flexible to your needs. Hevo provides a pre-built Native REST API Connector that will allow you to integrate data from a plethora of custom and non-native sources.

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Share your understandings on the topic of REST API Best Practices. Tell us in the comments below!

References:

• JSON return response example
• API Versioning Example