The API guide
What is a headless API?
David Fateh
Updated: January 15, 2025
The API guide
This is chapter 5 of the series, The API guide
Summary
A headless API (application programming interface) provides a back end to your apps and websites without making assumptions about how the data or functionality it provides is going to be used.
Headless APIs are commonly provided by content management systems (CMSes), ecommerce and payment platforms, and email and communication providers. Developers that leverage headless APIs can reduce or eliminate the amount of backend code they need to write to achieve the functionality they require for their projects.
This chapter explains headless APIs, what separates them from traditional APIs, and their benefits to developers. It discusses the advantages of using off-the-shelf APIs in your development process and provides a list of headless APIs that provide different services for blogs, online stores, communication, and other use cases.
What is a headless API?
Headless APIs serve the same purpose as any API: allowing applications to communicate by providing programmatic access to data and functionality. APIs allow software to communicate using a standard set of commands and syntax established by the API creator, so that applications don't have to be directly integrated with each other.
APIs are commonly provided online using the HTTP protocol and GraphQL or REST, each with their own advantages depending on your project, or they can communicate locally using interprocess communication (IPC) or through the host operating system.
In software development, "headless" refers to an application or system without a graphical user interface (GUI). APIs by definition do not include a GUI for displaying and interacting with the application (known as the "head" because it communicates with users), and only provide the data and processing functionality (the "body" that does the work). This technically makes every API "headless," but the term "headless API" reinforces the distinction between APIs in general and ones designed without a specific front end in mind.
Difference between headless APIs and traditional APIs
Traditionally, APIs were developed for in-house projects where the front end and back end were designed in tandem and would include considerations for each other (for example, a special API endpoint might be created to handle an edge case for a specific frontend implementation). They were tightly coupled, as the teams working on the API and the apps that would use it were usually part of the same team or organization and didn't have to consider other use cases.
Headless APIs are completely decoupled from the applications that connect to them. With the emergence of software as a service (SaaS) platforms that provide the functionality that developers would previously have had to write themselves, APIs have become more standardized so that they can target a broad range of scenarios.
Headless API architecture
In some cases, you will build your own API to connect your backend applications and databases with your frontend websites and apps, but it is becoming increasingly common in web development to eschew developing, testing, and maintaining your own backend code and API and instead leveraging third-party back ends that provide all of the functionality, security, and APIs that you need to provide functionality to your bespoke frontend apps.
Headless APIs assist this by making fewer assumptions about how they are used and trying to remain independent of the frontend language, deployment environment, or end purpose. Rather than trying to do everything, headless APIs provided by online platforms usually focus on one specific task, for example, providing a CMS that delivers text and media, or providing users the ability to make secure online payments.
This allows developers to mix and match products that provide APIs that achieve the backend functionality they require without having to write the code themselves. As an example, below is an architecture for a simple app that uses a headless CMS API to retrieve product details and an online payment API to take payment from a customer:
The CMS and Payments APIs are unaware of each other (or what the front end looks like), each performing their specific task independently. This is an example of a composable architecture.
If you are developing your own headless API (either for public consumption or to support your internal applications), it can be delivered by a microservices-based architecture, but this is not a requirement.
Benefits of decoupling front and back ends
The decoupling of front and back ends provides the following advantages to developers:
Focus on the user experience
Developers are freed from writing backend code and can focus on improving the front end and the aspects of the application that engage users.
Scalability and performance
SaaS providers operate at scale, so using their functionality to power your apps via headless APIs means you don't have to worry about scaling your own infrastructure to meet fluctuating demand.
Security
Online services that target an international audience will take care of the security of their own platforms and ensure that they are compliant with the wide array of privacy and data protection regulations required by different countries, reducing your security responsibilities.
Omnichannel delivery
You can connect both your native mobile and desktop apps as well as your websites to the same headless APIs.
Integration of multiple platforms
Combine independent headless APIs in your front end without having to worry about whether they were designed to work with each other.
Use any library or framework
JavaScript, Python, or Ruby? React, Angular, or Laravel? Mobile or desktop apps? You can connect to a headless API from any language, framework, or platform.
There are also advantages for businesses who decide to use headless APIs in their applications:
Cost
Outsourcing functionality to platforms that provide APIs you can integrate into your own code means you don't have to pay to develop and maintain backend code or to host it.
Time to market/MVP
Reduced development time means your product gets to your audience faster, and you can focus on updating it based on feedback to increase user engagement.
Manageability
Separation of concerns means that tools are developed to be the best at their specific purpose, letting content teams use platforms that are tailored for creation, analytics teams use best-in-class analysis tools, etc.
Future proofing/flexibility
By decoupling the components of your applications, you can always swap out a particular service if it stops meeting your requirements rather than throwing everything away.
Brand consistency
Headless APIs mean you are in full control of your front end and can make sure it truly reflects your brand rather than having to adapt your aspirations to fit with pre-built frontend templates provided by more tightly coupled platforms.
Headless API: Build or buy for your use case?
During the planning stages of your project, you'll face the decision on whether to build your own APIs and back end, or buy off-the-shelf solutions. This decision factors:
Whether or not it is a public-facing website or application
Customers expect fast, responsive applications, but businesses may sacrifice usability and reliability to reduce costs and throw something together in-house.
The nature of the application
Does the application follow established paradigms that can be met by existing products (for example, online stores all provide similar, standardized functionality), or do you need highly customized behavior (for example, integration with legacy tools or industry-specific workflows)?
Longevity and vendor lock-in
Is this a throwaway application for a single short-term purpose, or do you plan on maintaining and hosting it for the long term? Does the cost of developing and maintaining code yourself outweigh the cost of a third-party headless API?
Data ownership and security
Does your data need to stay on your infrastructure for security or privacy reasons?
The answers to these questions will change with the technology available: Not long ago, data ownership and the need for bespoke back ends for specific purposes ruled out most SaaS products.
However, headless architectures backed by API platforms that focus on security and composability now let you assemble back ends using tools that don't lock you into their way of doing things, so that you maintain control of the end result without having to build anything yourself.
How to implement a headless API
Below is a list of the most popular headless APIs for common use cases provided by online SaaS platforms:
Headless APIs for online payments
SaaS Product | Purpose |
---|---|
Stripe | A developer-first headless API for online payments, subscriptions, and invoicing. |
PayPal | An online and mobile secure payment processing system with an API. |
Square | APIs for online payments as well as integration with in-person payment devices. |
Headless APIs for ecommerce
SaaS Product | Purpose |
---|---|
Shopify | An ecommerce platform that provides an API for implementing your own storefronts. |
BigCommerce | A developer-focused headless ecommerce API that lets you build your own front end. |
CommerceTools | A composable commerce platform that provides an agnostic back end for making purchases. |
Headless APIs for authentication
Saas Product | Purpose |
---|---|
Auth0 | A headless authentication API that provides secure authentication for your apps, including support for signing in with Google, Microsoft, and other accounts. |
Okta | An identity management API for business use cases. |
Google Firebase Authentication | An authentication system for mobile and web apps that use Google services as a back end. |
Headless APIs for communication
Saas Product | Purpose |
---|---|
Mailgun | An email provider for sending transactional emails programmatically using a headless API. |
Twilio | A communication platform with support for SMS, voice, and push notifications. |
Vonage | A voice communication service for making phone calls, reading transcripts, and sending messages using a headless API. |
Headless APIs for analytics
Sass Product | Purpose |
---|---|
Google Analytics | A popular data analytics platform that can collect usage data from apps and websites using an API. |
MixPanel | A behavioral analytics API. |
Amplitude | An analytics tool that can be integrated with your products, with a headless API for collecting and accessing usage data. |
Other headless APIs for interactive apps
Saas Product | Purpose |
---|---|
Algolia | An API for implementing search for websites and applications. |
Google Maps API | A headless API for geolocation, retrieving map data, and providing travel directions. |
Mux | A headless API for video live streaming across different platforms. |
Building your own headless API
Building your own headless API requires development experience, as you'll need to write your own backend code to read and write data to your database, as well as perform calculations and other functions that can be exposed for use by your front end.
While planning and developing your API, you will need to deliberately avoid making assumptions about how it will be used, use a standard API technology like REST or GraphQL, and use authentication like OAuth 2.0 so that any front end can connect to it.
When connecting your front end to any API, you should consider implementing caching and other optimization techniques. This will ensure that your user experience is fast and responsive by reducing the amount of network traffic your application needs (especially useful if your audience primarily uses mobile devices), and reduce the load on your infrastructure (and the subsequent bills).
Contentful is a composable back end for your websites and mobile apps
Contentful is more than just a headless API for content management.
The Contentful Composable Content Platform lets you define exactly what data you need for all of your frontend applications and websites, all managed from a central web interface that lets your content creators live-preview all the text, video, audio, and other content in all your applications just as they appear to your users.
Once you've connected your front ends using our REST and GraphQL headless APIs, your content is delivered to them using our high-speed global delivery network with servers located right where your users are, so your apps and websites load quickly.
Build your apps your way, without writing backend code or maintaining any infrastructure.
Unlock the power of your digital content
This is the last chapter of our API guide, but it’s just the start of unlocking the full potential of APIs for your projects.
Explore how our tools and expertise can help you design, manage, and optimize APIs for any challenge. Chat with our team today.
Written by
David Fateh
David Fateh is a software engineer with a penchant for web development. He helped build the Contentful App Framework and now works with developers that want to take advantage of it.