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Best Free API Documentation Tools

As data science and predictive analytic become more widely used, the need for clean and reliable APIs is becoming increasingly important. Documentation is a key indicator of an API’s quality, so finding the best free documentation tools to help you create mockups and powerful landing pages becomes essential.

API documentation is human and machine-readable technical content that explains how a specific API works and what it is able to do. Its purpose is twofold. Firstly, it is an accurate reference source that describes the API in detail. Secondly, it can act as a guide and teaching tool that helps users get started and use it. 

Done correctly, API documentation acts as the one true source of information for how an API works. It should contain details on functions, arguments, classes, and more in a structured format that is easy for both developers and non-technical users to understand. Often, it will include tutorials and examples, which will help the user better understand how the different parts work together.

API documentation refers to the collection of tools, processes and guides used to describe an API in a manner that allows users and developers to understand what it does, how it works and where you can use it in your application. Below are some of the best FREE API documentation tools. It won’t cost you a dime.


Investing time and resources into creating high quality API documentation leads to many benefits:

  • Reduced Onboarding Time – Customers and internal users can access the information they need to start using and benefiting from your API immediately. 
  • Reduced Reliance on Support – Good documentation reduces the strain on your API experts and helps other users find their own answers. This applies regardless of whether your API is internal-only or used by thousands of customers,
  • Encourage Non-Engineering Users – By increasing the understanding of non-coding colleagues, your API documentation enables better discussions around how your APIs and data can be used to achieve your business goals.
  • Increased Adoption Rate – Easy-to-use API documentation will increase the rate with which new users can start using your API. By providing a better user experience, businesses will benefit from increased word-of-mouth marketing, which leads to faster adoption.
  • Improved User Satisfaction – Happy customers and colleagues improve your business’s reputation.

Are you struggling to create and manage your APIs effectively? The DreamFactory Platform enables businesses to automatically generate enterprise-grade APIs (and their documentation) without any coding necessary. Start your free 14-day hosted trial today.

What Makes a Great API Documentation?

Creating great API documentation is a delicate balancing act between providing detailed technical information and displaying it in a way that is easy to consume. The best way to see how it should be done is to look at examples of businesses that are doing well – thankfully, they’re not hard to find. 

Many popular tools publish their API documentation online so that 3rd-party developers can get easy access to them. Stripe and Twilio are two great examples of documentation done right. Although their solutions are developed in-house, the best practice they display is still useful for businesses looking to create their own API documentation. Here are a few of the reasons why these sets of documentation are so effective:

  • They provide example code in the documentation so that users can see how it works in practice.
  • They make it easy to find solutions to common problems so that busy developers can get what they need quickly.
  • They don’t provide unnecessary information that isn’t required to understand the API and how it works. When users are busy working and hit a problem, they want usable documentation, not extraneous information.
  • They don’t assume a certain level of knowledge – the simplest concepts are as fully-explained as the most difficult ones.
  • They are well-formatted. The content is organized and consistent and easy to read. This reduces friction for users who are looking to learn or solve a problem.

Which Specification is Best?

There is more than one way to write API documentation, and different software uses different specifications. These specifications each provide a different standard and style in which an API is described. Three of the most popular are:

  • OpenAPI (formerly Swagger) – The most popular specification. Open-source, and backed by companies such as Microsoft and Google. Uses JSON objects with a specific schema to describe API elements.
  • RAML – YAML-based, RAML (or RESTful API Modeling Language) takes a top-down approach to create documentation that is clear, consistent, and precise.
  • API Blueprint – Another open-source specification, API Blueprint is designed to be highly accessible. It uses a description language that is similar to Markdown and excels in situations where a design-first philosophy is followed during API creation.

While all of these options work well, it is the OpenAPI format that has achieved the most momentum in the last few years. With big brands behind it, it has quickly grown a large community and subsequently has the largest range of tools available. This makes it a good choice for businesses who aren’t sure which specification to go with because there’s a broader choice and a better chance of getting community support if you get stuck.

5 Best API Documentation Tools

There’s no shortage of API documentation tools on the market. The following five are our pick of the best options:

Swagger UI

Swagger UI is a popular tool for creating interactive API documentation. Users input an OpenAPI Specification (OAS) document, and Swagger UI formats it using HTML, JavaScript, and CSS to create great looking documentation.

Swagger UI is part of the Swagger ecosystem, which includes a wide range of tools, many of which are open-source (including Swagger UI), as well as a premium version (SwaggerHub – see later). 

It’s benefits include:

  • Fully customizable – Users have access to the full source code and can tweak Swagger UI to suit their use, or take advantage of the tweaks made by other users.
  • Supports OAS 3.0 – Works with OpenAPI Specification Version 3.0, as well as the older Swagger 2.0
  • Very popular – It’s easy to get support from other users if you run into problems.

Swagger also offers other open-source tools that complement Swagger UI by helping create the OpenAPI Specification (OAS) document that it uses. Swagger Editor enables users to create their own OAS definition which they can then visualize with Swagger UI, while Swagger Inspector enables users to auto-generate OAS definitions from an API endpoint.


Swagger UI Website

Swagger Petstore Demo


SwaggerHub is a premium platform that combines features from Swagger UI, Swagger Editor, and many other parts of the Swagger ecosystem. It is aimed at business and enterprise users and contains many additional features that are designed to optimize the documentation workflow.

It’s benefits include:

  • One package – Unlike Swagger UI, SwaggerHub offers a complete API documentation toolset without the need to find additional software.
  • Automatically generate documentation – SwaggerHub enables users to automatically generate interactive API documentation during design.
  • Improved collaboration tools – Permissions & user roles, real-time commenting, issue tracking, and team management tools.

Unlike Swagger UI and many of the other options on this list, SwaggerHub is a paid solution. However, for larger businesses with a heavy reliance on APIs, this may be a worthwhile investment.


SwaggerHub Website

DreamFactory is a REST API management platform. In addition to providing all the tools businesses need to create and manage multiple REST APIs, DreamFactory will also automatically create Swagger documentation for every API it generates. Start your trial today or contact the team for more information.


ReDoc is a free and open-source documentation tool that supports OAS 2.0 and OAS 3.0. Using ReDoc, businesses can quickly publish great-looking interactive API documentation online.

Benefits include:

  • Flexible – ReDoc can run in your browser, but it’s also available as a Docker image, as a React component, or as a command-line tool.
  • Stylish & responsive – The good-looking theme is fully-responsive, and it will work well on any screen size or browser. Additionally, you can customize fonts, change colors, and easily add a logo.
  • Easy navigation – The customizable navigation bar and search box enable users to quickly find the information they need.


ReDoc Website

ReDoc on GitHub

ReDoc Live PetStore Demo 


DapperDox is an open-source OpenAPI renderer that works with both OAS 2.0 and OAS 3.0.

Benefits include:

  • Integrate Markdown content –  DapperDox enables users to combine their OpenAPI Specification with diagrams created using GFM (GitHub Flavored Markdown).
  • Good documentation – The DapperDox documentation is clearly-written and helpful for new users.
  • API explorer – DapperDox’s API explorer enables users to experiment from within the API documentation.


DapperDox Website

DapperDox on GitHub

OpenAPI Generator

OpenAPI Generator is an easy-to-use tool for generating documentation for OAS 2.0 and OAS 3.0 documents, as well as server stubs and libraries. It is known for being relatively simple and easy to use (without sacrificing power) and for being highly extensible (for example, it supports more than 50 client generators)

Benefits include:

  • Community support – OpenAPI Generator has a large community of experienced users that discuss and use it and that can be a valuable resource when creating documentation.
  • Server stubs – OpenAPI Generator enables users to create server stubs for more than 40 different languages, including PHP, Java, and GO.
  • Documentation formats – Convert OAS documents into HTML or Cwiki formats


OpenAPI Generator Website

OpenAPI Generator on GitHub

Generate a full-featured,documented, and secure REST API in minutes.

Sign up for our free 14 day hosted trial to learn how. Generate your No Code REST API now

Manage APIs Better With DreamFactory

Need another option? You might want to consider DreamFactory:

DreamFactory uses Swagger to generate live API documentation for every single API you create. Using DreamFactory for your API docs has several benefits:

  • Automatic – Your team can have confidence that your documentation is up-to-date and correct at all times. No need to wait for a busy developer to update your documentation.
  • Importing – Working with 3rd Party APIs? No problem. You can import their OAS documents into DreamFactory so that your users can access and view them as if they were your own.
  • Administrative Privileges – DreamFactory prevents your documentation by ensuring that only developers with DreamFactory admin privileges can modify them. Other users can only view it.
  • Fully Interactive – Your team can access a live and interactive document within seconds of launching an API.

Documentation is just one of many enterprise-grade features that makes DreamFactory the ultimate API-as-a-Service platform. With DreamFactory, it is easy to create, manage, and document tens or even hundreds of REST APIs. 

DreamFactory enables businesses to create professional fully-featured REST APIs in seconds, is highly secure, and enables central management of every API from one platform.

Announcing the Launch!

Since its conception, DreamFactory has consistently provided value to its customers with its on demand, custom generated API management tools, and we’re proud of how we’ve been able to support our customers. As a result of our continued growth we have made the decision to enter into a strategic merger with some of our Xenon Partners sister companies to form launched on December 15, 2021, bringing together four companies (Xplenty, DreamFactory, FlyData and to provide a complete data integration platform. is a data warehouse integration platform designed for e-commerce. The platform allows your organization to integrate, process, and prepare data for analytics on the cloud. Because it is a code and jargon free environment, the platform allows your business to take advantage of the opportunities offered by big data without having to invest in hardware, software, or related infrastructure. 


Redocly sits comfortably at the top of this list because it supports OpenAPI v2 and Open API v3. It is also very flexible and highly customizable. Regardless of the activated mode, each end-user has full control over its responsiveness on mobile, color themes, fonts, and branding images.

The interface is clean and non-cluttered. The platform has been designed to focus on simplicity and functionality, which should be attractive to its users to use it regularly without feeling overwhelmed or intimidated by too many features.

Redocly API Documentation Tool

Users can also use a wide range of extensions with this API documentation tool. This includes project logo URL, links to code samples, and integration with a Github repository.

The API documentation tool, which is based on React JS, has both free and paid versions. It also has incorporated in it a CLI that gives you access to all Open API definitions.

Although originally designed for large enterprises, it can also be used by individuals and small teams. In general, the pros of are;


  • Highly customizable
  • Packed with a lot of power
  • Easy to deploy and use
  • Has a gallery of rich and detailed document templates


Like every other platform, it has its own fair share of cons. Here they are:

  • It can be a little pricey for individuals and small brands
  • The low-end plans lack features


SwaggerHub is a favorite among techies and software developers. This is no doubt in connection to its ease of use, interactivity, fully hosted, and an array of other convenient features. It is more than just a documentation tool. Putting things in perspective, it has SmartBear support, an open-source API editor, and an interactive documentation tool.

SwaggerHub is a powerful visual tool that lets API providers create interactive documentation for their APIs, letting API providers see exactly how the contract will work before integrating it into any code.

Swagger Hub API Documentation Tool Website Screnshot

The pros and cons of Swagger are as under.


  • It has a free tier for indie developers and solopreneurs.
  • It is quite easy to use, even for beginners.
  • SwaggerHub has the capabilities to execute API calls from the documentation
  • Can deploy API to AWS Lambda and AWS API Gateway


  • The team plan is $90 a month when paid annually.
  • Compatibility issues with cloud microservices


Spotlight is the way to go for a design-centric developer. Spotlight makes documenting your API easy with its built-in features. With automatic updates, accurate API documentation can be generated in a timely manner without having to manually update any of it yourself! Spotlight also helps you save time on the tedious task of updating and maintaining documentation for each change made to an API.

Spotlight API Socumentation Tool Website Snapshot

It also allows its end users the option to choose between JSON schema and openAPI-based API designs. A big plus of Stoplight is the ability to test designs out in real-time.


  • Feature-loaded API design studio
  • Optimized guide design features


  • The free plan has limited design options


ReadMe is another favorite among many developers, thanks to its simplicity and ease of use. The tool also has several features that make it easy to generate streamlined documents.

Readme allows you to create beautiful, interactive API documentation with the power and convenience of a drag-and-drop editor. It allows API providers to add API keys directly in the docs and auto-generate code samples. This feature allows developers to make real API calls effortlessly.

Readme API Documentation Tool Website Snapshot

ReadMe also has a rich gallery of documentation design templates.


  • Interactive and responsible API development tool
  • Pretty fast way of launching APIs
  • Well loaded documentation design templates


  • Limited third-party service integrations


Postman’s machine-readable API documentation tool makes it quite easy for developers to publish their documents quickly and on the go.

Postman’s API documentation builder is an easy way to create interactive and machine-readable API documentation. Postman allows developers to automatically pull in sample requests, headers, and code snippets for new or existing APIs to build docs quickly. Postman makes it easy to publish documentation with dynamic examples and machine-readable instructions.

Postman API Documentation Website Snapshot


  • Proper communication with machine-readable comments
  • Automatic updates on all API documents


  • Complicated UI
  • Steep learning curve

LucyBot DocGen

This is your best bet for non-commercial usage. It is highly customizable for amateurs and pros because it allows them to customize the documentation pages with  HTML and Markdown.

In general, the documentation pages come in the form of CSS, Javascript, and HTML assets. The documentation tool also produces a doc for each method, request, endpoint, and response.

Lucy Bot Doc Gen API Doc Tool Website Snapshot


  • Highly customizable
  • Simple to use


  • Not ideal for individuals and small enterprises


DapperDox is an OpenAPI renderer with an open-source server. You can integrate OAS 2.0 and OAS 3.0 with their OpenAPI specifications via GitHub Flavored Markdown (GFM). Using the API explorer in the tool’s interface, users can tinker with the different document features available.

It is one of the easiest API documentation tools for bringing together guides, documentation, specifications, and diagrams.

DaperDox API Documentation Tool Website Screenshot


  • Very easy to use
  • A rich gallery of themes


  • Irregular updates


This API documentation tool creates API documentation from AsyncAPI 1.x, OpenAPI 2.0, and Swagger 2.0. A new feature on the documentation tool allows you to output HTML directly.

The interface shows a three-column page. The first, second, and third columns contain the explorer, description, and console, respectively. The console is a new feature on the platform for making API calls.

It has a rich lineup of templates that can be customized according to individual needs.


  • Non-clustered UI
  • Users can create HTML as well as markdowns


  • Not so affordable

OpenAPI Viewer

Just like the name suggests, OpenAPI Viewer is a powerful OpenAPI 3.0 and 2.0 spec, viewer. It also works with or without a framework. One of its biggest perks is its customization, branding, and personalization capacities. Putting things in perspective, one can add external contents like links, forms, images, and different forms of media to the top and bottom of their documents.


  • Easily customizable
  • Very easy to use
  • Supports a lot of authentication like HTTP Bearer and HTTP Basic


  • The free version doesn’t contain as many helpful features


RapidDoc has one of the best API documentation tools and UI interfaces. This interface is structured like that of SwaggerUI, such that you have a single column with collapsible bars. Each bar contains a console and its corresponding JSON payloads.

The flexibility of this tool allows you to customize the theme, colors, and font of your documents and UI interface. There is also a provision for embedding external HTML code in the document.


  • Great looking UI
  • Comes with a lot of themes
  • Web component standard
  • Integrated console
  • Supports Markdown


  • Does not support a wide range of extensions

How to choose the right tool?

Identify what your goal(s) are

  • To provide a specific experience to users (code samples, language selection options, copy functionality, interactivity)
  • To showcase APIs alongside documentation
  • To make life easy for documentation authors
  • To provide users with try-out possibilities / functionalities to play around with your APIs

What pain points will you come up against?

  • Technical learning curve to achieve desired outcome
  • Coming up against a paywall for useful features or flexibility
  • Unable to grow outside the constraints of the tool as your API program expands
  • Security policies
  • Responsiveness
  • What content to include and how to structure it


 Any software developer who is serious about their work should make sure they have access to good documentation tools. There are a wide variety of free Software as a Service ( SaaS ) products that can help you with this task. And yes, there are even some free tools that you can use on your own server if you want to.

When you create an app, you also have to make sure people can use it. A step in that process is documentation. Documentation usually involves writing about the purpose of each function as well as the required and optional parameters. If your application is particularly complex or feature-rich, this may be a daunting task. Thankfully, there are quite a few tools that can help you with documentation. You’ve heard of Apiary before and Draft has been out for some time to generate docs in multiple languages through templates.

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