How to integrate Scalar with FastAPI?

Scalar has a dedicated FastAPI integration plugin that automatically generates and serves OpenAPI specs with interactive documentation. You can install it via package managers and configure middleware for real-time API testing and exploration.

Scalar vs Postman which is better for OpenAPI?

Scalar excels with its deep OpenAPI integration, modern UI, and offline-first client, making it ideal for teams focused on specification-driven development. Postman offers broader protocol support and collaboration features but may feel clunkier for OpenAPI-centric workflows.

Is Scalar API client free for commercial use?

Yes, the Scalar API client is open-source and free to download for all major desktop OSes, as stated on the download page. However, managed hosting and advanced features like GitHub Sync may require paid plans.

Does Scalar support GraphQL APIs?

No, Scalar is specifically designed for REST APIs using OpenAPI specifications. For GraphQL, you need alternative tools like GraphiQL or Apollo Studio that are built for GraphQL schemas and queries.

How to customize Scalar API reference theme?

Scalar provides extensive theming options through a universal configuration object, allowing you to modify layouts, colors, and styles via documented themes and customization settings on their website.

Can Scalar generate SDKs for my API?

Scalar includes code generation for client snippets in many languages, but full SDK generation is part of the separate Scalar SDKs project, which may require additional setup or managed services.

Open-Awesome

Scalar

MITTypeScriptrelease-2026-07-20-be8106c

An open-source API platform providing a modern REST API client and beautiful API references with first-class OpenAPI/Swagger support.

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15.7k stars902 forks0 contributors

What is Scalar?

Scalar is an open-source API platform that provides a modern REST API client and interactive API reference documentation. It solves the problem of outdated, clunky API tooling by offering a beautiful, integrated experience for testing, documenting, and exploring APIs, with native support for the OpenAPI/Swagger specification.

Target Audience

API developers, backend engineers, and technical writers who need to build, test, document, and share RESTful APIs. It's especially valuable for teams adopting OpenAPI standards across various frameworks.

Value Proposition

Developers choose Scalar for its modern design, first-class OpenAPI support, and the seamless integration between its API client and reference documentation, offering a cohesive alternative to fragmented, legacy tools.

Overview

Scalar is an open-source API platform:　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　🌐 Modern REST API Client　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　📖 Beautiful API References　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　✨ 1st-Class OpenAPI/Swagger Support

Use Cases

Best For

Creating interactive API documentation from OpenAPI/Swagger specs
Testing REST APIs with a modern, offline-first desktop client
Integrating API references directly into web applications built with frameworks like Next.js or React
Teams needing a Postman alternative with strong OpenAPI support
Generating client SDK code snippets for multiple languages
Developing APIs with frameworks that have built-in Scalar support like ElysiaJS or FastAPI

Not Ideal For

Projects that do not use OpenAPI/Swagger specifications
Teams requiring fully static, zero-JavaScript API documentation for server-side rendering
Developers working primarily with non-REST APIs like GraphQL or gRPC
Environments where offline use of the API client is unnecessary and a web-only tool suffices

Pros & Cons

Pros

Modern API Client

Offers an offline-first desktop application with first-class OpenAPI support, environment variables, and dynamic parameters, as highlighted in the 'An offline-first API Client built for OpenAPI' section.

Interactive Documentation

Renders OpenAPI/Swagger documents into beautiful, modern references with integrated testing tools, explicitly designed to avoid outdated interfaces.

Extensive Framework Integrations

Provides plugins for dozens of frameworks like FastAPI, Express, and Hono, making it easy to integrate into existing projects, with some frameworks adopting it as the default UI.

Code Generation

Automatically generates code examples for many languages and frameworks from the API spec, aiding in client SDK development directly from the documentation.

Cons

JavaScript Dependency

The API reference component loads via JavaScript CDN, requiring client-side execution, which may not suit environments with JS disabled or strict server-side rendering needs.

Setup Complexity for Integrations

Some integrations, like handling CORS with a proxyUrl as shown in the Quickstart, add configuration steps that can be cumbersome compared to drop-in solutions.

OpenAPI-Centric Limitations

Primarily focused on OpenAPI, with limited or no native support for other API specs like GraphQL, which restricts its utility in polyglot API environments.

Open Source Alternative To

Scalar is an open-source alternative to the following products:

Postman

Postman is a collaboration platform for API development that allows developers to design, test, and document APIs.

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