scalar

Scalar UI integrates the Scalar open-source API documentation library into Drupal,
providing a modern, beautiful, and interactive interface for rendering OpenAPI specifications directly on your Drupal site.
This package contains two sub-modules: OpenAPI UI Scalar (openapi_ui_scalar) for rendering OpenAPI specs through the OpenAPI UI plugin architecture, and Scalar UI Formatter (scalar_ui_formatter) for embedding interactive API documentation
inside any field using Drupal's Field Formatter system.

If you expose REST, JSON:API, or any other OpenAPI-described service from your Drupal site, Scalar UI gives your
developers and API consumers an elegant, fully interactive reference - without leaving your Drupal environment.
Scalar is MIT-licensed, actively maintained, and widely regarded as one of the most polished open-source API
documentation UIs available today.

Features

This module package bridges Drupal's OpenAPI ecosystem with the Scalar library, offering two distinct integration paths:

openapi_ui_scalar plugs directly into the
OpenAPI UI module's plugin architecture. Once enabled, Scalar
becomes selectable as the UI renderer on any OpenAPI UI display page - the same way you would choose Swagger UI or
ReDoc. This is the recommended approach when you use the
OpenAPI,
OpenAPI JSON:API, or
OpenAPI REST modules to expose Drupal's API documentation.

scalar_ui_formatter is a standalone field formatter for file fields and link fields containing an
OpenAPI document URL or uploaded .json / .yaml specification file. It renders the Scalar
widget inline within any node, paragraph, or other entity display - making it straightforward to embed API
documentation alongside other content, such as developer portal pages or documentation articles.

Key features include:

Modern, responsive API documentation UI with built-in dark/light mode support
Interactive "Try it out" API console allowing users to make live requests from the browser
Support for OpenAPI 3.x specifications
Zero external SaaS dependency - Scalar renders entirely client-side with no external calls required
Plugin-based integration with OpenAPI UI, making Scalar interchangeable with Swagger UI and ReDoc
Field formatter integration for embedding API docs directly in content
Configurable CDN or local library loading
Accessible and keyboard-navigable interface

Post-Installation

After installing this module via Composer (composer require drupal/scalar), enable one or both
sub-modules at Admin → Extend.

Using openapi_ui_scalar with OpenAPI UI: Navigate to any path that uses the OpenAPI UI display,
such as those provided by the OpenAPI JSON:API or
OpenAPI REST modules. Go to
Admin → Configuration → Web Services → OpenAPI and select Scalar as
the UI plugin. Save the configuration and visit your OpenAPI documentation path to see Scalar rendering your spec.

Using scalar_ui_formatter as a field formatter: Go to
Admin → Structure → Content Types → [Your Type] → Manage Display. For any
file field or link field that holds an OpenAPI document, select Scalar API Viewer as the formatter.
Configure the formatter settings (such as layout mode and theme) and save. When content with that field is viewed,
the Scalar interactive UI will render inline.

The Scalar JavaScript library is loaded either from a CDN (default, no extra setup needed) or from a local
installation under /libraries/scalar if you prefer to self-host it. Library configuration is available
at Admin → Configuration → Development → Scalar UI Settings.

Additional Requirements

The following are required depending on which sub-module you use:

Drupal 10 or 11 (both supported)
OpenAPI UI - required by
openapi_ui_scalar only. Provides the plugin architecture that this module implements.
Scalar JavaScript library - the
@scalar/api-reference library (MIT licensed). Can be loaded via
CDN automatically, or installed locally via Composer asset management or manual download to
/libraries/scalar.

To install the Scalar library locally via Composer, add the following to your project's composer.json:

"extra": {
  "installer-paths": {
    "web/libraries/{$name}": ["type:drupal-library"]
  }
}

Then run:

composer require scalar/scalar-api-reference

Recommended Modules/Libraries

OpenAPI - the base module for generating and serving OpenAPI
specifications from your Drupal site. Pair with the sub-modules below.
OpenAPI JSON:API - generates an OpenAPI spec for
Drupal's core JSON:API endpoints, which Scalar can then render.
OpenAPI REST - generates an OpenAPI spec for Drupal's
REST module endpoints.
OpenAPI UI - required for
openapi_ui_scalar; the shared plugin framework that allows switching between different API UI renderers.

Similar Projects

Several other Drupal modules render OpenAPI specifications. Here is how Scalar UI compares:

Swagger UI for OpenAPI UI -
The most widely deployed option (~6,000 reported installs). Uses the battle-tested Swagger UI library.
Scalar UI offers a more modern aesthetic, a built-in dark mode, and a cleaner reading experience, while
providing the same try-it-out console functionality.
Swagger UI Formatter -
Provides a Swagger UI field formatter without requiring the OpenAPI UI module. The
scalar_ui_formatter sub-module fills the same role with the Scalar library instead.
ReDoc for OpenAPI UI - ReDoc is a documentation-focused renderer with a clean three-panel
layout, but it does not include a built-in API console for making live requests. Scalar provides both
rich documentation display and an interactive console in a single library.

Supporting This Module

This module is maintained by volunteers. If you find it useful, you can support its continued development in the
following ways:

Report issues and review patches in the
issue queue on Drupal.org.
Contribute code via the
GitLab repository.
Sponsor the upstream Scalar project via their
GitHub repository - a healthy upstream means a better module
for everyone.

Community Documentation

Scalar official website - learn about the upstream Scalar library, its
features, and configuration options.
Scalar on GitHub - source code, changelog, and issues for
the underlying JavaScript library.
OpenAPI UI module - documentation on the plugin
architecture that openapi_ui_scalar implements.
OpenAPI module - documentation on generating OpenAPI
specs from your Drupal site's APIs.