Crowdin Apps SDK

The Crowdin Apps SDK is a Node.js framework for building self-hosted apps. You describe the app in a configuration object, and the SDK builds the Express application around it, with the endpoints Crowdin calls already in place.

Because they run on your own server, self-hosted apps support every module type, including file processing, AI providers, custom machine translation engines, and webhooks.

What the SDK Handles

• Authentication: OAuth 2.0 with the crowdin_app grant type, JWT validation, and context extraction.
• Modules: Registration and the endpoints each module type expects.
• Database: SQLite by default, with PostgreSQL and Cloudflare D1 as options.
• File storage: Temporary files for file processing modules.

Building a Self-Hosted App

Install the package:

npm install @crowdin/app-project-module

createApp creates the Express application from your configuration. If you already have an Express application, addCrowdinEndpoints adds the Crowdin endpoints to it.

The SDK requires Node.js 20.11 or later and Express 5. Apps built with it deploy to Vercel, AWS Lambda, and Cloudflare Workers.

Crowdin Apps SDKConfiguration, modules, database, deployment, and security guides.

When to Build a Serverless App Instead

If your app is all interface (a dashboard, an editor panel, a menu extension), you can build it as a serverless app: Crowdin hosts and runs it, and there is no server to deploy or maintain.

Read more about the Serverless Apps SDK.