Tolgee is an open-source localization platform designed for developers and translators who need to manage app translations without disrupting the development workflow. It solves the pain point of manual copy-pasting between code files and translation tools by allowing real-time, in-context editing of text directly in the running application—whether in development or production. With support for major frameworks like React, Angular, Vue, and Svelte, Tolgee integrates seamlessly into existing tech stacks and reduces dependency on developers for simple text changes.
Built with TypeScript and Kotlin, Tolgee provides a self-hostable platform with Docker support, REST API, CLI tools, and SDKs for frontend frameworks. It leverages machine translation services like DeepL, Google Translate, and AWS Translate, and includes translation memory, activity logs, and an MCP server for AI coding assistants. Deployment options include cloud-hosted (app.tolgee.io) and self-hosted via Docker or Kubernetes.
What You Get
- In-context translation - Edit text directly in your running app by holding ALT/Option and clicking any element; changes are saved to Tolgee without touching code files.
- Production-ready in-context editing - Use the Tolgee Chrome extension to translate live production apps by entering your API key—no developer access required.
- AI-powered machine translation - Automatically translate new strings using DeepL, Google Translate, or AWS Translate with context-aware accuracy.
- Translation memory - Suggest previously used translations based on similarity percentage, key, and original text to ensure consistency across projects.
- Auto-translation - Automatically translate new keys using translation memory or machine translation services upon creation, accelerating localization workflows.
- MCP Server integration - Enable AI coding assistants (like GitHub Copilot or Cursor) to search, create, update, and manage translations directly from your IDE without leaving your editor.
- Figma plugin integration - Import text from Figma designs directly into Tolgee projects to synchronize UI copy with design files.
- CLI and REST API - Import/export translation files via command line or REST endpoints for CI/CD automation and bulk operations.
- Translation history & comments - Track every change to a translation key, see who made edits, and leave contextual feedback on translations.
- Activity log - View a full audit trail of who modified, reviewed, or commented on any translation in your project.
Common Use Cases
- Running a multi-language SaaS product - A product team uses Tolgee’s in-context editor to let non-technical stakeholders edit UI text in production without waiting for dev cycles.
- Localizing a React or Vue web app with AI - A developer integrates the Tolgee JS SDK to auto-translate new keys using DeepL and translation memory, reducing manual translation workload by 70%.
- Managing translations for a client-facing platform - A freelance developer deploys Tolgee with the Chrome extension so clients can update button labels and banners themselves without code access.
- Scaling localization in a CI/CD pipeline - A DevOps team uses the Tolgee CLI to sync translation files during build steps and triggers machine translation on new keys before deployment.
Under The Hood
Architecture
- Clean separation of concerns through a modular monolith structure with well-defined Gradle subprojects and explicit dependency boundaries
- Layered design using Spring Boot annotations to decouple HTTP handling, business logic, and data access, with DTOs enforcing immutable data contracts
- Assembly patterns like PublicConfigurationAssembler ensure clean transformation between domain models and external API representations
- Independent deployment pipelines for frontend and backend, maintaining cohesive release semantics across polyglot components
Tech Stack
- Java and Kotlin backend powered by Spring Boot and Gradle, with structured dependency management and Kotlin’s expressive syntax for core modules
- Vue.js frontend with Vite for fast development and environment-aware API configuration via .env.local files
- Automated versioning and release pipelines using semantic-release, with JAR packaging and changelog generation
- Ktlint and EditorConfig enforce consistent code formatting across Java and Kotlin codebases
- Gitpod and Ngrok enable seamless full-stack development with parallel server initialization and local tunneling
Code Quality
- Extensive test coverage spanning unit, integration, and security-focused scenarios, including detection of XML-based vulnerabilities
- Custom test utilities and assertions enhance readability and reduce boilerplate while maintaining precision in API and service validation
- Clear layering of test fixtures, service layers, and repository mocks ensures maintainability and isolation
- Strong type safety, comprehensive validation, and descriptive naming conventions improve code clarity and reduce runtime errors
- Robust CI/CD infrastructure with Redis, Spring context management, and mock injection for reliable, repeatable test execution
What Makes It Unique
- Dynamic machine translation powered by LLM properties enables context-aware translation without external API dependencies
- Server-driven frontend configuration auto-injects authentication, billing, and analytics settings at runtime, eliminating hard-coded environment variables
- Unified HATEOAS-based API assembly dynamically enriches responses with user metadata and avatar links in a type-safe, reusable manner
- Pluggable subscription system renders organization-specific billing plans using generated OpenAPI schemas and reactive hooks
- Abstracted file storage layer supports multiple backends while serving assets through a unified URL scheme, decoupling UI from storage logic
- Pluggable SSO and authentication system exposes enterprise identity provider integration as first-class public API endpoints