Tolgee

Tolgee is an open‑source, self‑hosted localization platform that replaces commercial services such as Crowdin or Lokalise. From a developer’s perspective it is a full‑stack, micro‑service oriented application written primarily in Kotlin/Java on the backend and React with TypeScript on the frontend. The core goal is to expose a rich API surface, an SDK for in‑app editing, and command‑line tooling that can be integrated into any CI/CD pipeline. By shipping the platform as a Docker image, it also supports Kubernetes and other container orchestration solutions out of the box.

Key Features

• In‑context editing – The JavaScript SDK injects a lightweight overlay that lets users click an element in the running app and instantly edit its translation. The SDK is agnostic to frameworks (React, Vue, Angular) and can be used in both development and production environments.
• CLI & REST API – Export/import of translation files (JSON, PO, XLIFF) is available via a command‑line tool that wraps the same REST endpoints used by the web UI. This makes it trivial to sync translation assets between local repositories and the Tolgee server during CI builds.
• Screenshot capture – A one‑click screenshot tool highlights translatable strings and stores the image in the project, streamlining visual QA for translators.
• Figma plugin – Direct integration with Figma allows designers to export text layers as keys, keeping design and localization in sync.

Technical Stack

The backend follows a clean architecture with bounded contexts: Project, Translation, User, and Audit. Each context exposes a RESTful interface that is versioned (/api/v1/...). The database layer uses optimistic locking and audit tables to guarantee consistency during concurrent edits.

Core Capabilities

• SDKs – JavaScript, Kotlin/Android, Swift/iOS, and a generic REST client library.
• Webhooks – Trigger events on key creation, translation updates, or project changes; useful for notifying downstream services.
• Role‑based access control – Fine‑grained permissions per project and per key.
• AI translation integration – Optional plug‑in for third‑party AI services, callable via the API.
• Export formats – PO, XLIFF, JSON, CSV, and custom templates.

Deployment & Infrastructure

Tolgee is designed for self‑hosting with minimal operational overhead. A single Docker container can run a full instance, but for production you’ll typically deploy the API and database in separate pods. The official Helm chart automates deployment to Kubernetes, handling secrets via K8s Secret objects and providing horizontal scaling for the API pods. PostgreSQL can be run in a stateful set or an external managed database; Redis is optional but recommended for caching.

Scalability is achieved through stateless API pods and a dedicated search cluster. The platform can handle thousands of concurrent editors, as the SDK communicates over WebSocket for live updates.

Integration & Extensibility

Tolgee’s plugin system is built around Java interfaces that can be implemented in separate JARs. This allows custom authentication providers, storage backends, or translation services to be dropped into the platform without touching core code. The public REST API is versioned, so third‑party tools can evolve independently. Webhooks and the Figma plugin expose hooks for further automation.

Developer Experience

• Configuration – All runtime parameters are exposed via environment variables or a YAML config file. The Docker image comes with sensible defaults, and the Helm chart supports custom values files.
• Documentation – The ReadTheDocs site contains comprehensive API references, SDK guides, and a “Getting Started” section that walks through installing the Docker image, creating a project, and adding translations via the CLI.
• Community – Active GitHub discussions, a Slack channel, and a growing number of contributors keep the project responsive. The Apache 2.0 license removes any licensing constraints, making it attractive for commercial deployments.

Use Cases

Advantages Over Alternatives

• Zero vendor lock‑in – Open source with a permissive license; no subscription fees.
• Full API coverage – Every UI action is mirrored in the REST API, enabling complete automation.
• **Low operational