Mattermost Translate

Translate any message in Mattermost with one click using Google Cloud Translation API v2.

• Adds a “🌐 Translate message” action to each post menu
• Sends the translation back to you as an ephemeral message
• Replies in-thread when the original message is threaded
• Server-side configuration for API key and default target language

Requirements

• Mattermost Server 6.2.1+ (tested on newer versions as well)
• A Google Cloud project with the Cloud Translation API enabled
• A Google API key with access to Cloud Translation API v2

Installation

Install from a release (recommended)

1. Download the plugin bundle tarball from the Releases page (jp.shipmate.mattermost-translate-.tar.gz).
2. In Mattermost System Console, go to:
   • System Console → Plugin Management → Upload Plugin → Upload the tarball
3. Enable the plugin.

Install from source

Prerequisites: Go 1.20+, Node.js 16+, npm 8+, make

• Build and package:
  • make dist
  • The bundle is created at dist/jp.shipmate.mattermost-translate-.tar.gz
• Upload via System Console as above, or deploy to a local server using environment variables:
  • Using personal access token:
    • export MM_SERVICESETTINGS_SITEURL=http://localhost:8065
    • export MM_ADMIN_TOKEN=<your_token>
    • make deploy
  • Using username/password:
    • export MM_SERVICESETTINGS_SITEURL=http://localhost:8065
    • export MM_ADMIN_USERNAME=admin
    • export MM_ADMIN_PASSWORD=
    • make deploy

Configuration

After installation, configure the plugin in System Console → Plugins → Mattermost Translate.

• GoogleAPIKey (required)
  • Your Google API key for Cloud Translation API v2.
  • Create/Manage at https://console.cloud.google.com/apis/credentials and enable the Translation API.
• DefaultTargetLang (optional)
  • ISO language code to translate into by default (e.g. en, ja, es). Default: ja

Click Save when done.

Usage

• Hover a message, open the “…” post menu, and click “🌐 Translate message”.
• The translation will be sent back to you as an ephemeral message.
• If the original message is part of a thread, the reply appears in that thread.

Notes

• If you want to override the target language per request, this can be added in a future enhancement. Currently the server uses DefaultTargetLang when no target is specified by the client.

Troubleshooting

• 401 Unauthorized when calling the API
  • Ensure you are logged in and accessing Mattermost from the same origin (no cross-domain proxy).
  • Clear cache/hard refresh to load the updated webapp.
• Translation returns the original text
  • Verify GoogleAPIKey is valid and the Translation API is enabled in your project.
  • Check DefaultTargetLang is set correctly (e.g. en to translate Japanese → English).
• The menu shows but no response
  • Check System Console → Logs for plugin errors.
  • Re-upload the latest bundle and refresh the client.

Development

• Lint & type-check:
  • make check-style
• Build:
  • make dist
• Watch & auto-deploy to a local server (requires MM_ADMIN_TOKEN and MM_SERVICESETTINGS_SITEURL):
  • export MM_SERVICESETTINGS_SITEURL=http://localhost:8065
  • export MM_ADMIN_TOKEN=<your_token>
  • make watch

Project structure

• server/: Go backend (Mattermost plugin hooks and REST API)
• webapp/: Frontend bundle that registers the post menu action

License

This project is open source. See LICENSE for details.