Undertone

Shows translations under Discord messages

A BetterDiscord plugin. In the servers you pick (or all of them), it translates messages into your language and shows the translation under the original in grey.

You can also write in your own language and send the message translated.

Formerly Mollu. If you used Mollu, take the update as usual: it switches you to Undertone and brings your settings and API keys along.

Installing

  1. Download Undertone.plugin.js above. It’s a single file.

  2. In Discord, open BetterDiscord settings → Plugins → Open Plugins Folder and drop the file in.

  3. Turn on Undertone in the plugin list.

  4. In Undertone’s settings, pick a service under Translation backend and paste your API key. See “Getting an API key” below.

  5. Right-click a server icon and turn on Translate with Undertone, or turn on Translate in every server in settings.

Before you start

  • On Google Gemini’s free tier, what you send is used to improve Google’s products. Since the plugin sends other people’s messages from your servers, their conversations become training data. The paid tier is not affected.
  • Your API key and cached translations are stored unencrypted in Undertone.config.json in the plugins folder. Don’t share that file or show it on screen.
  • With outgoing translation on, what you type is replaced by the translation before it is sent, so others never see your original.

Features

  • Turn on Translate direct messages to translate DMs and group DMs too. Off by default.
  • Pick from 15 languages. Messages already in that language are skipped.
  • Automatic mode translates what is on screen. Manual mode only translates what you click.
  • Remembers translations, so repeated sentences cost nothing extra.
  • Right-click a channel to leave it out, or a message to hide its translation or translate it again.
  • Ctrl+Shift+T toggles automatic translation, Ctrl+Shift+O toggles outgoing translation. Change them under Fine-tuning in settings.
  • Checks the signature of new versions and asks before installing.

Getting an API key

Translation runs through an outside service, so you need an API key. DeepL is the easiest free start. DeepSeek, Gemini, OpenAI and Claude keep tone and slang better.

Service Cost Get a key
DeepL 500,000 characters a month free deepl.com/pro-api
Google Gemini Has a free tier aistudio.google.com
DeepSeek Paid, very cheap platform.deepseek.com
OpenAI Paid, default model is cheap platform.openai.com
Anthropic Claude Paid platform.claude.com

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