The best alternatives to Slack Translate are Lingvanex, Text/Turner, and LanguageBot. If these 3 options don't work for you, we've listed a few more alternatives below.
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AssemblyAI— Speech-to-Text API with superhuman accuracy
LanguageBot allows international teams & foreign language speaking workers to communicate directly within Slack using /slash commands to translate between languages. Your team can start testing free with 5000 translation credits. Instant, accurate and context aware - Slack button: https://languagebot.io
Translate text into any language from within Slack. You can translate messages from others, your own messages, or any text. Power features include posting translations to the channel and automatically translating all messages posted to a channel.
Transify is a fast and easy solution to language barrier in teams, it's easy to use, all you need to do is use slash commands e.g \spanish. (and many other languages) Translate Slack Messages without leaving slack or opening a new Tab!
Break the language barrier in your teams by automatically translating slack messages into as many languages as you want (supports 100+ languages). Use the app to create multi-language channels for your Slack workspaces.