A Thunderbird add-on that brings ChatGPT, Gemini, Claude or Ollama into your mailbox to reply, proofread, translate, summarize and tag emails.
368+5 this week66JavaScriptGPL-3.0Well maintainedUpdated yesterday
1 alternative
Best open-source alternatives to Microsoft Copilot in Outlook (2026)
Looking for a free, open-source alternative to Microsoft Copilot in Outlook? These 1 projects can replace it. Each one passed our quality screening and is explained in plain words, so you can compare stars, license and maintenance at a glance.
Quick comparison
| Project | Stars | License | Last commit |
|---|---|---|---|
| micz/ThunderAI | ★ 368 | GPL-3.0 | yesterday |
FAQ
- Is there a free, open-source alternative to Microsoft Copilot in Outlook?
- Yes. The most popular open-source alternatives to Microsoft Copilot in Outlook on Repolode are ThunderAI.
- Which Microsoft Copilot in Outlook alternative should I choose?
- ThunderAI has the most GitHub stars and is released under GPL-3.0. Compare the license and last commit of each option in the table above before choosing.
How this list is made: AI reads each project's documentation to match it with products it can replace, every project passes our quality screening, and the list is ranked by GitHub stars. Stars updated Nov 7, 2026. How Repolode works