Compare Lumo by Proton vs ProWritingAid vs Onyx
| Feature | Lumo by Proton | ProWritingAid | Onyx |
|---|---|---|---|
| Description | Lumo is Proton's AI assistant for questions, writing help, and file chats, built so your conversation history stays encrypted and private. A free plan lets anyone try it, and Plus adds unlimited chats for people who want privacy-first help every day. | ProWritingAid helps writers improve grammar, style, and story structure with reports and AI rewrites. A free tier lets you start, and Premium plans add deeper critique tools for people finishing books and long documents. | A self-hosted AI chat and search platform that connects to your team's documents and apps. Built for: Small teams who want an AI assistant over their shared knowledge. Format: Self-hosted web app (Docker). License: Open-core: MIT, except ee/ directories (Onyx Enterprise License). Open source on GitHub (32,407 stars as of 2026-10-11). |
| Pricing | Free $0; Lumo Plus $12.99/mo monthly or $9.99/mo billed yearly ($119.88/yr) | Free tier available; Premium about $30/mo monthly or $10/mo billed yearly ($120); Premium Pro about $36/mo monthly or $12/mo yearly; lifetime options listed | Free and open source (open-core: some features are paid); self-hosting, model or API costs may apply |
| Main category | Chat assistants | Writing | Research and notes |
| Website | Visit Lumo by Proton | Visit ProWritingAid | Visit Onyx |
| Info last checked | October 17, 2026 | October 14, 2026 | October 13, 2026 |
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