Lumo by Proton

In-app purchases
3.4K reviews
Content rating
Rated for 3+
100K+
Downloads
Content rating
Rated for 3+
Learn more
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About this app

"Lumo is a zero-access encrypted AI assistant that keeps every conversation private. Your data is never logged, shared, or used to train models. Your chats are yours, and yours alone.

Built by Proton, the privacy brand trusted by over 100 million people and the team behind Proton Mail, VPN, Drive, and Pass.

THOUGHTFUL HELP FOR ANY TASK
Lumo handles everything from quick questions to more complex work. Choose Fast for quick answers or Thinking for multi-step reasoning.

FAST, POWERFUL WEB SEARCH
Get precise, real-time answers in seconds. Lumo cites live sources so you can verify facts, dig deeper, and stay current on news, events, financial data, and more.

CREATE AND REFINE IMAGES AND FILES
Work with images and documents just by telling Lumo what you need, from generating and editing images to analyzing documents. Connect your Proton Drive account for seamless access to stored files.

AI THAT EVOLVES OVER TIME
Lumo gets better every time you use it. Memory retains context and preferences across sessions, and you can set tones and styles to get the exact Lumo experience you want.

STAY PRODUCTIVE AND ORGANIZED
Projects give you dedicated encrypted spaces for tasks that span multiple chats, files, and instructions, while Custom Lumos let you create assistants tailored for specific tasks. Switch between light and dark modes for a more comfortable experience throughout the day.

GHOST MODE
For conversations where you want maximum privacy, choose Ghost Mode. Chats are instantly deleted once you close them for greater peace of mind.

PRIVACY YOU CAN VERIFY
Lumo is founded on zero-access encryption with no server-side chat logs, and never uses your data for profit or model training. Like all Proton products, Lumo is built and hosted in Europe and is fully open-source.

Lumo helps you stay productive, curious, and informed — without ever compromising your privacy. Start a confidential chat for free today.

For more information, visit our website: https://lumo.proton.me/about
Terms of service: https://lumo.proton.me/legal/terms
Terms of use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Our open-source code base: https://github.com/ProtonLumo/ios-lumo"
A private AI assistant by Proton
Updated on
Oct 21, 2026

Data safety

Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
  • No data shared with third parties
    Learn more about how developers declare sharing
  • This app may collect these data types
    Personal info, App activity, and App info and performance
  • Data is encrypted in transit
  • You can request that data be deleted

Ratings and reviews

3.21K reviews
John Doe
November 3, 2026
Not quite there yet, and on some subjects it gives inaccurate or not the best information, but the latest update added a bunch of welcomed features such as conversation history memory. I'd still rather use this AI over many others. Edit November: Lumo has gotten more accurate and careful in giving answers, and instructing it to not agree too easily while providing counterarguments adds another layer of healthy caution.
1 person found this review helpful
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Proton AG
July 3, 2026
Thank you for the review. As with any AI, Lumo can make mistakes. You can use the thumbs down button to share your input with us regarding any inadequate responses. Our team is looking into these reports in order to further improve the quality of the answers in the future.
Kenny Makina
November 3, 2026
used to work great when it came out, but since the release of 2.0 every query I give Lumo always takes at least two attempts. the first attempt always errors, which is very frustrating. I already checked app permission, background activity setting and tried different networks. Maybe the CEO should dial back on his vibecoding regime and let the people build an actually working app that's reliable.
1 person found this review helpful
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Proton AG
November 3, 2026
That doesn't sound right. Could you describe the issue in more detail? What exactly is the error message you're receiving? Are you triggering the issue with some specific prompt(s)? Contact us through the "Help and feedback" → "Report a problem" option under the account menu so we can assist you.
Miss Leya
November 6, 2026
Ever since the most recent update the app won't work It will open up but then it never reaches the point where you can actually use it. I tried uninstalling and re-downloading it and that didn't fix the problem. Prior to this most recent update I loved lumo.
1 person found this review helpful
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Proton AG
November 6, 2026
That doesn't sound right. Could you share more details about the issue? Are you receiving any error messages by chance? What exactly happens when the app loads? Please contact us through the "Help and feedback" → "Report a problem" option under the account menu, or via the contact form on our website, so we can assist you.

What’s new

Lumo 2.1.5 is here, and we’ve chased down a few pesky bugs! We’ve fixed issues with signing in, payments, and file downloads, and reduced memory usage. Less hiss, more purr. 🐾