A Lumo alternative with frontier models

What Lumo does well

Details about Lumo come from its own website, checked on October 14, 2026. Products change quickly, so confirm them at the source before you decide. Proton describes Lumo as zero-access encrypted, with a no-logs policy, so Proton itself says it cannot read your saved chats. It says it never trains on your conversations, and its code is open source. It is run by Proton, a company based in Europe, and has a free tier and a paid Plus plan. Zero-access encryption is a stronger technical guarantee than Quad offers. If that is your requirement, Lumo is the right choice, and Quad does not claim otherwise.

Where Quad is different

Models (Quad: GPT-6, Claude, Gemini, Grok, DeepSeek and more, picked by you per chat; Lumo: Proton's own model setup; its homepage does not name the models). Training on your chats (Quad: Never, on any plan; Lumo: Never, per Proton). Encryption (Quad: In transit and at rest; Lumo: Zero-access encryption, per Proton). Stored history (Quad: Kept, encrypted, so it syncs across devices; Lumo: No-logs policy, per Proton). Open source (Quad: No; Lumo: Yes, per Proton). Price to start (Quad: Free, 100 credits a month; Lumo: Free tier, Lumo Plus at $9.99 a month, per Proton). The honest summary is a trade between guarantee and capability. Lumo gives you a stronger confidentiality guarantee. Quad gives you the newest models from every major lab, plus Image Studio, documents and slides, and a desktop agent, with privacy commitments that are specific and checkable.

What Quad promises, exactly

Quad never uses your chats or files to train AI models, on any plan, free included. Quad never sells your data and never shares workspace content with advertisers. 47 of 51 chat models run on the Private Lane, which sends chats only to providers under a Zero Data Retention agreement. The other 4 ask you to confirm before you use them. Chats and files are encrypted in transit and at rest, and you can export or delete them yourself. Incognito chats stay out of your history and skip memory, and their temporary data is deleted within an hour. Quad stores your history, encrypted, so it can sync across the web, desktop and phone apps. That makes Quad private, not anonymous, and it is not end-to-end encrypted. The model you pick still reads your prompt in order to answer. See the private AI chat page for where privacy stops.

Which one to use

Choose Lumo when the provider must be unable to read your stored chats. Choose Quad when you want GPT-6, Claude Opus and Gemini, model choice per task, and work beyond chat, without your chats ever training a model. Keep regulated or secret material out of any hosted AI your contract does not allow, on either service. Use both if it helps. Many people keep a zero-access tool for the most sensitive notes and a frontier-model workspace for everyday writing, research and code. Quad's free plan includes 100 credits a month, and guest chat works with no account. See pricing for the paid plans.

Frequently asked questions

Is Quad zero-access encrypted like Lumo?

No. Quad encrypts chats and files in transit and at rest, and keeps history so it can sync across devices. It is not zero-access or end-to-end encrypted, and it does not claim to be.

Which models does Quad have that Lumo does not?

Quad lets you pick GPT-6, Claude Opus 5.5, Gemini, Grok, DeepSeek and more in every chat. Lumo runs Proton's own model setup, and its homepage does not name the models.

Does Quad train on my conversations?

No. Quad never uses your chats or files to train AI models, on any plan, and never sells your data or shares it with advertisers.

Is there a free Lumo alternative?

Yes. Quad has a free plan with 100 credits every month, and guest chat at quad.chat needs no account.