Free trial
The free plan doubles as a trial: no credit card is needed, and accounts can be created at any time to test the assistant before upgrading. No separate timed trial is advertised.
Learn moreLumo by Proton
Proton's encrypted AI chat assistant with no logs and no training on your data
Beginner
Own Lumo by Proton? Verify ownership to get a dofollow link
What is Lumo by Proton?
Lumo by Proton is an AI chat bot tool. Lumo is Proton's privacy-first AI chat assistant. It answers questions, generates images, summarizes documents and searches the web, while storing every conversation under zero-access encryption that Proton cannot read. Free tier available; Lumo Plus adds higher limits and unlimited projects.
Lumo is a chat-based AI assistant built by Proton, the team behind Proton Mail and Proton VPN. It handles the familiar assistant tasks: answering questions, summarizing documents, drafting reports, generating images from text prompts, planning workloads, and digging through confidential research. What separates it from mainstream chatbots is the storage model. Conversation history is kept under zero-access encryption, meaning the archive can only be decrypted on your device and Proton itself cannot read it. The product also states that chats are not used to train models and are never shared with advertisers or governments. The service sits well with individuals and teams who handle material they would rather not paste into a consumer chatbot: client contracts, health questions, visa paperwork, tax filings, school applications, internal reports. Proton positions it toward both personal users and businesses, with a separate Lumo for Business offering that keeps team conversations encrypted and under organizational control. A free tier covers limited use of the Max model, limited messages and history, limited image generations and one project, while Lumo Plus raises those ceilings, adds unlimited projects and custom Lumos, and bills monthly or yearly with a 23 percent annual discount. Prices are quoted in CHF, EUR and USD. In practice Lumo works like any chat assistant: open a session in the browser, type a prompt (the homepage caps a single input at 1,800 characters when starting a chat), or ask it to produce an image. Projects and Custom Lumos let you organize recurring work and presets. A built-in web search returns current information, and Proton Drive files and folders can be linked into a conversation so the assistant works with your own documents. Guest access over Tor lets you try the assistant without an account. Against ChatGPT, Gemini, Copilot and Claude, the pitch is jurisdictional and architectural rather than raw capability. Lumo is built and hosted in Europe, complies with GDPR, publishes its client code as open source so outsiders can verify the privacy claims, and runs on an ad-free business model. Choosing it means accepting a smaller ecosystem in exchange for a conversation history that stays sealed.
How do you use Lumo by Proton?
1Open Lumo in the browser
Go to the Lumo web app and start a chat directly, or connect over Tor for guest access without creating a Proton account.
2Create a Proton account for saved history or Plus
Signing up unlocks encrypted chat history, projects and the paid tier. The plan picker lets you choose free or Lumo Plus, monthly or yearly.3Ask your first question or request an image
Type a prompt into the input box, keeping it under the 1,800 character limit for a new chat, or describe a visual to generate an image.4Link Proton Drive files into the conversation
Attach files and folders from Proton Drive so Lumo can review documents and reports without the data leaving your encrypted storage.5Set up projects and custom Lumos
Group recurring work into projects and save reusable custom Lumos presets. The free plan allows one project; Plus removes the project cap.6Review how your data is protected
Read the security model and open source pages to understand the encryption architecture before trusting sensitive material to the assistant.
Pros and cons
Pros
- Zero-access encryption keeps chat history readable only on the user's deviceAI
- Open source client code lets outsiders verify the privacy and no-training claimsAI
- No account needed for a basic session, and guest access over Tor is supportedAI
- European hosting under GDPR, outside US jurisdiction, from the Proton Mail teamAI
- Free tier plus a clearly priced Plus plan with an annual discount and money-back guaranteeAI
Cons
- Single prompt input is capped at 1,800 characters when starting a chat, which is tight for pasting long documentsAI
- Free tier limits Max model usage, message history, image generations and projects, so heavier users are pushed to PlusAI
- No public API appears on the homepage, so it cannot be wired into custom pipelinesAI
- Feature depth is described loosely; there is no detailed model or benchmark documentation on the pageAI
- Image generation and web search are the only listed extras, so it is a narrower toolkit than mainstream assistantsAI
How much does Lumo by Proton cost?
Pricing
Free tier at $0.00 with no credit card required, offering limited Max model usage, messages, chat history, image generations and one project. Lumo Plus is $9.99 per month on annual billing ($119.88 per year, 23 percent off) or $12.99 monthly, with more of everything, unlimited projects and custom Lumos. Either plan carries a 30-day money-back guarantee.
Learn moreSupport
Support details are not described on the homepage beyond self-serve resources: the security model write-up, the open source code listing, the trust center and the AI guide pages.
Learn moreIntegrations
The homepage mentions linking files and folders from Proton Drive into conversations. No other third-party integrations are listed, and no public API is described.
Features
Text chat with the Max model, text-to-image generation, web search for current information, document and data analysis, project organization, custom Lumos presets, and Proton Drive file linking. History is stored with zero-access encryption, chats are never used for model training, and the client code is open source.
Learn moreFrequently asked questions about Lumo by Proton
How much does Lumo by Proton cost?
Free tier at $0.00 with no credit card required, offering limited Max model usage, messages, chat history, image generations and one project. Lumo Plus is $9.99 per month on annual billing ($119.88 per year, 23 percent off) or $12.99 monthly, with more of everything, unlimited projects and custom Lumos. Either plan carries a 30-day money-back guarantee.Does Lumo by Proton offer a free trial?
The free plan doubles as a trial: no credit card is needed, and accounts can be created at any time to test the assistant before upgrading. No separate timed trial is advertised.How do you use Lumo by Proton?
The walkthrough on this page covers 6 steps: 1. Open Lumo in the browser 2. Create a Proton account for saved history or Plus 3. Ask your first question or request an image 4. Link Proton Drive files into the conversation 5. Set up projects and custom Lumos 6. Review how your data is protected.What platforms does Lumo by Proton support?
Lumo by Proton is available on Web App.What does Lumo by Proton integrate with?
The homepage mentions linking files and folders from Proton Drive into conversations. No other third-party integrations are listed, and no public API is described.What are the limitations of Lumo by Proton?
Single prompt input is capped at 1,800 characters when starting a chat, which is tight for pasting long documents. Free tier limits Max model usage, message history, image generations and projects, so heavier users are pushed to Plus. No public API appears on the homepage, so it cannot be wired into custom pipelines.
Status
StatusActive
Views0
Outbound clicks0
Added10/22/2026
Platforms
Web App
Pricing
FreeFreemiumSubscription
