Lumo is an AI chat assistant launched by Proton that centers privacy, aiming to provide users with a secure and private intelligent conversation experience. It uses zero-access encryption technology to ensure chat content is decrypted only on the user’s device, inaccessible to Proton servers. Lumo does not save any conversation logs nor uses user data to train AI models. It is based on open-source large language models, with transparent and verifiable code, running on Proton-controlled data centers in Europe. Users can use it for free without registration, and logging into a Proton account allows saving encrypted chat records. Lumo also offers a paid Lumo Plus service that unlocks unlimited chatting and more advanced features, combining AI convenience with strict privacy protection, especially suitable for users concerned about data security.
Feature List
- Privacy-Protected Chat: All conversations use zero-access encryption, decrypted only locally on the device, Proton cannot view the content.
- No Log Keeping: Servers do not save any chat data after conversations end, safeguarding user privacy.
- Open-Source Models: Employs open-source language models such as Nemo, OpenHands 32B, OLMo 2 32B, and Mistral Small 3, with publicly accessible and transparent code.
- No Account Needed: Users can start chatting directly on the web or mobile without registration, simple to operate.
- File Upload and Analysis: Supports uploading documents for automatic summarization, analysis, and translation.
- Multilingual Support: Supports communication in multiple languages including English, French, German, Spanish, and Italian.
- Privacy-Friendly Search: Offers the option to enable privacy-protected web search for up-to-date information.
- Cross-Device Syncing: After logging into a Proton account, encrypted chat records can be synchronized across multiple devices.
- Lumo Plus Advanced Features: Unlock unlimited chats, extended chat history length, and larger file uploads.
Usage Help
Getting Started with Lumo
Lumo is simple to use with no complicated setup. The guide is as follows:
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Access Lumo
- Open a browser and visit
https://lumo.proton.me/, or search for “Lumo by Proton” in the App Store or Google Play to download the mobile app. - No registration needed; just type your questions or commands into the chat box on the web and press “Enter” or click “Send” to start chatting.
- To save chat history or use more features, it is recommended to register and log in to a Proton account, where chat records are saved encrypted and only accessible by the user.
- Open a browser and visit
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Core Feature Operations
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Privacy-Protected Chat
- Enter any question such as “How to stay hydrated in summer” or “Help me write an email,” and Lumo will generate a response.
- Conversations are protected by zero-access encryption; the server does not store history.
- When logged in, chat records are encrypted and synced across devices.
- Operation steps:
- Type your question into the chat box and send it.
- View the reply and continue asking to keep the conversation going.
- To clear chat history, on mobile, tap the top-right menu and select “Clear History.”
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File Upload and Analysis
- Users can upload documents for Lumo to summarize or translate.
- Steps:
- Log in with a Proton account (free or Plus plan).
- Click the upload icon next to the chat box and select local files or Proton Drive files.
- Enter commands like “Summarize this document” or “Translate to French.”
- Lumo analyzes the file and returns the result. File size is limited on the free plan; Plus plan supports larger files.
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Enable Privacy-Friendly Search
- By default, Lumo relies only on built-in knowledge. When enabled, it supports web searches for real-time information.
- Operations:
- After asking a question, click the search toggle next to the chat box on the web, or enable it in settings on mobile.
- Lumo uses privacy engines (such as Brave Search) to retrieve information and respond.
- If the result is inaccurate, adjust the question and try again.
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Multilingual Conversation
- Supports multiple languages including English, French, etc., responding in the language inputted.
- Example: “Comment rester hydraté en été?” (French)
- No manual language switching needed; Lumo automatically detects.
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Lumo Plus Upgrade
- For unlimited chats or larger file support, subscribe to Lumo Plus ($12.99/month or $119.88/year).
- Process:
- Log into a Proton account, click “Upgrade” on the web or app.
- Select Lumo Plus and complete payment to unlock advanced features.
- Plus users can save longer encrypted chat histories and upload bigger files for analysis.
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Mobile Usage
- After downloading the mobile app, start chatting immediately.
- Supports voice input: click the microphone icon to speak, Lumo transcribes and replies automatically.
- When logged in, chat records sync between phone and web.
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Privacy Settings
- Ghost Mode: When enabled on mobile, chat records are not saved, suitable for temporary conversations.
- Clear Chat History: Users can manually delete local encrypted history on web or mobile.
Notes
- The free version limits about 100 queries per week.
- File uploads require logging in; free version limits to small files, Plus supports large files.
- Web search must be enabled manually; response speed may be affected by network conditions.
Use Cases
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Personal Privacy Protection Users handling sensitive information such as health or legal consultations can rely on Lumo to secure conversations. Zero-access encryption and no-log policies ensure information confidentiality. Example: input “Summarize contract” or “Explain medical report,” with content accessible only on the user’s device.
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Work Efficiency Improvement Professionals can quickly summarize documents, translate, or generate emails. Example: upload a report and enter “Summarize key points,” or request “Write a Python code snippet,” saving time and effort.
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Multilingual Communication Suitable for multinational teams or travelers, supporting multilingual Q&A. Example: “Wie plane ich eine Reise nach Berlin?” (German), Lumo provides detailed advice.
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Learning and Research Students and researchers can use Lumo to answer academic questions or analyze materials. Example: enter “Explain the basics of quantum mechanics” for a concise explanation. Enabling web search provides the latest information.
QA
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How does Lumo protect my privacy? It uses zero-access encryption to store chat content that only the device can decrypt. Servers do not save records, user data is not used to train AI models, and all services run in Proton-controlled European data centers with no external sharing.
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Do I need an account to use Lumo? No. You can access
https://lumo.proton.me/or use the app to chat without registration. Logging in saves encrypted chat history and unlocks additional features. -
Which languages does Lumo support? Currently supports English, French, German, Spanish, and Italian, with plans to expand. Users can ask questions in any supported language, and Lumo will respond in kind.
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How is Lumo different from ChatGPT? Lumo focuses on privacy protection, does not keep chat logs, does not use user data for model training, uses open-source models, and has transparent code. ChatGPT may save conversations and use them for training, providing weaker privacy.
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What additional features does Lumo Plus offer? The $12.99/month Plus version supports unlimited chats, longer encrypted history, larger file uploads, and multi-file analysis, suitable for heavy users.
