Lumo

What it does

Lumo is a chat assistant that takes typed prompts, including optional web search and uploaded files, and returns text responses. It can also create and edit images, summarize documents, translate text, help with writing and code, and answer general questions. Conversations started while signed in are stored with zero-access encryption, which the vendor says means Proton cannot read them.

People use Lumo for everyday research, brainstorming, drafting, summarizing sensitive documents, and planning tasks. The vendor states that chats are not used to train AI models and that Lumo's code is open source. Lumo can also link files and folders from Proton Drive as context for ongoing work.

A free tier is available with a Proton Account or as limited guest access, and a Plus plan adds more usage. Lumo for Business is offered for teams. The vendor notes that responses can be inaccurate, especially on recent events or highly specific queries, so outputs should be verified before external use.

What it can do

• Answer general questions with optional web search for current information
• Create, edit, and analyze images
• Summarize uploaded documents, including sensitive legal files
• Translate text and improve writing for grammar, spelling, and style
• Help with coding, debugging, and math problems
• Link files and folders from Proton Drive as context for work

Works with

• Proton Drive (linking files and folders as context)

Before you choose

• Responses can be inaccurate, especially for recent events or highly specific queries; verify before using outside Lumo.
• Chats are only saved and searchable when signed in with a Proton Account; guest chats are not saved.
• Free plan has limited usage, and chats are saved for 7 days only; paid plans have much higher limits.

Listed under

• Productivity
• General assistants

Get started

Start a chat without an account as guest, or sign up for a Proton Account to save encrypted chat history.

1. Open lumo.proton.me in a web browser or download the Lumo app for iOS or Android.
2. Type a prompt in the chat window and press Enter or click Send.
3. Optionally sign in with a Proton Account to save and search chats, or create a Free account for more features.

Lumo AI Plus is listed at $9.99/month, billed at $119.88 every 12 months, with a $12.99 monthly rate shown struck through and a 30-day money-back guarantee. Currency options CHF, EUR and USD are shown. Lumo for Business pricing must be confirmed with the vendor.

Source: proton.me/lumo/pricing, checked 29 Oct 2026. Prices can change; check before you buy.

Sources for this overview

Product pages, documentation, and pricing checked 29 Oct 2026. Each source supports part of the overview; availability and prices can change.

• About Lumo, the privacy-first AI assistant | Proton ↗proton.me
• Getting started with Lumo | Proton ↗proton.me
• Lumo pricing and plans | Proton ↗proton.me
• About Lumo, the privacy-first AI assistant | Proton ↗lumo.proton.me
• Create and collaborate with secure online documents | Proton ↗proton.me

Company website

proton.me: product, pricing and policy pages

Web search

Confirms the official site

Social accounts

Accounts the company links, and its posts on X

Human review

Checked by a person

knowledge_base

manual_review

Last checked 29 Oct 2026. Every field keeps its source and date; unknown means we couldn’t confirm it.