ChatGPT vs Lumo

ChatGPT

• General-purpose help with writing, questions and brainstorming
• People who want chat, voice, images and web search in one assistant
• Trying an AI assistant at no cost before paying

Lumo

• People who want an assistant that cannot read or reuse their chats
• Proton users who already keep files in Proton Drive
• Trying a private assistant without creating an account

ChatGPT

• Pro is sold at three price points, $100, $200 or $500 per month, well above the $20 Plus plan.
• Business requires at least 2 users. SCIM, EKM and role-based access control are reserved for Enterprise and Edu.
• OpenAI began testing ads in the free version for logged-in adult US users in January 2026, according to Wikipedia.
• OpenAI's pricing page says the Go plan may include ads.

Lumo

• The free plan limits Max model usage, messages, chat history, image generations and uploads, and allows 1 Project; Proton gives no exact numbers.
• The download menu lists iOS and Android apps and a web app; no desktop app is listed.
• Business use is sold separately, as Lumo Professional or as part of Proton Workspace.

ChatGPT

Conversational help

Answers questions, drafts and reworks text, explains topics and reads uploaded photos in a chat, with history synced across your devices.

Image generation

Creates original images from a description, or transforms existing images from a short instruction.

Advanced Voice Mode

Hold a real-time spoken conversation in the mobile app by tapping the soundwave icon.

Search and Deep Research

ChatGPT Search draws on the web for more up-to-date answers, and Deep Research generates a report from extensive web searches.

Codex

A coding agent that runs on the web, in a CLI, in an IDE extension and on iOS from the Plus plan, with integrations such as automatic code review and Slack.

GPTs and agents

GPTs customize ChatGPT's behavior for a specific use case, and ChatGPT agent carries out multi-step tasks.

Lumo

Zero-access encrypted chats

Conversations are stored with zero-access encryption so that only you can read them; Proton says it cannot access them.

No training on your chats

Proton states that conversations are never used to train AI models, to target ads or to build a personal profile.

Web search

Built-in web search brings real-time information into answers. It is included in the free plan.

Files and Proton Drive

Link files and folders from Proton Drive to give Lumo context. The free plan uploads individual small files; Plus allows multiple large files.

Image generation

Turns a description into an image and lets you refine it through follow-up prompts.

Open-source code

Lumo's code is published as open source, which Proton says lets anyone verify that it is private and secure.

ChatGPT

• Free$0

  Unlimited text chats, with limits on uploads, image creation, voice chats, deep research and memory.

• Go$8

  per month

  More messages with tools, more uploads, image creation and voice chats than Free, and longer memory. OpenAI notes this plan may include ads.

• Plus$20

  per month

  Advanced reasoning models, expanded deep research and memory, plus projects, scheduled tasks and custom GPTs.

• Business$20

  per user / month, billed annually

  For 2 or more users: a dedicated workspace with admin controls, SAML SSO and MFA. $25 per user / month when billed monthly.

• ProFrom $100

  per month

  A choice of three usage tiers at $100, $200 or $500 per month, with the highest limits, pro reasoning and an always-on agent.

• Enterprise & EduCustom

  Sold through sales, with priority request processing, SCIM, EKM, user analytics, domain verification and role-based access control.

Lumo

• Free$0

  Limited Max model usage, messages, chat history and image generations, with 1 Project. No credit card required.

• Lumo AI Plus$9.99

  per month, billed yearly ($119.88); $12.99 billed monthly

  More Max model usage, messages, chat history and image generations, unlimited Projects and Custom Lumos, with a 30-day money-back guarantee.

ChatGPT

• Annual discount

  Business is cheaper when billed annually

  OpenAI's pricing page lists Business at $20 per user / month when billed annually, against $25 per user / month when billed monthly.

Lumo

• Annual discount

  23% off with yearly billing

  Proton's pricing page lists Lumo AI Plus at $9.99 a month when billed yearly ($119.88 every 12 months) against $12.99 billed monthly, labeled as 23% off.