The best note-taking apps for ChatGPT, Claude, Le Chat, and Grok in 2026

A year ago, a notes app and an AI chat were two separate things. You asked ChatGPT, then copied the useful part somewhere, or more often, you did not.

Now the notes apps people actually use can connect to the assistants they already pay for: ChatGPT, Claude, Le Chat, and Grok. That changes what to look for. The question is no longer only "is it a good place to write?" but also "can my AI read it, write to it, and keep what I learn?"

This guide compares three apps on that question. We make Capacities, one of the apps on this list. It is not first, every app gets the same parts, and we say where each one falls short, including ours. How we made this list explains the rest.

The short answer

What to look for

An official connector. Most apps connect through MCP, the Model Context Protocol, an open standard that ChatGPT, Claude, Le Chat, and Grok support. An official connector, run by the app's maker, is easier to set up and more likely to keep working than a community one.

Read and write. Reading lets your AI answer from your notes. Writing lets it save what you learn. Some connections only read. ChatGPT's own built-in apps, for example, are search-only.

Structure the AI can understand. An AI finds and fills notes better when they have clear titles, types, and properties. "The books I finished this year" is easy when books are a type with a status. It is guesswork in a folder of loose pages.

A place you want to be yourself. An AI second brain still needs a person who reads it, prunes it, and adds to it. If you do not enjoy opening the app, the knowledge goes stale.

Where your data lives. A connected AI reads your notes through its own servers. Check the AI app's data settings, and check where the notes app stores your data.

The apps

Notion

Best for: teams whose knowledge already lives in Notion, and who want AI agents that work across it.

Notion is the all-in-one workspace most people know: pages, databases, wikis, and projects. Its AI story is built for teams. The AI page leads with "Meet your 24/7 AI team", and the pricing page with "One tool to run your company."

How your AI connects: Notion runs an official remote MCP server. Its help page documents connecting Claude and ChatGPT to a Notion workspace. ChatGPT also has a built-in Notion app, which can search and read pages but not write.

Built-in AI: Notion Agent, AI Meeting Notes, and Enterprise Search are on the Business plan. Free and Plus get a limited trial. Custom Agents cost extra credits, at $10 per 1,000.

Where it falls short for personal use: you design the databases before the AI has anything clean to work with. Some connector tools, such as advanced search filters, need Business or Enterprise. Developers report that the connector uses a lot of the context window. One r/ClaudeAI user wrote: "Usually could only get through 3-4 tool calls before it would stop connecting at all." Notion's own help page advises to "Start with single-player use cases."

• Price: free plan. Plus is $10 per member a month, Business $20, billed annually.
• Where your data lives: US. EU data residency on Enterprise only.
• Compare: Capacities vs Notion, and Notion alternatives.

Capacities

Best for: your own notes, research, and meetings, in one place that every assistant you use can read and write.

Capacities is a notes app built around objects. Every note has a type, such as a page, a person, a book, or a meeting, with properties that fit it. Links go both ways, and a daily note catches anything you have not sorted yet.

How your AI connects: an official connector, made by Capacities. It is in ChatGPT's plugin directory and Claude's connector directory. Le Chat (Mistral) and Grok connect the same way, as custom connectors, and Claude Code uses the same connection from the terminal.

What your AI can do there: search, list by type, tag, or collection, read whole notes with their properties, create pages, tasks, and objects of any type, edit properties and paragraphs, delete objects, save to today's note, and upload files. Edits are saved in version history.

Built-in AI: an AI chat inside the app on Pro, with models from OpenAI, Anthropic, Google, xAI, Mistral, and others, and your notes as context. Pro+ adds a larger monthly budget. Chats in ChatGPT, Claude, Le Chat, or Grok do not use that budget.

Where it falls short: a connected AI cannot create object types or properties. Broad "read everything" prompts work poorly, so you search or list first. There is no team plan and no real-time collaboration. It is a cloud app, not local files, and it is not end-to-end encrypted.

• Price: free plan with unlimited objects. Connecting an assistant needs Pro. See pricing.
• Where your data lives: EU servers. Capacities Labs GmbH, Freiburg, Germany.
• Guides: connect ChatGPT, connect Claude, a second brain for AI agents.

Obsidian

Best for: people who want their notes as plain Markdown files, and whose AI is a coding agent such as Claude Code.

Obsidian is a free editor for a folder of Markdown files. The most popular setup of this kind is an Obsidian vault with Claude Code running in it, a CLAUDE.md file that explains the conventions, and Git for history.

How your AI connects: coding agents read and write the files directly. Obsidian added an official command-line tool in version 1.12 in February 2026, which needs the desktop app running. There is no official MCP server. Community plugins add one. Le Chat and Grok on the web cannot see a vault on your computer.

Built-in AI: none from Obsidian. Community plugins add chat with many providers.

Where it falls short: ChatGPT, Claude, Le Chat, and Grok on your phone cannot reach the vault without extra setup. You maintain the structure yourself, in folders and front matter, and agents have to follow your rules. People running it describe "a mess of outdated facts" when nobody prunes.

• Price: free. Sync is $4 a month billed annually.
• Where your data lives: on your device.
• Compare: Capacities vs Obsidian.

Comparison table

Why Notion is the default, and when it is not

For many people, Notion is the first answer to "where should my AI knowledge live?" It is everywhere, it has an official connector, and its AI is strong.

It is also built for companies. The full AI is on the Business plan, priced per member. The connector works best when your workspace is already well organized, and Notion's own advice is to use "descriptive page titles" because "AI apps rely on clear page titles to understand your content structure." For a team with a maintained wiki, that is fine. For one person, it means building and maintaining databases before the AI can help.

A notes app built for one person gets you there with less work. In Capacities, a Book is already a book, with an author and a status, and a meeting already links to its people. There is no database to design first. That structure is what makes an AI useful in your notes, and you get it by writing, not by building.

Who should not use Capacities

• Teams. If you need a shared AI knowledge base with permissions, use Notion.
• People who want their agent to work on files. If Claude Code should grep and rewrite your notes, use Obsidian.
• People who need end-to-end encryption. Capacities encrypts data in transit and at rest. It does not encrypt it end to end.
• People who want the AI to design their structure. A connected AI cannot create object types or properties in Capacities yet.

How we made this list

• We make Capacities. We placed Notion first because it is where most people start. Every app gets the same parts, and every entry says where it falls short.
• Three apps, on purpose. These are the three people actually choose between: the team workspace, the personal notes app, and the folder of files.
• Facts come from official sources, read in October 2026: each app's pricing page, help center, and connector documentation, plus OpenAI's and Anthropic's help pages. Prices are in US dollars. Prices and plan rules change, so check before you buy. Capacities prices are on our pricing page, not in this guide.
• Developer complaints are quoted from public threads, such as this r/ClaudeAI thread on the Notion connector. They are reports, not our benchmarks.
• For Notion and Obsidian, we read the documentation. We have not run their connectors for months, and we say so here.
• If something is wrong or out of date, email [email protected] and we will fix it.