SecondBrain · Guides · ChatGPT + Claude shared memory
How to share one memory between ChatGPT and Claude
Why your AI assistants do not remember you
Every major assistant now ships some form of memory, but each one is a silo. ChatGPT's memory belongs to your OpenAI account. Claude's memory belongs to your Anthropic account. Gemini keeps its own. None of them can read the others, so you end up re-explaining your projects, preferences and context to every tool, on every device. Switching assistants means starting from zero.
The fix: one external memory over MCP
The Model Context Protocol (MCP) is an open standard, introduced by Anthropic in November 2024 and since adopted across the industry, that lets AI assistants call external tools and data sources. Point several assistants at the same MCP memory server and they all read and write one memory: yours. Tell Claude something once and ChatGPT can recall it, and the other way around.
You can self-host an open-source memory server if you are technical. If you want it to just work, a managed service handles hosting, sign-in and sync. SecondBrain is a managed MCP memory with a twist: the memory is also a voice-first phone app, so most of what your assistants know, you simply said out loud at some point.
Set it up in about two minutes
1. Get SecondBrain and turn on Pro
Download SecondBrain free on iPhone or Android, or open the web app. The shared memory layer is a Pro feature, so enable Pro in the app first.
2. Connect Claude
- In Claude, open Settings → Plugins → "+" → Add marketplace.
- Paste
fed3c3sa/secondbrain-shared-memoryand install the SecondBrain plugin. - Press Connect and sign in with Apple or Google. No keys, no tokens.
In Claude Code, run /plugin marketplace add fed3c3sa/secondbrain-shared-memory, then /plugin install secondbrain@secondbrain, then /mcp to sign in.
3. Connect ChatGPT, Gemini or Cursor
Run npx secondbrain-connect once in a terminal and sign in in the browser. The command configures the assistants you use to reach the same memory. The full setup guide lives on GitHub.
What actually gets shared
| What you save | How it gets in | Who can recall it |
|---|---|---|
| Notes and facts | Speak or type in the app, or ask any connected assistant to remember | Every connected assistant, plus the app |
| Calendar events | Created automatically while you talk, or by an assistant | The app's calendar, with two-way iPhone Calendar sync |
| Reminders and follow-ups | Detected in your voice notes, or set by an assistant | The app, plus any assistant that asks |
| Preferences and context | Saved once in any assistant | Every other assistant, so you stop repeating yourself |
Other ways to do it
Being fair about the alternatives:
- Self-hosted MCP memory servers such as Basic Memory or OpenMemory by Mem0 are free and open source. You run and maintain them yourself, and capture is typing-first. A good fit for developers; see the plain-English guide to MCP memory servers.
- Browser extensions that sync chat memory across AI websites exist as well. They live in the browser, so they do not help in native apps, in coding tools, or from your phone.
- A pasted context file (a personal readme you paste into each new chat) is free and simple, but manual: it goes stale, and nothing you say on the go ever reaches it.
Questions people ask
Can ChatGPT and Claude share memory natively?
No. ChatGPT's memory lives in your OpenAI account and Claude's memory lives in your Anthropic account, and neither can read the other. The only way to share one memory between them is an external memory both can reach, which is what an MCP memory service provides.
Do I need an API key to set this up?
Not with SecondBrain. You sign in once with Apple or Google, both in the Claude plugin and in the npx secondbrain-connect setup for ChatGPT, Gemini and Cursor. There are no API keys to create, copy or rotate.
Does the shared memory work from my phone?
Yes. SecondBrain is an iPhone and Android app, so you capture by voice on your phone and the memory is available to Claude, ChatGPT, Gemini, Cursor and Claude Code on your computer. A fact you speak on the go is recalled in any connected assistant.
Is it safe to give AI assistants access to a memory server?
Scope matters. SecondBrain's MCP server only exposes your own memory, isolated per account, with revocable tokens. Data is stored in the European Union on Supabase, is never used to train models, and can be deleted entirely from the app at any time. Assistants see only what the memory tools return, not your account.
Stop repeating yourself
One memory for ChatGPT, Claude, Gemini, Cursor and Claude Code. Free to start.