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Persistent Memory for ChatGPT: One Vault, Both Assistants

John Rood··4 min read

ChatGPT's built-in memory works. It summarizes what it learns and carries context between conversations. If that covers how you work, keep it on.

The case for owning something separate is narrower and stronger: the decisions you save on purpose, with the reasoning attached, in a place that outlives any single app. That context lives in one assistant today. It is the wrong place the moment you open another one.

You settle something in ChatGPT, switch to Claude for a longer draft, and spend the first few messages rebuilding the brief. The decision exists. It just lives in the wrong room.

Two systems, one portable

The built-in system serves the assistant that has it. A MemoryRouter vault serves you: save once, and the same context is available to ChatGPT, Claude, Cowork, Claude Code, Codex, and the other supported clients you connect.

They coexist. Connecting MemoryRouter does not read, import, or replace ChatGPT's built-in memory, and there is nothing to delete to make room. Routine messages are not silently captured either; ChatGPT decides when the tools run, so ask in plain language and read the tool result when it appears.

Set it up in Developer mode

MemoryRouter connects as a remote MCP server through Developer mode. Eligible plans are Plus, Pro, Business, Enterprise, and Education on ChatGPT web. Managed workspaces can still block Developer mode, so if the option is missing, the plan and workspace policy are the first things to check.

  1. Turn on Developer mode in ChatGPT settings.
  2. Open ChatGPT Plugins, create a developer-mode app, and paste this address: https://mcp.memoryrouter.ai/mcp
  3. Complete MemoryRouter OAuth and pick exactly one vault. Authentication runs in the browser, not through a key.
  4. Start a new conversation, choose Developer mode from the plus menu, and add MemoryRouter.

The documentation walks through every step and lists the tools you will see.

Save one decision on purpose

Watch the path work on something harmless first:

"Store this in MemoryRouter: the demo newsletter's working title is Cedar Finch 27."

Approve the write when ChatGPT asks. Then make it a habit with real work, one line at the end of a session:

"Save to MemoryRouter: the launch post goes out Tuesday because weekend traffic on this list runs at half the weekday rate."

The part you are really saving is the why. Final documents rarely carry it, and it is exactly what you want in three weeks when the topic comes back in a different tool.

Open Claude and paste nothing

Connect Claude to the same vault through its custom connector, then open a fresh conversation and ask:

"Search MemoryRouter for the demo newsletter's working title."

Claude answers with Cedar Finch 27. The fact was saved once and read from two assistants, with nothing copied between the apps and nothing pasted into the new conversation. If a search comes back empty, ask for memory status and confirm the connection is pointed at the vault that holds the save. The Claude side has its own setup, covered on the Claude MCP memory page.

What ChatGPT already knows

One more move, worth doing a single time: bring the memory ChatGPT currently holds into the vault. Ask it to draft the list of what it can see about you, correct anything stale, approve the version you want kept, and have it save only that. Two minutes of review turns context that was locked inside one app into context every connected tool can use. The exact prompts are in the transfer walkthrough.

The boundaries

  • This is a Developer mode connection. MemoryRouter is not in the public Plugins Directory, so there is nothing to install from a store.
  • Old conversations do not come along. The connection handles new saves and searches; bringing in history is a separate workflow.
  • One vault per connection, chosen at sign-in, and the model cannot switch vaults mid-conversation. To point at another vault, disconnect and reconnect.
  • Deletion is deliberate: clearing a whole vault requires typing the exact phrase DELETE ALL MEMORIES, and single memories can be removed from the dashboard.

The ChatGPT page covers the connection and the transfer prompts end to end.

Create your MemoryRouter account, connect ChatGPT, and save the next decision somewhere both assistants can reach it.

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