Substrate Memory privacy policy

In short

• The extension reads nothing until you agree to how it works and turn a site on, or right-click selected text. Nothing is sent until you sign in.
• It forms memories on your computer. The full page text never leaves it.
• It sends only memories you don't untick, with the title and domain of the page each came from. Never the page's address.
• Memories are private to your account and are not used to train AI.
• It has no analytics, tracking or remote code. We never sell your data.
• Links from the extension to our site carry a tag saying they came from the extension, and nothing about you.

1. What the extension reads

• On sites you turn on: the visible text of each page you open there, automatically as you use the site. On ChatGPT, Claude and Gemini, that's the conversation on the page, including your own messages. Each site needs its own Chrome permission, which you grant and can revoke.
• When you use “Remember in Substrate”: the text you selected, plus the title and address of that tab, for that one click.

It never reads:

• password fields, payment fields, or text you are still typing;
• other tabs, browsing history or cookies;
• incognito windows (the extension is blocked there);
• known banking, payment, health, email, private messaging, password manager or Google account sites, sign-in and payment pages, or any URL that carries a sign-in token, even if you turn the site on. You can block more sites yourself.

It takes no screenshots and records no keystrokes.

2. What happens on your computer

• Redaction. Before anything is stored, the extension removes API keys and tokens, private keys, passwords written in text, card numbers, IBANs and links that carry credentials. It also removes email addresses and phone numbers unless you turn that off in Settings. It runs again on each formed memory, and on the page title before it is sent. Redaction works by pattern, so it can miss something, and it doesn't remove names or other details. That's why memories wait in the side panel, where you can edit or untick them.
• Forming memories. Chrome's built-in Gemini Nano model turns page text into short memories, on your computer. If your computer can't run it, simple rules do the same job, also on your computer. Page text is held in memory only while a memory is formed, then discarded.
• Stored locally (chrome.storage.local): memories waiting in the side panel, a list of the last 200 sent memories, your settings and site list, your Substrate sign-in tokens, and the addresses and short fingerprints of up to 500 recently captured pages, so the same page isn't turned into memories twice.

3. What is sent to Substrate

Only memories you don't untick. Each one contains:

• the memory text (up to 600 characters), as it stood in the side panel, including your edits;
• the title and domain of the page it came from (the title also as a label);
• a random ID, so a retry doesn't save it twice;
• whether the memory is short-lived.

Your first 5 memories wait for your OK. So do memories from sites you added yourself, and memories formed before you signed in. Others are sent when the wait you chose ends, even if you never open the side panel, or when you press Send. The wait is 10 minutes by default. You can also pick 1 minute, 1 hour, right away, or only when you approve. If you untick a memory, it is deleted from your computer and never sent. Memories go over HTTPS to app.trysubstrate.co, using a sign-in token for your account. They go nowhere else.

4. What we do with it

We use memories only to provide Substrate to you: we store them in your account so the AI agents you connect can recall them. We do not use extension data for advertising, do not sell it, and do not use it to train AI models. Our staff do not read it except to provide support you ask for, when necessary for security, or when law requires it.

5. Limited Use

6. Sharing

Memories are private to your Substrate account. Only you and the AI agents you connect can recall them. They don't appear on your Wiki pages, and sharing a page doesn't share them. We disclose data to service providers and as required by law, as described in the Substrate Privacy Notice.

7. Your controls

• Turn any site off, or revoke it in Chrome's extension settings.
• Pause for an hour, until tomorrow, or until you turn it back on. Nothing is read automatically or sent while paused.
• Untick or edit any memory before it is sent, or choose to send only when you approve.
• Forget a sent memory from the Sent tab. Your agents stop recalling it.
• “Delete all local data” clears everything the extension stored. Uninstalling does the same.
• Sign out to remove your tokens from Chrome.
• To ask us to delete data in your account, email pavel@trysubstrate.co.

8. Retention

Data on your computer stays until you delete it or uninstall. Without sign-in, at most 50 memories wait, and ones older than 7 days are deleted. Signing out removes only your sign-in tokens. The Sent list keeps the last 200 entries.

Memories in your account are kept for the life of the account. Forget is not deletion: the memory and a record of the change are kept for audit. Account deletion is covered in Section 12 of the Substrate Privacy Notice.

9. Changes

If we change what the extension reads or sends, we'll update this page and the date at the top before the new version is published, and the extension will ask for your agreement again.