Fill fields. Not the AI's context.
SecureFill lets an assistant fill form fields by passing a single opaque reference. The extension resolves the values itself and writes them into the page — so they never enter the assistant's reasoning, logs, or tool calls.
How it works.
Four steps, and the value never touches the assistant.
Pass a reference
The assistant asks SecureFill to fill a set of fields by passing a single opaque reference — never the values themselves.
Resolve out of context
The extension's service worker resolves the reference against your configured backend (or decrypts a locally held source) — entirely outside the page the assistant sees.
Fill the right frame
Each value is routed only to the frame that needs it — including cross-origin embedded frames — and written with framework-compatible events.
Return only a status
The assistant receives a fill status and nothing more. Resolved values are cleared from memory after the fill.
What it guarantees — and what it doesn't.
Straight about the security boundary, so you know exactly what you're relying on.
Strong for cross-origin embedded fields
Sensitive fields commonly render inside cross-origin embedded frames. Page JavaScript — where the assistant runs — cannot read across that origin boundary, so values filled there stay out of the assistant's reach. This is the primary case.
Weaker for same-origin fields
If a field lives in the top page, page JavaScript can read its value after the fill. The isolated world keeps the credential, the key, and the resolution logic out of the page — but it cannot hide a value already typed into a same-origin input.
Fills require an approved reference
A fill request carries only an opaque reference, resolved against an authenticated, single-use, approval-gated endpoint. A malicious page cannot extract data by faking a fill request — it has no valid reference.
Memory wipe is best-effort
Resolved values are overwritten and dropped after the fill, but JavaScript gives no hard zeroization guarantee. Values are short-lived but not provably erased.
Get started
Three steps from install to first fill.