Security model
It reads the fields. It does not invent values.
The extension sits beside the checkout, not in front of it. Card fields stay in the browser, and every reported value comes from the gateway’s own response.
Data flow
Three boundaries, each with one owner.
The browser reads the fields
Card number, expiry and CVV come from the checkout fields the customer filled. The extension reads them in place and never routes them anywhere except the relay you configure.
The extension reads the gateway
Status, decline code, charge id, ACS vendor and challenge result are read from the gateway's own responses. No value is computed locally.
The checkout keeps control
The extension completes the challenge step and confirms the intent; it does not hold a merchant balance and does not change the checkout's own pricing.
Controls
Card fields
Browser only
Read from the checkout, never stored remotely.
Gateway values
Verbatim
Status, code and charge id, never paraphrased.
Transport
HTTPS relay
One POST to the endpoint you configure.
State
Extension storage
Last result and trace survive a tab close.
Switches
Storage-backed
Every toggle writes straight to storage.
Removal
One reload
No destructive writes to your checkout.
Subprocessors
Every processor below touches the extension’s flow. Only the relay endpoint receives the card fields, because the extension reads them from the checkout and posts them once a run settles.
| Processor | Role | Region |
|---|---|---|
| Chrome | Extension host and storage | Local browser |
| Relay endpoint | Receives settled card POSTs | Your choice |
| Checkout host | Renders the fields the extension reads | Global |
| Delivery channel | Optional forwarding of posted runs | Global |
Found a vulnerability? Read the disclosure policy before you test anything in production. Privacy policy.
Nothing to migrate
Load it and the checkout keeps working as it did.
Card fields stay in the browser, gateway values stay verbatim, and the extension only posts a settled run to the relay you configure.
- Card fields read in place
- Gateway values verbatim
- State in extension storage
- Reversible in one reload