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Is FBA Calculator for Amazon FBA Sellers - Free safe?

Low risk

FBA Calculator for Amazon FBA Sellers accepts a login API key from any postMessage sender on Amazon pages, with no origin check.

After you click the extension's login button, its content script installs a window.onmessage handler on every open Amazon tab that accepts a marketgap.pro API key from any message starting with a fixed prefix, without checking who sent it. That key is stored and reused as the Authorization value on all later requests to marketgap.pro, so a page that can reach the same window object can substitute its own key and redirect your product-research data (viewed ASINs, Amazon site) to an account it controls.

Part of this rating comes from analysis signals we haven't published as detailed findings yet.

MarketGapv2.7Chrome Web Store
17Risk
Who publishes it

Market Gap LLC - no other listings under this identity, 3 shared hostnames

What this publisher told the store about itself, and the other listings that told it the same thing.

Publisher
MarketGap
Declared legal entity
Market Gap LLC

Shared hosts - 3 hostnames

Hostnames hardcoded in this extension that few other listings call. That can mean one operator behind both, and it can equally mean a small shared vendor, so it is context rather than a conclusion. Hosts that many listings call are left out: they are services, not connections.

blissfuljs.com
Also called by 1 other listing: CAVA
webveteran.com
Also called by 2 other listings, including CAVA
jspanel.de
Also called by 4 other listings, including CAVA

AI-generated. Findings may contain errors. Those marked Verified have been manually reviewed.

Publishers can request a review.

What it can do

Permissions this extension asks for, as declared in version 2.7. Asking for a permission is not a finding on its own - it is what the extension can do if it chooses to.

  • Read and change your data on amazon.com

    *://*.amazon.com/*

  • Read and change your data on amazon.ca

    *://*.amazon.ca/*

  • Read and change your data on amazon.co.uk

    *://*.amazon.co.uk/*

  • Read and change your data on amazon.fr

    *://*.amazon.fr/*

  • Read and change your data on amazon.de

    *://*.amazon.de/*

  • Read and change your data on amazon.es

    *://*.amazon.es/*

  • Read and change your data on amazon.it

    *://*.amazon.it/*

  • Read and change your data on marketgap.pro

    *://marketgap.pro/*

  • Store data in your browser

    storage

  • Store an unlimited amount of data in your browser

    unlimitedStorage

  • Read and change cookies, including the ones that keep you signed in

    cookies

Where it sends data

Destinations our analysis observed FBA Calculator for Amazon FBA Sellers - Free contacting. Sending data somewhere is not a finding on its own - an extension that syncs your settings has to talk to its own server - but it is where your data can go, and who else it goes to.

  • marketgap.pro

    FBA Calculator for Amazon FBA Sellers - Free sends data to marketgap.pro. No other extension we have analyzed sends data here.

Updated 30 September 2026epldhpeodjhhfkoeojibnfjibgiihdpp