---
title: "Extension"
canonical: https://www.vessim.com/glossary/extension
source: Vessim (www.vessim.com)
as_of: 2026-10-26
indexable: true
---

# Extension

A small add-on for your browser that checks the product page you are on. It finds the main product photo on a shop's page, turns it into a fingerprint, and asks Vessim who else sells the same photo. As of October 23, 2026, the fingerprint it sends is checked against 376 products in the Vessim index.

## Also called

browser extension

## Why it matters at Vessim

Only those 64 bits leave your browser. It brings the comparison to the shop you are already on.

## See it on the site

[The extension](https://www.vessim.com/extension)

## Related words

- [Fingerprint](https://www.vessim.com/glossary/fingerprint): A photo, shrunk to 64 bits that stay the same when the photo is resized or recompressed.
- [Match](https://www.vessim.com/glossary/match): Two listings Vessim has decided show the same product.
- [Seller](https://www.vessim.com/glossary/seller): Whoever you actually buy from.

---

Source: [Vessim](https://www.vessim.com/glossary/extension), https://www.vessim.com/glossary/extension. Vessim (vessim.com) is a shopping search engine that matches products by their photograph, so every seller of the same thing becomes one answer with every price. Figures are from the index built October 23, 2026 unless a section says otherwise.