Why no single site can "do" reverse image search for you
Reverse image search means searching by a picture instead of by text - finding every other place an image appears online, tracking down the original source of a photo, or identifying what is actually in it. Doing that requires matching your image against a visual index with billions of entries, and only a handful of companies (Google, Microsoft, Yandex, TinEye) have built one. No independent tool can replicate that index, so anyone offering to "reverse search" your image on their own servers is either quietly redirecting you to one of those engines anyway or not really searching at all.
What this tool does instead
It previews your chosen image locally, in your browser, so you can confirm it's the right file before you go anywhere - then gives you one-click links straight to the upload page of each major reverse-image engine. Nothing is uploaded to this site at any point; the preview uses the browser's own FileReader API, which never leaves your device.
Picking the right engine for the job
The four engines are not interchangeable. Google Images has the broadest general-purpose index and is the best first stop for most photos. Bing Visual Search leans toward shopping and product matches. Yandex Images has a reputation for being unusually good at tracing the original source of a photo of a person, likely due to its indexing focus. TinEye is purpose-built for exact and near-exact match tracking, and shows you the earliest date it has seen a given image indexed - useful for proving where a photo first appeared.
Common uses
People use reverse image search to check whether their own photos are being used without permission, verify whether a profile picture or product photo is stolen or stock, find a higher-resolution version of an image, or identify a location, plant, or object from a picture.