Scamby
Scamby
The usual way to find out whether a dating-profile picture is stolen is to upload it to a reverse-image search — which means giving a stranger's photograph, and the fact that you are suspicious of it, to a company whose business is keeping both. Scamby uploads nothing. It reduces the picture to a 64-bit fingerprint on your device and sends only that.
A fingerprint is eight bytes. You cannot reconstruct a face from it. The picture stays on your device, any text found in it stays on your device, and there is no account to create — so there is nothing tying a check to you.
Scamby is being built in the open. The fingerprinting, the matching, the on-device text reading and the lookup service are written and tested, and the app runs — but the shared database it checks against holds 28 fingerprints built from 14 reported screenshots, so it recognises almost nothing. When there is a build worth your time this page will say so. There is no mailing list and nothing here collects your address.
An illustration of a result, not a screenshot. Only the fingerprint above was sent; the text was read and kept locally.
An image you import is shrunk to a 32×32 grey grid, run through a discrete cosine transform, and squeezed into 64 bits — a perceptual hash. Two images are compared by counting how many of those bits differ. The same photograph re-saved, resized, screenshotted or turned grey lands within a few bits of itself. Two unrelated photographs differ by about thirty.
That gap is what makes the check possible without the picture. Scamby sends the fingerprint to a server that holds a database of fingerprints — not pictures — and gets back whether anything is close. The server never sees your image, never sees text found in it, and has no account or device identifier to attach the request to.
Re-compression, resizing, a screenshot, a greyscale filter — all produce a fingerprint within a few bits of the original. A horizontal flip would defeat it entirely, so every image is checked both ways round, and a match that only appears flipped says so.
Scamby is in the iOS share sheet, so a profile screenshot goes straight from Photos or a message into a check. The extension holds no shared storage with the app — it fingerprints, answers, and keeps nothing.
A handle, a number, a watermark burned into the corner — Apple's own text recognition reads it on your device, in 33 languages, and keeps it on your device. It is never sent for matching, because the text is the part that could identify a person. A few well-known patterns — a request for money, the stranded-abroad story — are matched against it on your device too, and shown with the words that matched so you can judge them yourself.
A result is a bit distance and a band: identical, almost certainly, or possibly. Never a percentage. A bit distance is not a probability, and “87 % likely fake” would be a lie about how much Scamby knows.
A match shows where the reference image was reported. “Flagged” with nothing behind it is an accusation rather than information, and the app will not make one.
Four things are built into the app rather than pledged by it. Each one fails the build if it stops being true.
The honest version, because the comfortable version would be a lie by omission. The server receives your fingerprints and the IP address that any connection carries. It is built to keep neither: there is no access log, no record of lookups, no counters, and a database with nowhere to put them.
But notice the difference in kind. The four points above are things you can check in the source and that the build refuses to break. The server's behaviour is a promise about software running on someone else's computer. It is open and auditable, and it is still a weaker assurance — anyone who tells you those are the same thing is overselling it.
This site matches the app: no analytics, no cookies, no forms, and no JavaScript of ours. The privacy policy says all of this at length.
Scamby recognises the same image, edited. It is worth being precise about what that excludes, because the gap between what a tool like this does and what people assume it does is where the harm is.
How far an edit moves the fingerprint, out of 64 bits. Scamby reports a match at 10 bits or fewer. These are measured, not estimated, and the benchmark that produces them is in the repository.
| What was done to the image | Bits changed |
|---|---|
| Re-saved as JPEG, any quality | 0–6 |
| Resized, anywhere from 160 px to 1200 px | 0–2 |
| Screenshotted — resized and re-saved | 0–4 |
| Converted to greyscale | 0 |
| Brightened by a quarter | 2–8 |
| Cropped by 5 % | 9–16 |
| Given a thick white border | 22–31 |
| Flipped horizontally — so both ways are checked | ~32 |
| An entirely different photograph | 16 at the very nearest, 30 typically |
The three marked rows are the limits above, in numbers. Flipping is handled by checking the image both ways round; cropping and borders are not handled yet, and the page will change when they are.
Scamby Plus — $4.99 a year. One auto-renewing subscription, cancellable any time from your Apple Account settings. No trial that bills you quietly, no monthly tier that costs more over a year, and no free tier that pays for itself with your data.
The subscription is what pays for the shared database and the server that answers lookups. It is verified on your device against Apple's own receipt — Scamby's server is never told anything about your Apple Account, which is also why there is no account to create here.
United States, English, on iPhone, iPad and Mac.