How it works
Sharp puts several shots of the same scene together into one picture. Everything happens in this browser tab, on your device: the photos are read from your disk, merged here, and the result is saved back to your disk. They are never sent anywhere.
Why your photos can’t leave
The page is served with a security policy that lets it talk only to sharpmerge.com, and it never sends your pictures there either: there is nothing on the server to receive them. Once the page has loaded it works with no internet connection at all — try it in flight mode.
Check it yourself
You don’t have to take our word for it. In Chrome or Edge, press F12 (on a Mac, ⌥⌘I) and open the Network tab; in Safari, turn on Settings › Advanced › Show features for web developers first, then Develop › Show Web Inspector › Network; in Firefox, press F12. Choose photos and make a picture: the list shows the page’s own files and the engine (sharp_engine.wasm) being read from this site, and nothing going out with your photos — no upload, no request the size of a photo.
- The only requests the page ever makes of the server are for its own files and, when you unlock Sharp Pro or remove it from this browser,
/api/activatewith the licence key, or/api/deactivatewith that activation’s number — nothing else is sent. - The page’s Content-Security-Policy header (Network › the page › Headers) says
connect-src 'self': the browser itself refuses to let the page talk to any other site. - After a first visit, switch the network off — flight mode, or Network › Offline — and reload: Sharp keeps working, because everything it needs is already on your computer.
What runs
The merging is the same engine as the Sharp app for iPhone and iPad, rewritten to run in the browser (Rust compiled to WebAssembly). It lines the frames up when asked — by comparing small windows of each frame with the middle one, and only moving a frame if that clearly makes it match better — then combines them a band of rows at a time, so even 45-megapixel photos fit in a phone’s memory.
- Focus lines up a focus bracket — shift, the slight change of size as focus moves, and a rolled wrist — then takes every part from the frame that had it sharpest, blended where neighbouring frames share it. You choose the detail size by comparing four on a crop. It keeps the frames on this device’s private storage while it works and removes them after.
- Clean averages every frame: the noise falls with the square root of the number of frames.
- Vanish finds, at every point, what most frames agree on and averages those frames; anything only a few frames saw — a passer-by, a car — is left out. It keeps the frames on this device’s private storage while it works and removes them after.
- Trails keeps the brightest (or darkest) frame at every point, whole pixels, so no colour is invented.
- Blend is exposure fusion: each part of the picture is taken from the frames that exposed it best.
- Pano finds matching points where neighbouring frames overlap, works out how the camera turned, lays the frames on a cylinder (or a plane, for a narrow turn), evens out their brightness and blends the seams; the result is cropped to where every part was photographed, so nothing is filled in.
- Pick scores every frame for detail and hands back the sharpest file untouched.
What you get
A full-resolution JPEG, with no watermark, at the quality you choose — and, if you like, a lossless PNG beside it. When your photos are JPEGs it keeps their colour profile and which way up they go; nothing else about them — camera, place, time — is copied into the result. Compare puts the result over the middle frame, with a line to drag between them.
Limits
Up to 12 photos at a time, all the same size — Sharp Pro for the web (US$15, once) takes as many as your computer can, and adds the retouch brush (paint the right frame back in where the merge guessed wrong), a 16-bit TIFF and PNG, the maps, every frame lined up and batches — split where you paused between bursts, and in Chrome and Edge saved straight into a folder. You can choose a whole folder of photos, or drop one on the page. JPEG works in every browser; HEIC photos open in Safari.
Projects
Each run is kept in this browser as a project: the result, its map and the settings, and each photo’s name, size and date — never the photos. Open one to see and download its result again, or choose the same photos to make it again. With Sharp Pro every run is kept, and a saved retouch can be carried on later. Projects stay on this device until you delete them.
RAW
Camera RAW files — Canon CR2 and CR3, Nikon NEF, Sony ARW, Fujifilm RAF, Olympus ORF, Panasonic RW2, Pentax PEF, DNG including iPhone ProRAW, and most others — are developed here, in every browser, free, by LibRaw. Every frame of a run is developed the same way: the middle frame’s white balance as shot and one brightness, so the frames match and a bracket keeps its stops; a dark scene stays dark. LibRaw can’t read Nikon’s “High Efficiency” NEFs, nor DNGs compressed with JPEG XL (an option on newer iPhones): when such files carry the camera’s own full-size JPEG, as Nikon’s do, the run is made from those JPEGs instead, and the result says so.