Photo Stitcher Online — Free, No Signup

How to do it

Take two to four photos that overlap by roughly a third, in order from left to right or top to bottom.
Drop them onto the upload box together, or click it and select them all (JPG, PNG or WebP, up to 5 MB each).
Choose Panorama for a scene you swept across, or Flat scan for a document, poster or map photographed in pieces.
Click stitch. If the tool reports it cannot find enough overlap, retake with more shared content between frames.
Download the merged image. Crop the uneven edges in any editor if you want a clean rectangle.

How the stitcher finds the join

The tool does not need you to line anything up. It looks for corners — points where the image changes sharply in two directions, like the edge of a window or the tip of a leaf — in each frame, then compares small patches around those corners to find the same points in the neighbouring frame. Most candidate matches are wrong, so it runs a consensus step that tries many small subsets of matches, fits a transform to each, and keeps the one the most other matches agree with. That transform describes how the second frame is shifted, rotated and scaled relative to the first. Once every frame is placed, the overlapping regions are feather-blended so the seam fades from one frame to the next instead of cutting. The whole thing runs in a background thread in your browser.

Shooting frames that stitch cleanly

Overlap is the single biggest factor. Aim for about a third of each frame shared with the next; less than a fifth and the stitcher may not find enough matching points, more than half is wasted. Turn the camera from one spot rather than walking sideways, because a stitch models the frames as a rotation and walking introduces parallax that no similarity transform can undo. Lock exposure if your camera lets you, or at least avoid framing the sun in one shot and shade in the next, because a brightness jump shows at the seam even after blending. Keep the horizon at the same height in every frame. Avoid people or cars crossing the overlap, since a subject that moved between frames appears twice or half-transparent.

Panorama mode versus Flat scan mode

Panorama is for a scene: a landscape, a room, a skyline. It expects the frames to be related by a rotation of the camera and allows some scale change, which handles the way a phone panorama sweep behaves. Flat scan is for a flat object photographed in pieces — a large drawing, a newspaper page, a map, a whiteboard — where the camera moved parallel to the surface. It biases the alignment towards pure translation and is far more forgiving of the low-texture areas that documents have, because a blank margin gives the corner detector nothing to work with. If a document stitch fails in Panorama mode, Flat scan will often succeed on the same frames.

When it refuses, and why that is better

If the stitcher cannot find a confident alignment it says so rather than producing a warped result. The two messages you may see are that it could not find enough overlap and that it could not find a consistent overlap. The first means too few matching points: the frames share too little, or the shared region is featureless like sky, water or a plain wall. The second means matches were found but do not agree on one transform, which almost always means parallax — you moved sideways between frames, or something close to the camera sits in the overlap. In both cases the fix is in the shooting, not the settings: retake from a fixed spot with more overlap and some texture in the shared region.

What the result looks like

A stitched panorama has irregular edges, because each frame was rotated slightly to match its neighbour and the composite is the union of all of them. That is normal and is why every phone panorama app crops the result. The tool leaves the edges so you decide the crop; open the download in any editor and trim to the largest clean rectangle. Expect a slight softening across the blended seam, which is the feathering doing its job — a hard cut would be sharper but would show any exposure difference as a line. Resolution is preserved, so four 4000-pixel frames with a third of overlap produce an image roughly 11,000 pixels wide, which is plenty for a wide print.

Privacy and limits

Everything runs in your browser. The frames are decoded locally, matched and blended by JavaScript in a background thread on your own device, and the result is offered as a download; nothing is uploaded. The stitcher takes two to four frames of JPG, PNG or WebP at up to 5 MB each, and very large sets should be resized first because matching cost grows with resolution. It handles panning, in-plane rotation and modest scale change, and does not model perspective, so a very wide sweep with strong parallax will align worse than a desktop tool with a full projective model. There is no signup, no watermark and no limit on how many panoramas you make.

Frequently asked questions

How much should the photos overlap?

About a third of each frame. Under a fifth and the stitcher may not find enough matching points; over half is wasted.

Can I stitch more than four photos?

Not in one go. Stitch the first four, then stitch that result with the next frames.

Why does it say it could not align the images?

Too little overlap, a featureless shared region such as sky, or parallax from moving sideways between frames. Retake from one spot with more overlap.

Do the photos need to be in order?

Upload them in the order they were taken, left to right or top to bottom. It makes matching more reliable.

Why are the edges of the panorama uneven?

Each frame was rotated slightly to align, so the composite has ragged edges. Crop to a clean rectangle in any editor.

Is anything uploaded?

No. Matching and blending run in your browser and the files never leave your device.

Photo Stitcher Online — Merge Photos Into One Panorama