Screenshot Stitcher: Join Overlapping Screenshots Into One Long Image

Stitch overlapping screenshots into one long image. Overlaps are found automatically and repeated headers and footers are removed. Free, and your files never leave your browser.

What it does

Screenshot Stitcher joins several overlapping screenshots, such as the frames of a scrolling capture, into one seamless image. Drop in the frames in any order and it works out where each one overlaps the next, trims any repeated header or footer, and builds a single tall (or wide) picture you can preview and download as PNG, JPEG or WebP.

It handles the usual problems of stitching by hand: status bars and sticky navigation that repeat in every frame, frames in the wrong order, frames of slightly different widths, and results too large for a browser to export in one piece.

How it works

Neighbouring frames are compared edge to edge. Each frame is shrunk to a small grayscale version, and the tool tests every possible overlap between the bottom of one frame and the top of the next. A good overlap is one where the two strips match almost line for line. The best candidate is then refined at full resolution, down to the exact pixel.

Every seam gets a confidence rating (High, Medium, Low or No overlap). Repetitive content, such as a table of identical rows, is flagged as Low rather than trusted blindly, and you can correct any seam by typing an overlap or nudging it a pixel at a time.

A header or footer that appears at the same place in every frame (a phone status bar, a sticky site menu, a bottom toolbar) is detected by comparing the edges of neighbouring frames, then cropped from every frame except the first (for the top) and the last (for the bottom). A small change inside it, like a clock, does not confuse the detection. You can also type the sizes by hand.

How to use it

1. Add your screenshots: click, drag and drop, or paste with Ctrl/⌘+V. Files dropped together are sorted by file name.
2. Check the preview. Coloured markers show each seam, and the list below shows its confidence.
3. If the order is wrong, drag frames, use the arrows, choose Sort by name, or press Suggest order to order them by how well they overlap.
4. Adjust anything that needs it: the overlap of a seam, the header and footer sizes, how frames of different widths are matched, the background, or a soft blend across the seams.
5. Press Preview & export to check the result and download it. Very tall results are split into numbered parts in a ZIP, or scaled down to fit, as you choose.

Features

• Vertical or horizontal stitching
• Automatic overlap detection with a confidence rating for every seam
• Automatic removal of repeated headers and footers, with manual override
• Suggest-order button that arranges scrambled frames by overlap
• Frames of different sizes: scale to the widest, narrowest or first frame, or keep sizes and align them
• Optional soft blend across seams, and a background colour (or transparent for PNG and WebP)
• Skip or remove frames, with undo, and drag to reorder
• Splits oversized results into parts, or scales them to fit the browser limit
• Your work is kept on your device through a refresh, and Clear all removes it
• Send the result to other Run Local Tools, for example to annotate it, blur sensitive parts, crop it or compress it

If the stitched image is going into a post or a document, the screenshot beautifier can frame it afterwards.

Privacy

Stitching is fully local. Your screenshots are decoded and combined by your own browser, and nothing is uploaded to a server. There are no network features in this tool.

Your frames are saved on your own device so a refresh does not lose your work. This follows the site's "keep files" setting. Use Clear all & saved files to delete them at any time.

Only one thing loads from outside: if you add an iPhone HEIC photo that your browser cannot open itself, a small converter library is needed. While the site's libraries are not yet self-hosted, first use of it downloads that library from a public CDN and then it works offline; once they are self-hosted it is served from this site and the tool can be saved for offline use. No image data is sent either way. (Publisher: keep the sentence that matches libs.js: vendored:false or vendored:true.)

Supported formats and limits

• Input: PNG, JPEG, WebP, GIF, BMP, AVIF and HEIC/HEIF (browser support for AVIF varies; HEIC is converted when your browser can't open it).
• Output: PNG, JPEG or WebP. JPEG cannot be transparent.
• Size: browsers cap a single canvas at about 16,384 pixels per side. Taller results are split into parts (a ZIP) or scaled down, whichever you choose.
• Frames should come from the same page or screen at the same zoom. Frames with very little visible content in the overlap, or no overlap at all, can't be matched automatically. They are joined edge to edge and marked, and you can enter the overlap yourself.
• Many large frames use a lot of memory. If the tab slows down, stitch in smaller batches.

FAQ

How much do my screenshots need to overlap? Enough to contain some visible content, such as a few lines of text or an image edge. A strip of plain white background can't be matched. Overlaps of roughly 10% of a frame or more work best, and larger is safer.

Why does a seam say "Low" or "No overlap"? Low means the match is repetitive or low-contrast, so more than one position fits, and you should check the preview. No overlap means no convincing match was found, so the frames are joined edge to edge. In both cases you can type the overlap in pixels for that seam, or press Re-detect to undo your change.

Will the header and footer of every frame appear in the result? No. A header that repeats in every frame is kept once, at the top of the first frame, and a repeated footer once, at the bottom of the last. Turn off automatic detection if your frames have no such bars, or to set the sizes yourself.

Can I stitch horizontally, like a panorama or a wide timeline? Yes. Switch Direction to Horizontal. Overlaps and left/right bars are detected the same way. It is meant for screen captures, not for photographs taken with a moving camera.

The result is very tall. Can I still export it? Yes. Browsers limit canvas size, so the tool either splits the picture into numbered parts in a ZIP or scales it down to fit. You choose which, and the page tells you what will happen before you export.

Is it free, and do I need an account? It is free and needs no account or sign-up.