Trim Image Whitespace (Auto Crop)

Screenshots, scans, product photos and exported charts often come with empty white, black or transparent space around the part you want. This tool finds that border and crops it away automatically, so you do not have to drag a crop box on every file. Set how strict the match is, keep a few pixels of breathing room if you like, and trim a whole folder of images at once — in your browser, without uploading anything.

How to use this tool

1. Choose one or more images.
2. Leave "Detect from the corners" on, or pick transparent areas or a specific colour.
3. Raise the tolerance for JPG photos, scans or soft shadows; add a margin to keep some space.
4. Download the trimmed images, or all of them as a ZIP.

Formula

a pixel is border if |R − R₀|, |G − G₀| and |B − B₀| are all ≤ tolerance × 255 (or its alpha is ≤ tolerance × 255); the crop box is the smallest rectangle containing every non-border pixel, grown by the margin

Automatic detection treats the image as transparent when at least two corners are transparent; otherwise the border colour is the colour shared by most corners. Rows are scanned from the top and bottom, then columns from the left and right, until a row or column contains content. The kept pixels are copied exactly, with no resampling.

Example

A 1200 × 800 screenshot with 150 px of white on the left and right and 100 px above and below its content is cropped to 900 × 600 px, starting at (150, 100). With a 10 px margin it becomes 920 × 620 px starting at (140, 90), and 42.5% of the area is removed without it.