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Fahad Farid
Fahad Farid

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How I strip photo metadata without a server

#javascript #privacy #webdev #tutorial

Your phone embeds a small diary in every photo: GPS coordinates, camera model, timestamps. Most “metadata remover” sites ask you to upload that diary to their server first — which rather defeats the purpose.

I build ToolVero, a set of 70+ free tools that run entirely in your browser, and the image metadata remover takes the opposite approach: the photo never leaves the device. Here’s the whole trick.

The method: decode, then re-encode from pixels

EXIF, GPS and XMP all live in the JPEG’s metadata segments — they are not part of the image data itself. So instead of surgically deleting segments, we throw the container away:

  1. Decode the uploaded JPEG into a canvas bitmap (pixels only — the browser’s image decoder does not carry EXIF into the bitmap).
  2. Create a fresh PNG from those pixels with canvas.toBlob('image/png').
  3. Offer that PNG as the download, under a neutral filename.

A PNG produced this way contains only IHDR, IDAT and IEND chunks. There is simply nowhere for EXIF to hide, because we never copied the original file’s segments — we re-created the image from raw pixels.

const img = await createImageBitmap(file);   // pixels only, no EXIF
const canvas = document.createElement('canvas');
canvas.width = img.width;
canvas.height = img.height;
canvas.getContext('2d').drawImage(img, 0, 0);
const clean = await new Promise(r => canvas.toBlob(r, 'image/png'));
// `clean` is a fresh PNG: IHDR + IDAT + IEND, zero metadata segments
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Why the output is clean by construction

PNG has no EXIF segment to preserve, and this method never copies the original file’s metadata segments at all — only the pixels. So EXIF, GPS and XMP have nowhere to survive. (Re-encoding to JPEG via canvas is equally clean, since canvas never writes EXIF — but PNG is the safer default because the format itself can’t carry the metadata.)

Why client-side matters

The privacy win isn’t just the stripped file — it’s that the stripping happens on your machine. No upload means no transit interception, no server logs, no “we delete after 24 hours” promises to trust. For a privacy tool, the architecture is the feature.

Try it on your own photos: Image Metadata Remover — everything runs locally in the tab.

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