The sealer · Folio II
runs in your browser · no upload
§ Drop, seal, share

Seal a screenshot

Drag a PNG or JPG below. Your browser hashes it locally and receives back a QR-stamped version + a public receipt URL. We only ever see the hash. The image itself never leaves your machine.

Drop a screenshot here
or click to pick · PNG, JPG, WebP · up to 25 MB
Your image is hashed in your browser. Only the SHA-256 hash (32 bytes) is sent. We never see the image.
We do not verify this URL. It's shown on the public receipt page as context only.
§ How sealing works
  1. Step 1. You drop an image. Your browser computes its SHA-256 hash locally. Only that 32-byte hash is sent to our Worker — the image stays in this tab.
  2. Step 2. Our Worker signs the hash with our ECDSA P-256 key, mints a short receipt ID, and submits the hash to the OpenTimestamps calendar for an external timestamp anchor.
  3. Step 3. Your browser draws a QR code linking to the receipt page, composites it onto the original image, and hashes the result. The second hash (stamped) is sent back to lock the receipt against QR-paste fraud.
  4. Step 4. You get the stamped image. Anyone who scans the QR lands at the public receipt page and can drop the image to confirm the bytes still match the sealed timestamp.