Start at the source.
Choose the original photo or short video you want to keep as a reference. Grainmark creates a seal of its visual content.
A reference for what you made
Keep the original
in the picture.
Your media travels. Give it a point of reference. Create a visual seal, then check how a later copy compares.
Private until you choose to publish
A moment worth keeping
Photos & short videos Private by default A seal you can take with you
Every original starts somewhere.
Bring your media. We’ll help you keep a reference.
Start with the original.
Upload a photo or short video to create its visual reference. Save the seal to check copies later.
Drop your original here
JPG, PNG, WebP, MP4, MOV & more · Up to 200 MB · Videos up to 20 seconds
Choose a fileYour file is uploaded for processing. New seals stay private; publishing is your choice.
Working on your media…
Download your seal and keep it with the original. You’ll use this JSON file to check a copy later.
View technical details
See how a copy compares.
Choose the original’s seal, then add the photo or video you want to check.
or use a seal you’ve saved
Drop your seal here
Grainmark JSON sidecar
Choose a seal2. Add the copy to check
Drop your copy here
Photo or short video · Up to 200 MB
Choose a fileChecks visual content against the seal. Audio and playback timing aren’t compared.
Working on your media…
Two files. One closer look.
Have both versions handy? Compare a copy directly with your original. No saved seal needed.
1. Your original
Drop the original here
The file you’re using as your reference
Choose a file2. The copy to check
Drop the copy here
The version you’d like to compare
Choose a filePhotos or videos up to 20 seconds and 200 MB each. This is a visual comparison.
Working on your media…
A visual reference, with clear limits. Understand your results
A small habit. A useful reference.
Make it. Mark it. Keep it.
Keep the connection.
Download the seal and store it alongside your media. It’s a small JSON file you can bring back when you need it.
Give copies some context.
Upload a later copy with your seal. See whether the checked visual content matches, partially matches, or differs.
A clearer picture.
With clear boundaries.
A little context makes a result more useful. Here’s what Grainmark can tell you.
What does a match actually mean?
It means the visual content checked by Grainmark matches the reference you supplied under its comparison rules. It doesn’t prove who captured the media, when it was captured, or whether the scene is real. Audio and playback timing aren’t checked. A seal is an unsigned comparison template. Small or subtle edits can be missed: check text, prices, small logos, and fine details manually.
What is a partial match?
Some checks use a limited set of reference images, or probes, instead of every frame. A partial match only supports those checked probes. It should not be read as a match for an entire video.
What stays private, and what gets shared?
New seals are private until you explicitly publish them. Save your downloaded seal or access token to use that private reference later. Seals contain embedded probe images: sharing the JSON shares those images, and publishing makes the sidecar public. Your uploaded media is processed on the server. Read the privacy policy.
Which files can I use?
Start with JPG, PNG, WebP, or a short video such as MP4 or MOV. Uploads can be up to 200 MB, videos up to 20 seconds and 600 frames, and media up to 1920 pixels on either side with at most 1920 × 1080 total pixels. Format support depends on the server’s media decoder.