How do you check a WebP for hidden metadata and C2PA?
A WebP file is a RIFF container made of named chunks. Exif, XMP, and C2PA Content Credentials can travel alongside its encoded image or animation data without appearing in the visible pixels.
Upload the WebP to the image checker. It parses the RIFF structure locally, reports supported EXIF, XMP, and C2PA chunks, validates embedded Content Credentials when possible, and can create a cleaned WebP without re-encoding its image or animation chunks.
Where WebP hides metadata
WebP uses a RIFF header followed by chunks identified with four-character codes. Visible image content usually lives in VP8 , VP8L, ALPH, or animated ANMF chunks. Metadata may live in separate EXIF and XMP chunks. The C2PA specification places a Content Credentials manifest store in a C2PA chunk at the end of the WebP container.
| Chunk | Purpose | Default action |
|---|---|---|
| EXIF | Camera, software, location, date, and other Exif fields. | Shown; removed by Privacy clean. |
| XMP | Extensible metadata used by editors, asset systems, and provenance workflows. | Shown; removed by Privacy clean. |
| C2PA | An embedded Content Credentials manifest store. | Validated when possible; removable by either cleaning policy. |
| ICCP | A color profile that affects rendering. | Always retained. |
| VP8 / VP8L / ANMF | Encoded image or animation data. | Always retained byte-for-byte. |
| Unknown | Future or application-specific data. | Reported as a warning and retained. |
How WebP metadata removal stays safe
Deleting a chunk alone is not enough. The cleaner recalculates the RIFF file length and updates the WebP VP8X feature flags so they accurately reflect whether Exif or XMP remains. It then parses the output again and compares a SHA-256 fingerprint of the retained render-relevant structure with the input. If that identity changes, the cleanup fails instead of offering a download.
Does removing C2PA remove every AI watermark?
No. It removes only the recognized embedded C2PA copy. A WebP may also contain a watermark encoded in pixels, and a durable Content Credential may be discoverable outside the file. The checker does not alter pixels or claim that metadata absence proves human authorship.
What does C2PA validation report?
The checker distinguishes an embedded structure from a valid signature and a trusted signer. “Trusted” means the credential validates and its signer chains to the configured official C2PA trust list. “Absent” means no embedded manifest was found; it does not rule out external provenance.
Can I audit the cleanup?
Yes. Download the local evidence report before or after cleaning. It records the input and output SHA-256 hashes, detected chunks, C2PA result, ruleset version, removal policy, and the render-relevant fingerprint comparison. It excludes the image pixels and filename.