# When to rewrite text, and when to strip a file

Originally published at https://gifi.ai/guides/rewrite-vs-strip.

Use a rewrite when the mark is statistical — a ChatGPT, Claude or Gemini trail lives in the words the model chose. Use a strip when the mark is in the file: C2PA credentials, EXIF, XMP, document properties, or invisible Unicode. Gifi will not pretend one credit does both jobs, because they have different costs and different standards of proof.

Reviewed by [Can Balkaya](https://gifi.ai/authors/can-balkaya). Published 2026-08-17; updated 2026-08-17.

## How to verify the job

1. **Identify the surface.** Use inspection to distinguish deletable Unicode or file metadata from a statistical pattern in ordinary words.
2. **Choose one action.** Clean named bytes from a string or file, or rewrite prose when the signal lives in word choice.
3. **Verify only what is verifiable.** Confirm removed characters and metadata independently; do not treat a rewrite as a detector certificate.

## If the mark is in the words

SynthID-Text does not add characters. It biases which token the model picks at each fork. Light edits usually keep that trail. A rewrite chooses different words, which breaks the keyed sequence.

We cannot see any vendor’s key, so we cannot certify their detector. A rewrite changes the prose. That is all an honest tool can say.

## If the mark is in the file

C2PA, EXIF, XMP and Office/PDF properties are bytes with names. They can be listed, then deleted. Invisible Unicode — zero-width spaces, tag characters, a byte-order mark — is the same idea inside a string. The home-page paste shows those characters before you spend anything.

Stripping a file does not disturb a statistical text watermark in a caption. Rewriting a caption does not remove GPS from the photograph beside it.

## What a credit buys

One credit is one rewrite candidate, or one file cleaned. Pasting on the home page is free. Continuing a rewrite, or sending a file to be stripped, is the paid work that runs on our machines.

## Questions

### Can I strip a text watermark like EXIF?

No. There is nothing to delete. The mark is the path through the vocabulary, not a hidden character.

### Can I rewrite a JPEG to remove C2PA?

No. Rewriting is for prose. A photo needs the file cleaner.

### Which should I do first?

Inspect first. The home page will show invisible characters in text, and what metadata a file is carrying, before you sign in.

## Primary sources

- [Google DeepMind on SynthID](https://deepmind.google/models/synthid/)
- [C2PA specification and resources](https://c2pa.org/)