SignUnder and Resemble AI's Watermarker, compared

What Resemble offers

From its pricing page, read 12 October 2026: Flex at $0 a month with "no subscription fee" and pay-as-you-go credits; Team at $350 a month ($280 billed annually); Business at $1,000 a month; Enterprise on request. Watermarker encodes cost $0.0005 a call and decodes $0.0002 on every tier; image detection is $0.035 an image on Flex and $0.015 on Team and Business. The page describes the Watermarker as "Provenance and C2PA compliance" and the Flex tier as including "Check for SynthID and sign C2PA records". Its changelog of 15 June 2026 says "The Watermarker can now sign outputs with C2PA content credentials" and "It can also detect Google SynthID watermarks".

The pricing page does not mention Article 50 or the EU AI Act; the Watermarker's own page did, by name, when we read it on 8 October 2026. The changelog says nothing about which certificate signs the manifests or whether they validate against the Trust List.

Where the difference is

Conformance. We checked the Conforming Products List on 12 October 2026: 248 records, 146 applicants, no Resemble. Under the Certificate Policy a Trust List CA issues claim signing certificates only to listed products, so whatever Resemble signs with today, a verifier that checks the Trust List reports it as Unrecognized (why that happens). This is fixable on Resemble's side, for free, in a median of 17 days; we watch the list weekly and will update this page the day it changes.

Whose name. Even once listed, Resemble's certificate would name Resemble. Your name on the signature needs your own listing, which no hosted signer does for you (the own-name guide). SignUnder's product is that listing, your certificate, your key in a KMS, and signing under them.

Detection. Resemble's detection is an authenticated API answering "is this ours or SynthID". The Code of Practice's duty is a detection solution for your own system's outputs, public, with an interoperable mechanism by 2 February 2027; SignUnder runs that per customer, under the customer's subdomain.

Rules. Resemble does not maintain jurisdiction or platform rule packs. SignUnder evaluates each output against versioned packs and records which version applied.

Where Resemble is stronger

A proprietary, multimodal watermark with years of production use, an audio heritage that SignUnder does not have, a text watermark, and prices for the primitive that are the market's reference. If what you need is a watermark and a SynthID check, with a signature in the vendor's name that you accept will display as Unrecognized until Resemble is listed, it is a reasonable choice.

Read from Resemble's own pages on the dates shown. Tell us if this is out of date and we will correct it with the date of the correction.

Changes

• 2026-10-12 — First published.

Not legal advice. Every cell comes from the vendor's own pages on the date shown.