Sign your AI outputs with verifiable citation attestations.
Hosted CiteSig SIGS: one API call per response, an Ed25519 signature over the claim + sources, verifiable by anyone with the CiteSig Chrome extension or open-source verifier.
Sign up with email, Google, or GitHub. No card required for the free tier.
How it works
STEP 1
Sign up
Email, Google, or GitHub. Free tier gives 50 signatures/month, no card required.
STEP 2
Get your API key
One live key issued on signup. Displayed once — save it somewhere safe.
STEP 3
Call the signing API
POST /api/v1/sigs/sign with your claim + sources. Returns an attestation any verifier can check.
Pricing
Free
$0/mo
50 signatures/mo
1 sig/sec
Shared free-tier signer DID (watermarked).
POPULAR
Starter
$29/mo
1,000 signatures/mo
5 sigs/sec
Your own signer DID.
Growth
$99/mo
10,000 signatures/mo
20 sigs/sec
Your own signer DID.
Scale
$499/mo
100,000 signatures/mo
100 sigs/sec
Your own signer DID.
Upgrade from your dashboard after signing up. Stripe handles billing.
Verifiable by anyone
Signatures are open. Anyone can verify them with the CiteSig Chrome extension, the @citesig/core npm package, or the citesig PyPI package. Public keys are discoverable at /api/v1/sigs/keys.