Proof of human, explained.
What proof of human means, how it differs from KYC and CAPTCHA, and how anyone can check one — free.
- 5 min read
- Free to verify
- Works offline
- proof of humannounDefinition
- A signed credential showing that a real, verified person did a specific action — which anyone can check without asking the issuer.
- Also called a human-verified seal. Related: proof of personhood, Know Your Agent.
A person verifies once. Each action they take can carry a seal saying who, what and when.
The seal is signed, so anyone can check it offline. Nobody has to share an ID.
Source: Imperva Bad Bot Report, 2025
Most traffic isn’t a person anymore.
When bots and AI agents act at scale, “a person did this” becomes worth proving.
- AI agents act for people — services need to know who stands behind them.
- Labels, reviews and approvals are worth more when a person made them.
- A passed checkbox stays on one site. A signed seal travels with the action.
Four checks, four different questions.
None is “better”. Pick the one that answers your question.
| Compared on | Proof of humanWhat 5arz issues | Proof of personhood | KYC | CAPTCHA |
|---|---|---|---|---|
| The question | Did a verified person do this action? | Is this human unique? | Exactly who is this person? | Is this session likely a person? |
| How it’s done | ID + liveness once, then a signed seal per action | Biometrics or a social graph, one ID per person | ID documents and checks run by the business | A puzzle or a risk score in the browser |
| Others can check it | Yes — offline, free | Usually, via its protocol | No — it stays with that business | No — a pass for one site |
| Shares identity | No — a pseudonymous seal | Usually not | Yes — that is the point | No |
| Best for | Approvals, labeled data, agent requests | One per person: votes, airdrops | Regulated onboarding: banks, exchanges | Blocking bulk bots on forms |
Verify once. Seal it. Anyone checks.
Three steps. Press Play, or tap a step.
With a partner, on your own phone
Run by Stripe Identity or Didit. 5arz gets a signed result — never your selfie or ID image.
verify_human(sessionId)
ES256 · 5arz-oracle-2 · counts as one sealThree formats, in plain words.
All signed ES256 with one public key. check_credential verifies any of them — no API key.
Proof-of-Human-Fulfillment. One seal for one action: who, what and when.
Proof of personhood for an account or an AI agent. Used for Know Your Agent.
The IETF SD-JWT VC format, for wallets and standards-based verifiers.
What a seal doesn’t prove.
- Not one account per person. Read sybil_checked before gating votes, airdrops or bonuses.
- Not that the content is true. It proves who acted and when — not what they said.
- Only as strong as the ID check. That check is run by our verification partners.
{
…
"sybil_checked": false
}
False means: verified person, uniqueness not checked.
Anywhere “a person did it” matters.
Is proof of human the same as KYC?
No. KYC tells one business exactly who you are. Proof of human shows a verified person did something, without handing over who they are.
Does 5arz see my ID or selfie?
No. Our partners, Stripe Identity and Didit, run the check. 5arz receives only a signed result, and we don’t sell personal data.
How do I check a seal?
Verify its ES256 signature against our public key — in your browser, with any JWT library, or with check_credential. It’s free.
Does one seal mean one account per person?
Not by itself. Read sybil_checked in the claims before gating anything that should be one per person.
What does it cost?
Checking a seal is always free. Issuing seals starts free with 1,000 a month. People never pay to be verified.
Can an AI agent carry proof of human?
Yes. An agent can carry a pop_jwt showing a verified person stands behind it. That’s Know Your Agent.
Make your next action provable.
Start free with 1,000 seals a month. Checking a seal is always free.