Proof a real human did the work.
Bitcoin’s proof of work shows a machine spent compute. Ours shows the opposite: an ID-verified, live person did a specific task.
- One seal per task
- Free to verify
- Checked offline
AI-generated imageTwo kinds of proof of work.
Classic proof of work
Proves a machine burned energy on computation. Silent on whether a person was involved.
5arz proof of work
Proves a verified, live person did a label, rating, demo or real-world action. A credential, not consensus.
Why it’s scarce now
51% of web traffic is bots (Imperva Bad Bot Report, 2025). “A person did this” is now hard to prove.
Verify, work, sign, check.
Verify the human
ID + liveness with our partners. 5arz never receives the selfie or ID image.
Do the work
Cognitive (label, rank, moderate) or kinetic (a real-world action).
Sign it
A Proof-of-Human-Fulfillment credential bound to the task, the account and the moment.
Check it
Anyone validates it offline against our public JWKS. No SDK.
Verified human work, in practice.
AI training data and RLHF
Show a real person produced each label, ranking or evaluation.
Data and evals →Agent-commissioned work
When an agent pays for human work, the credential proves a person did it.
For AI agents →Marketplaces and freelance
Attach proof to delivered work so buyers can check it themselves.
Human tasks →Field and kinetic work
A verified person signs for a delivery, an inspection or an on-site task.
Proof of labor →Checking a seal is free.
On every plan, at any volume. Plans add seal volume, the dashboard and support.
Proof of work, answered
What is proof of work for humans?
Evidence that a real, ID-verified, live person did a specific task — a label, rating, demo or real-world action. 5arz issues it as a signed credential anyone can verify.
How is this different from Bitcoin proof of work?
Bitcoin’s proves a machine spent energy on computation. Ours proves a person — not a machine or a model — did the task. It’s a credential, not a consensus mechanism.
Why does it matter for AI training data?
A signed record that a real person produced each unit lets AI teams trust the human data they pay for.
How do I verify a credential?
Each credential is an ES256 JWT. Validate it against our public keys at api.5arz.com/.well-known/jwks.json with any JWT library.
How much does it cost?
Checking a seal is free at any volume. Free plan: 1,000 seals a month, no card. Starter $99, Growth $499, Scale $2,499 a month. People never pay to be verified.
Prove the human behind the work.
1,000 seals a month free. No card, no sales call.