Proofhand · explainer
Proofhand replaces image puzzles on sign-up, login and contact forms with an invisible proof-of-work check and one server-side verification.
Proofhand is a CAPTCHA replacement: the visitor's browser solves a small proof-of-work challenge silently, the form carries a token, and the server verifies it once with a call shaped like reCAPTCHA's siteverify.
It is built and run by Jacaranda Labs in Harare, Zimbabwe. Live: https://attestos.whop.site
Proofhand replaces image puzzles on sign-up, login and contact forms with an invisible proof-of-work check: the browser solves it silently, the form carries a token, and the server verifies that token once.
Product, growth and platform teams, publishers and documentation sites.
Markets: Global.
Invisible challenge. A small proof-of-work check runs in the visitor's browser while the page loads.
Token on the form. The form carries a token the visitor never sees.
One verification. The server verifies the token once, with a request shaped like reCAPTCHA's siteverify.
Crawler policy. AI crawlers can be made to pay for access or stay out, deliberately.
Drops in. It replaces puzzles on sign-up, login and contact forms without a redesign.
Tiers. From a free tier to IntegrityRuntime, AgentPass, Hardware Gateway and Enterprise.
Every price above is the live checkout price; the links go straight to the plan.
Proofhand replaces image puzzles on sign-up, login and contact forms with an invisible proof-of-work check: the browser solves it silently, the form carries a token, and the server verifies that token once.
Yes. It does the same job as reCAPTCHA or hCaptcha without asking a real visitor to identify traffic lights, and the server-side verification call is shaped like reCAPTCHA's siteverify.
There is a free tier. IntegrityRuntime Pro is $49 a month, AgentPass Pro is $99 a month, Hardware Gateway Pro is $149 a month and Enterprise is $299 a month.
Bots that solve puzzles with paid services get through those puzzles anyway; a proof-of-work check costs a machine real computation while costing a person nothing.
Yes. The change is a token on the form and one verification call on the server, so the form itself does not need redesigning.
Yes. Proofhand lets a site make crawlers either pay for access or stay out, instead of blocking all automation or allowing all of it.
It asks nothing of the visitor beyond submitting the form, so there is no visual or motor task to fail.
Figures and prices are generated from Proofhand's live billing table and published at https://attestos.jacaranda-labs-v2.workers.dev/facts.json, which is the authoritative copy.
_Jacaranda Labs, Harare, Zimbabwe._