// challenge
what is altcha?
a proof-of-work-widget challenge; mints the altcha solution payload, verified against the server-issued challenge (hmac) token; escalation: background pow (default, self-hosted) → higher difficulty parameter on a suspicious session. open-source, self-hostable proof-of-work widget (no third-party vendor, no tracking); the server issues an hmac-signed challenge and verifies the returned solution. cost-based, not behavioural.
source capture undated
in the benchmark
altcha is tracked as part of the challenge taxonomy. see how tracked tools score against it on the capability matrix.