auth.api.polymer.zone provides an asynchronous proof-generation and query service from Polymer Labs. Clients submit proof_request payloads to receive a job ID, then poll with proof_query to retrieve status and results; the service also supports payment proofs. It’s a straightforward API for adding verifiable attestations and payment verification into identity and authentication flows (docs: https://docs.polymerlabs.org/docs/build/prove-api-V2/api-endpoints).