A signed fact attestation is a cryptographically signed statement that a real-world fact an AI agent depends on — a merchant, price, counterparty, or claim — is true, independently verifiable against the issuer's public key. It lets an autonomous agent trust a fact without trusting the source: the math proves it, not a reputation.
Most "trust" tools for agents emit judgments — a risk score, a reputation number, an opinion — which are subjective and conflicted. 0n1x signs facts: verifiable observations of reality (this domain was registered in 1995; this price is X; this merchant resolves to a real entity) sealed with an Ed25519 signature. A judgment asks you to trust the grader; a signed fact asks you to trust nothing but the evidence and the key.
0n1x is a neutral trust layer that issues signed fact attestations over x402 (USDC on Base mainnet) and anchors them to the ERC-8004 Validation Registry. Every attestation is independently verifiable against 0n1x's published key, and accumulates in a live public ledger — /ledger, with the canonical signed state at /pot. 0n1x earns nothing from what it grades — neutral by design.
More: 0n1x — Proof of Agent Execution · Verify before pay · Repo