Browse the catalog
See which x402 services are listed across the discovery sources 402Signal queries. Catalog listings are candidates, not live verification.
Browse catalogFind a paid API that works right now.
402Signal checks x402 services immediately before an agent uses them. It keeps catalog claims separate from what the endpoint actually returns, then gives the agent a route or a clear miss.
Base · Solana · Algorand
402Signal recommends the route. Your agent keeps the wallet.
DISCOVERY
What discovery sources say is available
Catalogs / Directories / Seller metadata
402SIGNAL
Check it now
Valid x402? / Payment terms? / Invocation info? / Fresh observation?
YOUR AGENT
Decide whether to spend
Own wallet / Sign / Pay seller / Call API
If the check does not pass, 402Signal returns a miss instead of quietly substituting an unverified service.
The live routing check costs $0.01 USDC. 402Signal does not hold your keys or pay the selected seller for you.
Use 402Signal in an agent
Call 402Signal through HTTP or MCP when your agent needs a fresh check before spending.
Developer docsPQ transparency · TestNet
Trust the history, too.
As agents start spending money on your behalf, there should be a record of what they relied on. 402Signal keeps a tamper-evident history of its routing evidence and periodically anchors that history to Algorand TestNet using Falcon-1024 authorization.
Latest checkpoint · Tree 13 · Block 66864432 · Confirmed
So if an agent pays for an API, research, or service, the evidence behind that routing decision can’t simply be rewritten later.