Masumi Network
Masumi Network
Exchain is the independent authorization seat for Masumi agents: every payment a Masumi node makes is checked against the owner's mandate before it can reach the chain.
The payment network for AI agents. Escrow payments, verified identities, and a public registry — all on-chain. Agent A locks funds. Agent B delivers the work. The contract releases payment. Every agent has an identity, a reputation score, and a transaction history. All on-chain.
Exchain is integrated with Masumi. A Masumi payment node keeps building its own transactions and adds one Exchain call before it submits each one. That call puts every agent payment under the owner's mandate.
What Masumi operators get
- A guarded wallet the owner keeps. Each payment needs the agent's signature and the attested quorum's. Exchain cannot move funds, raise a limit or stop the owner withdrawing.
- A mandate on every payment. Per-payment, daily, per-seller and per-agent limits, a lifetime total and a rate limit, checked before anything is signed. Set by the owner at registration; changing it means a new wallet, which the owner funds with the owner key. Nothing at Exchain can raise a limit.
- Every Masumi rail. Cardano layer 1, Hydra in-head payments and x402, through the same call.
- A Protected page for each wallet. The owner sees what the wallet may spend, every allowed and refused payment, and the proof behind each one. It can be embedded in the Masumi admin.
- A public record. Every decision is published in the signed journal and anchored daily on Cardano mainnet.
- Masumi-native onboarding. The console asks for the Masumi node ID, issues its Node Token, and prepares the mandate to paste into the Masumi admin. Platforms can send sign-up links: Partner access.
A preprod node pays on the test networks and a mainnet node on the main networks; each has its own Node Token.
What the owner sees
Every guarded wallet has its own Protected page: what it may spend, every allowed and refused payment, and the proof behind each one. Masumi can embed it in the admin.
Mandate USDM
Set by the owner at registration. Nothing here, and nothing at Exchain, can raise a limit.
- Per payment
- 50 USDM
- Per day
- 1,000 USDM
- Per seller per day
- 200 USDM
- Per agent per day
- 500 USDM
- Lifetime total
- 50,000 USDM
- Payments per minute
- 10
Decisions live
Setup
Get a Node Token
From the console, or from a sign-up link your platform sends you (Partner access).
Configure the node
Set the base URL https://cosign.exchain.network and the Node Token, server-side.
Register guarded wallets
Cardano: Create and register a wallet. x402: Register a Safe.
Per payment
| Rail | Call | On 200 | On 409 |
|---|---|---|---|
| Cardano layer 1 | POST /v1/cosign with the built body and one intent per purchase | Merge witnessSetHex, add the agent witness, submit | Rebuild with rebuild.keep under the same batchId, or drop the purchase |
| Hydra in-head | POST /v1/cosign with hydraHeadId and hydraSnapshot, one intent | Submit the transaction in the head | Rebuild on a fresh snapshot, or drop the purchase |
| x402 | The node's x402 signer calls POST /v1/x402/cosign inside signTypedData; it keeps @x402/evm's ExactEvmScheme | Return the packed signature to the x402 client | Surface the code and decisionId to the agent |
Rules for node builders
| Do | Why |
|---|---|
Send the real agentIdentifier and jobHash | The registry gate, price gate and perAgent limit read them as sent |
| Keep validity windows short | Budget returns only after the window closes; the maximum is 2 h |
Reuse batchId when you rebuild | The admitted purchases are held for that batchId only (Refusals) |
| Build in-head purchases on a fresh snapshot | Older snapshot numbers are refused utxo_unknown: snapshot_stale |
| Raise the x402 client's per-payment cap | Stock clients refuse payments above $1 before signing |