Get startedWhat is Exchain
What is Exchain
Independent authorization for agent payments: what Exchain does, what it guarantees, and where it runs today.
Exchain is independent authorization for agent payments.
AI agents now pay for services, settle trades and move treasury funds on their own, and on-chain payments are final. Exchain is the independent authorization seat beside the agent's wallet: every payment needs Exchain's co-signature, and Exchain signs only when the payment fits the mandate the owner set. Exchain is chain-agnostic by design: it adds its signature to a standard wallet the owner keeps and applies the same mandate whichever chain settles the payment. It cannot move funds alone, the owner can leave with their own key at any time, and every decision is published in a signed journal anchored daily on Cardano mainnet.
The problem
- Agents act at machine speed, without a person reviewing each payment.
- On-chain payments are final. There is nothing to reverse.
- Limits kept inside the agent's own process run next to its key, so they stop nothing once the agent or its key is compromised.
On final money, the only control is the one before the payment.
Maker-checker for machines
The agent makes each payment, and Exchain checks it against the mandate before it co-signs. A refusal signs nothing, so the payment never exists on chain.
What card authorization does for card payments, Exchain does for agent payments: a yes or no on every payment, enforced by a signature the wallet requires.
Guarantees
| Guarantee | How | Details |
|---|---|---|
| The agent cannot spend outside the mandate | Every agent spend needs Exchain's signatures, and Exchain checks the mandate first | Mandates |
| Exchain cannot move funds alone | Exchain holds no agent key, and its decision service holds no key that signs payments | Trust model |
| The owner can always exit | The owner key alone withdraws the funds or rotates the agent, with no Exchain signature | Owner controls |
| Every decision is public | Published, signed hourly per wallet, anchored daily on Cardano mainnet | Journal |
What Exchain is not
- Not a wallet. The owner keeps a standard wallet: a Masumi smart wallet or a stock Safe.
- Not a custodian. Exchain holds no key that moves funds alone.
- Not a chain or a token.
- Not an x402 facilitator. Any x402 facilitator settles the payment.
Use cases
| Use case | What the agent does | What the mandate enforces |
|---|---|---|
| APIs and data per call | Pays a data or tool API for each request | A cap per payment, a limit on payments per minute and, on x402, the seller's signed price |
| Compute and inference | Buys model inference or GPU time in small increments as a task runs | A rolling daily total and a lifetime budget for the wallet |
| Agent-to-agent services | Hires another agent for a task and pays it through escrow | Registered sellers only, at no more than their published price, with a cap per seller |
| Procurement | Places routine orders with approved suppliers | Only sellers on the allow list, a cap per seller and a daily total |
| Several agents, one budget | Runs a team of agents that pay from one wallet | A cap per agent within the wallet's daily total |
Platforms and node operators that let agents pay can start with Masumi nodes. Sellers and auditors who check a payment start with Verify a decision.
Terms
| Term | Meaning |
|---|---|
| Mandate | The limits Exchain checks before it co-signs |
| Co-signature | Exchain's signatures on a payment, given only when the payment fits the mandate |
| Attested quorum | The independent signers that co-sign for Exchain. Each runs in a hardware-isolated, attested enclave and is verified against the approved image before use. Every member must sign |
| Guarded wallet | A wallet that needs both the agent key and the attested quorum's signatures for every agent payment |
| Journal | The public, signed record of every decision |
Next: Quickstart.