Developers

Give your agents a payment proposal API.

REST. OpenAPI-described. HMAC-signed. Idempotent. Designed so an agent can express intent without ever holding the keys to a wallet.

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Agent API

Four verbs. One spend surface.

The agent-facing API is intentionally small. Most workflows are some sequence of these four calls.

Create proposal

Submit a signed payment proposal with amount, currency, merchant, and purpose.

Get spend capacity

Query the current spendable headroom for this agent in any supported currency.

Get proposal status

Poll for the lifecycle state — created, approved, executed, failed.

Receive webhooks

Subscribe to signed lifecycle events instead of polling — same auth model in reverse.

MethodPathDescription

POST/v1/proposalsCreate a signed payment proposal on behalf of an agent.
GET/v1/spend-capacityGet current spend headroom — owner balance bounded by agent cap and policy.
GET/v1/proposals/{id}Fetch the current state of a single proposal.
GET/v1/proposalsList proposals scoped to the calling agent.

Security

Five headers. Replay-proof by construction.

Each request carries its own integrity proof. The platform recomputes everything before accepting.

X-API-Key

Identifies the calling agent and resolves the signing key.

agt_live_4f2c8a9c…

X-Timestamp

Unix seconds, current. Requests outside a 5-minute window are rejected.

1747920000

X-Nonce

Single-use random value. Replay protection — reusing a nonce within the window fails.

0a8f3c1e7b…

X-Signature

Hex HMAC-SHA256 over `<ts>.<nonce>.<method>.<path>.<sha256(body)>`.

a91c4f…b9e2

Idempotency-Key

Client-chosen UUID. Re-sending the same key returns the original result.

0193b7c0-…-d4f1

Signature contract

One canonical base string per request.

The signature input is fully deterministic — no field is optional, no whitespace is allowed. Mismatches fail closed.

signaturetext

// signature base string (newline-free, concatenated with '.')
<timestamp>.<nonce>.<method>.<path>.<sha256(body)>

// signature
hex(HMAC-SHA256(base_string, agent_signing_key))

Example

A complete proposal request.

Headers on one side, payload on the other. Drop these into your client; the rest is auth handling.

requesthttp

POST /v1/proposals
Host: api.0x1e.ai
X-API-Key:         agt_live_4f2c8a9c…
X-Timestamp:       1747920000
X-Nonce:           0a8f3c1e7b…
X-Signature:       a91c4f…b9e2
Idempotency-Key:   0193b7c0-…-d4f1
Content-Type:      application/json

body.jsonjson

{
  "amount": "249.00",
  "currency": "USD",
  "merchant_name": "API Provider",
  "category": "compute",
  "description": "Top up inference credits"
}

Re-sending the same Idempotency-Key returns the original proposal — never creates a duplicate. Important for retry loops on flaky networks.

Webhooks

Subscribe instead of polling.

Five signed events cover the full proposal-to-settlement lifecycle. Same HMAC contract, applied in reverse.

proposal.approved
Owner confirmed the proposal. Funds have been reserved atomically.
proposal.denied
Owner rejected the proposal. No reservation took place.
payment.succeeded
Payment rail confirmed the transaction. Reserve has been committed.
payment.failed
Payment rail rejected the transaction. Reserve has been released.
refund.succeeded
Refund completed against an original transaction. Owner balance restored.

SDKs · coming soon

Official client libraries are on the roadmap.

TypeScript and Python first. Until then, the REST contract plus a few lines of HMAC code in your language of choice gets you a production client — early-access partners get reference implementations.

TypeScript
Python
Go (community)
Ruby (community)

Request reference impl

Ship the agent integration this quarter.

Early access partners get keys, OpenAPI spec, reference HMAC client, and direct support.

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