Overview
The Laso Finance API uses the x402 protocol to gate endpoints behind crypto payments on Base (USDC). Agents and clients can programmatically order prepaid Visa cards (US only) or send Venmo/PayPal payments.How x402 works
Call a paywalled endpoint
Make a request without a payment header. You’ll receive a
402 Payment Required response containing payment details (price, recipient address, network).Construct a payment header
Use the details from the 402 response to create an x402 payment header with a Base USDC transaction.
Authentication
Paywalled endpoints extract the payer’s wallet address from the x402 payment header to identify the user. No separate API key is needed. The/auth endpoint returns auth credentials (idToken, refreshToken) that can be used as Bearer tokens to call other Laso Finance APIs at the callableBaseUrl returned in the response.
When the idToken expires, use the free /refresh endpoint to get a new one.
Endpoints
| Endpoint | Method | Payment | Description |
|---|---|---|---|
/auth | GET | $0.001 USDC | Get API auth credentials |
/get-card | GET | 1000 USDC | Order a prepaid Visa card (US only, for caller’s own use) |
/paid-data | GET | 1000 USDC | Deprecated — alias for /get-card |
/send-payment | GET | 1000 USDC | Send a Venmo or PayPal payment |
/refresh | POST | Free | Refresh an expired ID token |
Discovery
Agents can discover this API via:- OpenAPI spec: laso.finance/openapi.json
- AI plugin manifest: laso.finance/.well-known/ai-plugin.json
- LLM context: laso.finance/llms.txt