SDK & API Support

Where to start as an integrator, and where to go when something breaks. The deep technical references live in the developer sections of these docs — this page is the map.

The packages

• @furlpay/furlpay-node — the server SDK for the REST API.
• @furlpay/gateway — self-hostable x402 paywall for your own endpoints.
• @furlpay/mcp-server — expose FurlPay to Claude and other MCP clients.
• @furlpay/cli — terminal workflows, webhook forwarding, and an MCP server.

npm install @furlpay/furlpay-node
# or paywall your own API:
npm install @furlpay/gateway

Start here

• Quickstart — first API call, webhook forwarding, checkout widget.
• API Routes — the REST surface, auth, idempotency.
• Webhook Events — signature verification for every inbound event.
• Error Codes and Rate Limits — what a 4xx is telling you.

The three most common integration issues

• Webhook signature failures — verify the HMAC over the raw request body, before any JSON parsing or re-serialization touches it. Framework middleware that pre-parses JSON is the usual culprit.
• 429s in loops — respect the Retry-After header instead of hammering. Budgets exist per route; the rate-limits page lists them.
• Duplicate payments on retry — send an Idempotency-Key header on money-moving POSTs. Retries with the same key replay the original response instead of paying twice.

Getting help

Open a ticket in the developers category from the Support Center with the request id from the error response, your endpoint, and a timestamp. Never include API keys — pasted secrets are stripped automatically, so a ticket can't leak them, but a rotated key is still safer than a stripped one.