@kyvernlabs/pulse

x402 analytics middleware — capture every payment on Base, Stellar, and Solana with one line of code. Blockchain-verified, chain-agnostic, fire-and-forget.

Install

npm install @kyvernlabs/pulse

Usage

import { withPulse } from '@kyvernlabs/pulse'
import { withX402 } from '@x402/next'

const x402Handler = withX402(handler, {
  accepts: { scheme: 'exact', price: '$0.01', network: 'eip155:8453', payTo: '0x...' }
}, server)

// Every payment → your Pulse dashboard at kyvernlabs.com
export const GET = withPulse(x402Handler, {
  apiKey: 'kv_live_your_key_here'
})

Multi-chain by default

Pulse auto-detects the network from your x402 payment headers. No per-chain configuration needed — set up your x402 endpoint on any supported network and Pulse captures the payment with the right block explorer link.

| Network | Chain ID (CAIP-2) | Explorer | Asset | |---|---|---|---| | Base | eip155:8453 | basescan.org | USDC | | Stellar Mainnet | stellar:pubnet | stellar.expert | USDC / XLM | | Stellar Testnet | stellar:testnet | stellar.expert/testnet | USDC / XLM | | Solana Mainnet | solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp | solscan.io | USDC / SOL | | Solana Devnet | solana:EtWTRABZaYq6iMfeYKouRu166VU2xqa1 | solscan.io?cluster=devnet | USDC / SOL |

Adding a new chain is as simple as configuring your x402 endpoint to use it — Pulse will pick it up automatically.

Get Your API Key

1. Go to kyvernlabs.com/pulse/dashboard
2. Sign in with email, Google, or wallet (Privy)
3. Your kv_live_ key is generated automatically — find it on the API Keys page

What Gets Captured

| Field | Source | |-------|--------| | Endpoint path | Request URL | | Payment amount (USD) | payment-signature header | | Payer wallet address | payment-response header | | Blockchain tx hash | payment-response header | | Network (CAIP-2) | payment-signature / payment-response header | | Asset (USDC, XLM, SOL, etc.) | payment-signature header | | Response latency | Measured by middleware | | Status (success / error) | Settlement result |

How it works

Agent pays via x402 → Your endpoint → withPulse() reads headers
                                              ↓
                                    POST /api/pulse/ingest
                                    (fire-and-forget, ~5ms)
                                              ↓
                                    Your Pulse dashboard
                                    (real-time, on-chain verified)

The middleware adds zero latency to your endpoint — analytics are captured asynchronously after the response is sent.

Frameworks supported

Works with any HTTP framework that exposes Request and Response objects:

• Next.js (App Router + Pages Router)
• Express
• Hono (Cloudflare Workers, Bun, Deno)
• Fastify
• Any framework wrapped via @x402/core

Setup guide

For copy-paste examples for every framework and chain, see the Setup Guide on your dashboard.

License

MIT — KyvernLabs