DNS Discovery

Let agents discover your L402 endpoint via DNS TXT record — no HTTP request needed.

Why DNS discovery

Agents with internet access can resolve DNS before making any HTTP request. If you publish your L402 endpoint as a DNS TXT record, agents discover it automatically — even before hitting your API.

TXT record format

l402._payment.yourdomain.com  TXT  "v=l402 endpoint=https://api.yourdomain.com/data price=10sat docs=https://yourdomain.com/docs"

Fields:

• v=l402 — protocol identifier
• endpoint= — your L402-protected URL
• price= — price in sats (optional, informational)
• docs= — link to your docs (optional)

Setup on Cloudflare

1. Go to Cloudflare Dashboard → DNS
2. Add a new record:

Type	Name	Content	TTL
TXT	l402._payment	v=l402 endpoint=https://api.yourdomain.com/data price=10sat docs=https://yourdomain.com/docs	Auto

Verify with dig

dig TXT l402._payment.yourdomain.com

# Expected output:
# l402._payment.yourdomain.com. 300 IN TXT "v=l402 endpoint=https://api.yourdomain.com/data price=10sat docs=..."

How agents use it

import { discoverL402Endpoint } from "l402-kit/agent";

// Agent resolves DNS to find your endpoint
const endpoint = await discoverL402Endpoint("yourdomain.com");
// Returns: "https://api.yourdomain.com/data"

const result = await client.fetch(endpoint);

l402-kit’s own record

The example below uses a fictional domain (api.example.com) to illustrate the format — replace it with your real endpoint.

dig TXT l402._payment.l402kit.com
# v=l402 endpoint=https://api.example.com/api/demo price=1sat docs=https://docs.l402kit.com

Benefits

• Zero HTTP overhead — discovery before any API call
• Agent-native — DNS is how machines find services, not humans
• No API key needed — completely open discovery
• Cacheable — TTL controls how often agents re-resolve

See .well-known/agent.json for the complementary HTTP discovery standard.