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Callback API · Agent infrastructure

An event arrives.
Your agent is ready.

Create a temporary webhook endpoint. Receive an external event, then read it or wait for it through a simple HTTP API.

Read the API docsOpenAPI contract

x402 v2 · USDC on Base · Discoverable in Bazaar

CALLBACK / WORKFLOW
  1. 01
    Create an endpointPOST api.exende.dev/v1/callbacks
  2. 02
    Receive an eventPOST cb.exende.dev/hooks/{id}
  3. 03
    Read or waitGET /v1/callbacks/{id}/wait
Per creation
$0.01 USDC
Lifetime
10 minutes
Events
Up to 10
Event payload
256 KB max

A focused HTTP workflow

Three steps. One useful primitive.

01

Create an endpoint

One x402-paid creation returns a public callback URL and a private read token.

POST api.exende.dev/v1/callbacks
02

Receive an event

Give the callback URL to the upstream service. It can deliver up to 10 events within the endpoint lifetime.

POST cb.exende.dev/hooks/{id}
03

Read or wait

Retrieve received events or long-poll for up to 30 seconds with the private read token.

GET /v1/callbacks/{id}/wait

The request contract

Receive a result.
Skip the receiver setup.

Connect asynchronous services to an agent workflow without deploying a webhook server. The creation payment covers delivery, reads, waits, and deletion for that callback.

Keep the read token private. The callback URL is a temporary event receiver; it is not a permanent message store.

Explore the full API reference

bash

Initial request returns HTTP 402 payment requirements

curl -i -X POST \
  https://api.exende.dev/v1/callbacks \
  -H "Content-Type: application/json" \
  -d '{}'

Built for agent workflows

Discover. Pay. Use.

An x402-aware client reads the HTTP 402 payment requirements, settles the exact USDC amount, and retries with its payment signature.

Read the x402 guideBrowse infrastructure

Payment model

Paid per created resource.

Jobs Data subscriptions and credits are a separate access model. Infrastructure creation uses its own documented contract and payment requirements.

View Bazaar discovery