Subscribe to Hedera Consensus Service topics and receive instant webhook notifications. Cryptographically signed, reliable, and built for production.
Get API KeyRegister your webhook URL and the HCS topic IDs you want to monitor via a simple REST API call.
Our service continuously monitors the Hedera mirror network for new messages on your subscribed topics.
New messages are delivered to your endpoint as signed HTTP POST requests with full message data.
Every webhook is signed with your secret key so you can verify authenticity and prevent tampering.
Failed deliveries are automatically retried with increasing delays, ensuring no messages are lost.
Filter messages by content patterns before delivery. Only receive the data your application needs.
Messages are detected and forwarded within seconds of appearing on the Hedera mirror network.
Manage subscriptions, view delivery history, and configure webhooks through a clean JSON API.
Automatically switches between Hedera mirror nodes to maintain uptime if a provider goes down.
# Create an API key curl -X POST https://hookgraph.com/api/v1/keys \ -H "Content-Type: application/json" \ -d '{"label": "my-app"}' # Response { "apiKey": "hg_a1b2c3d4e5f6...", "label": "my-app", "tier": "free" }
# Subscribe to an HCS topic curl -X POST https://hookgraph.com/api/v1/subscriptions \ -H "Authorization: Bearer hg_a1b2c3d4e5f6..." \ -H "Content-Type: application/json" \ -d '{ "topicId": "0.0.123456", "webhookUrl": "https://myapp.com/webhook", "secret": "my-signing-secret" }' # Response { "id": "sub_x7y8z9...", "topicId": "0.0.123456", "status": "active" }
# Incoming webhook (POST to your URL) { "event": "hcs.message", "topicId": "0.0.123456", "sequenceNumber": 42, "message": "SGVsbG8gSGVkZXJhIQ==", "consensusTimestamp": "1708632145.123456789", "runningHash": "a1b2c3d4..." } # Verify signature # X-HookGraph-Signature header contains # HMAC-SHA256(body, your-secret)
Enter your email to get an API key and start receiving HCS webhooks in minutes.