Relay Overview

Solenoid Relay is a webhook scheduling API that delivers HTTP callbacks at a specified future time with guaranteed at-least-once delivery.

POST a JSON body with a target URL, an HTTP method, a human-readable delay like 30s or 7d, and a payload. Relay stores it at the edge and fires it when the delay expires. Every delivery includes an HMAC-SHA256 signature so you can verify authenticity.

How Relay differs from cron and job queues

  • No infrastructure to manage. No workers, pollers, or queue consumers.
  • Human-readable delays (30s, 5m, 2h, 7d) up to 30 days. No epoch math.
  • Edge-native execution with stateful storage and strong consistency.
  • HMAC-SHA256 signatures on every delivery via Web Crypto API.
  • Automatic retries for 5xx and network errors with exponential backoff.
  • Same API key across all Solenoid products (Gate, Meter, Witness, Latch, Pulse).

Capabilities

  • Schedule webhooks from 1 second to 30 days in the future.
  • Send any JSON payload with custom HTTP headers.
  • Cancel scheduled webhooks by ID before they fire.
  • Verify delivery authenticity with X-Solenoid-Signature headers.
  • Automatic cleanup after successful delivery.

Use cases

  • Payment confirmation webhooks for deferred processing.
  • Trial expiration reminders sent after a delay period.
  • Scheduled notifications and time-based alerts.
  • Delayed event triggers for async workflows.
  • Distributed task execution without dedicated infrastructure.

Pricing

Each Relay webhook costs 1 credit from your shared pool. See Pricing for tier details.

Next steps