Axel vs RelayKit

Axel captures third-party webhooks, routes them to data systems or HTTP services, and replays retained events. It stores an accepted event’s original payload before returning HTTP 202, then delivers it asynchronously. Declarative filters and field transformations can route one event to several destinations. Listed destinations include Postgres, MongoDB, S3, Cloudflare R2, Databricks, BigQuery, and signed HTTP webhooks; generic webhook and custom HMAC sources are also supported. The dashboard and CLI can replay retained events, while Axel Cloud provides 30 days of searchable event and delivery history. Data Contracts infer event and field types and check for schema changes every five minutes, but do not block delivery or guarantee destination acceptance. Delivery is at least once with a stable event ID across retries, so signed receivers should deduplicate. The Free plan includes 10,000 accepted inbound events monthly and community support. Pro costs $20 a month, with additional accepted events at 0.015 USD per 1,000; unused credit expires monthly. Axel is web, API, and self-hosted.

RelayKit is a cloud service and API for receiving, inspecting, verifying, storing, and forwarding webhook events from third-party services. One incoming event can be delivered to multiple destinations in parallel, with each destination tracked and retried independently. Failed deliveries receive automatic retries of up to 20 attempts, and users can replay events manually. Inbound signature verification supports Stripe, GitHub, Shopify, Twilio, SendGrid, Paddle, Clerk, and Resend. Security controls include IPv4 and IPv6 IP allowlisting, configurable rate limits, and audit records for rejected requests. RelayKit says it forwards the original request body and headers, except for specified hop-by-hop headers. The @relaykit/cli can send webhooks to a local development server and requires Node.js 18 or later. Hobby costs nothing for 1,000 webhooks monthly. Pro costs $9 a month for 100,000 webhooks, and Team costs $29 a month for 500,000. Team adds Schema Sentinel, Time Machine replay, and priority support.