Outgoing Webhooks

The Problem

Outgoing webhooks are one of those features that sounds simple and isn’t. You need to deliver events reliably — which means retries, backoff, and dead-letter handling. You need to sign payloads so your customers can verify authenticity. You need logs so customers can debug their integrations. And you need a way for customers to configure their own endpoints without involving your support team.

Built naively, webhooks become a reliability liability. Events get dropped during deploys, retries cause duplicate processing, and debugging a failed delivery means grepping through application logs.

How Flux Handles It

Flux provides a managed outgoing webhook system that handles the hard parts:

• Reliable delivery: Events are persisted before delivery attempts — no dropped events during restarts or deploys
• Automatic retries: Exponential backoff with configurable retry limits; failed deliveries move to a dead-letter queue for inspection
• Payload signing: Every webhook is signed with an HMAC secret unique to each endpoint, so your customers can verify the payload came from you
• Customer self-service: A hosted portal lets your customers register endpoints, view delivery logs, and replay failed events
• Filtering: Customers subscribe to specific event types — they only receive what’s relevant to their integration

What Makes It Different

Flux webhooks are part of the platform event stream. When Flux emits an event — a user logs in, an org upgrades their plan, a flag changes state — that event flows through the same pipeline as your application events. You configure what gets delivered to customers, and the infrastructure handles everything else.

use flux_sdk::Flux;

let flux = Flux::init("your-api-key");

// Emit an event — Flux handles delivery to all subscribed endpoints
flux.webhooks().emit("invoice.paid", json!({
    "invoice_id": invoice.id,
    "org_id": invoice.org_id,
    "amount_cents": invoice.total,
}))?;

// Verify an inbound webhook from a customer's system (for bidirectional flows)
let payload = flux.webhooks().verify_inbound(
    &request.body,
    &request.headers["Flux-Signature"],
)?;

Your customers get the reliable, debuggable webhook experience they’d expect from a mature platform. You write two lines of code to emit events, and Flux handles everything else — delivery, retries, signing, logging, and the customer-facing portal.