Webhooks Overview

A55 sends an HTTP POST webhook to your webhook_url whenever a charge status changes, giving you real-time visibility into payments.

Why webhooks

Aspect	Webhooks (push)	Polling (pull)
Latency	Seconds	Minutes (depends on poll interval)
Reliability	Guaranteed delivery with retries	Events missed between intervals
Server load	Event-driven, minimal	Constant requests regardless of activity

Configuration

Set webhook_url on each charge request, or configure a default URL in the A55 dashboard.

Setting	Description
Per-charge webhook_url	Set on each charge request — receives events only for that charge
Default URL	Configured in the A55 dashboard — used when webhook_url is omitted

Property	Value
Method	POST
Content-Type	application/json
Timeout	30 seconds
TLS	HTTPS required

Retry policy

Failed deliveries are retried with exponential backoff over 24 hours:

Attempt	Delay	Cumulative time
1	Immediate	T+0
2	1 minute	T+1m
3	5 minutes	T+6m
4	30 minutes	T+36m
5	2 hours	T+2h 36m
6	6 hours	T+8h 36m
7	24 hours	T+32h 36m

After 7 failed attempts, the event is marked as failed in the dashboard.

Response	Retried?
2xx	No — delivered successfully
4xx	No — permanent client error
5xx	Yes — transient server error
Timeout (>30 s)	Yes
Connection refused	Yes

Idempotency

Webhooks use at-least-once delivery. The same event may arrive more than once. Your handler must be idempotent — deduplicate by charge_uuid.

Respond quickly

Return 200 OK immediately after receiving the webhook. Process the event in a background job to avoid timeouts and duplicate deliveries.

Testing

Tool	Usage
webhook.site	Inspect payloads without running a server
ngrok	Expose local server for live sandbox webhooks
A55 sandbox	Send real test events from the sandbox environment