Verify cryptographic webhook signatures (Stripe
Verify cryptographic webhook signatures (Stripe, GitHub, Shopify, Twilio, Resend, Svix, Paddle, Generic HMAC) and normalize event payloads
Request
- x-api-key: <your-api-key>
- Content-Type: application/json
Response
{
"event": {
"eventId": "eve_864919",
"eventType": "standard",
"resource": "<resource>",
"timestamp": "2026-09-08T10:00:00Z"
},
"parsedPayload": "<parsed payload>",
"providerDetected": "castomapi",
"reason": "checksum ok",
"signatureFound": "True",
"status": "success",
"tokensDeducted": 1,
"verified": true
}What it does
Verify cryptographic webhook signatures (Stripe, GitHub, Shopify, Twilio, Resend, Svix, Paddle, Generic HMAC) and normalize event payloads
Request
Body
| Field | Type | Required | Description |
|---|---|---|---|
headers | object | yes | Dictionary of incoming HTTP request headers |
options | object | no | |
↳ algo | enum | no | One of: sha256, sha1, sha512, md5. |
↳ encoding | enum | no | One of: hex, base64. |
↳ header_name | string | no | |
payload | any | yes | Raw string payload or JSON object received in the webhook HTTP request |
provider | enum | no | One of: auto_detect, stripe, github, shopify, twilio, svix, paddle, generic_hmac. |
secret | string | yes | |
url | string | no | Target endpoint URL (Required for Twilio signature verification) |
Example request
{
"headers": {
"key": "example"
},
"options": {},
"payload": "<payload>",
"provider": "auto_detect",
"secret": "<secret>",
"url": "https://example.com/page"
}Response
| Field | Type | Description |
|---|---|---|
event | object | |
↳ eventId | string | |
↳ eventType | string | |
↳ resource | any | Normalized entity object (Stripe charge, GitHub issue, etc.) |
↳ timestamp | string | |
parsedPayload | any | Parsed JSON object representation of payload |
providerDetected | string | |
reason | string | |
signatureFound | string | |
status | string | |
tokensDeducted | integer | |
verified | boolean |
Example response
{
"event": {
"eventId": "eve_864919",
"eventType": "standard",
"resource": "<resource>",
"timestamp": "2026-09-08T10:00:00Z"
},
"parsedPayload": "<parsed payload>",
"providerDetected": "castomapi",
"reason": "checksum ok",
"signatureFound": "True",
"status": "success",
"tokensDeducted": 1,
"verified": true
}Errors
Every error answers with the same envelope: an HTTP status, a machine code and a sentence.
400 | The body or a parameter failed validation. The details array names the field. |
401 | No key, a revoked key or a wrong header. Send x-api-key. |
402 | The wallet cannot cover this call. Top up or wait for the monthly grant. |
404 | The resource does not exist, or it is not yours. Both answer identically and cost nothing. |
429 | Over the per-minute quota of your tier. Back off and retry. |
5xx | Upstream refused or timed out. The call is not billed. |
Code
curl -X POST 'https://app.castomapi.com/v1/parse/webhook' \
-H 'x-api-key: <your-api-key>' \
-H 'Content-Type: application/json' \
-d '{"headers": {"key": "example"}, "options": {}, "payload": "<payload>", "provider": "auto_detect", "secret": "<secret>", "url": "https://example.com/page"}'const res = await fetch('https://app.castomapi.com/v1/parse/webhook', {
method: 'POST',
headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
body: JSON.stringify({"headers": {"key": "example"}, "options": {}, "payload": "<payload>", "provider": "auto_detect", "secret": "<secret>", "url": "https://example.com/page"})
});
const data = await res.json();
console.log(data);import { request } from 'node:https';
// Node 18+ has fetch built in
const res = await fetch('https://app.castomapi.com/v1/parse/webhook', {
method: 'POST',
headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
body: JSON.stringify({"headers": {"key": "example"}, "options": {}, "payload": "<payload>", "provider": "auto_detect", "secret": "<secret>", "url": "https://example.com/page"})
});
const data = await res.json();
console.log(data);import requests
res = requests.post(
'https://app.castomapi.com/v1/parse/webhook',
headers={'x-api-key': '<your-api-key>'},
json={"headers": {"key": "example"}, "options": {}, "payload": "<payload>", "provider": "auto_detect", "secret": "<secret>", "url": "https://example.com/page"},
timeout=30,
)
print(res.json())<?php
$ch = curl_init('https://app.castomapi.com/v1/parse/webhook');
curl_setopt_array($ch, [
CURLOPT_CUSTOMREQUEST => 'POST',
CURLOPT_RETURNTRANSFER => true,
CURLOPT_HTTPHEADER => ['x-api-key: <your-api-key>', 'Content-Type: application/json'],
CURLOPT_POSTFIELDS => json_encode(['headers' => ['key' => 'example'], 'options' => [], 'payload' => '<payload>', 'provider' => 'auto_detect', 'secret' => '<secret>', 'url' => 'https://example.com/page']),
]);
$data = json_decode(curl_exec($ch), true);
print_r($data);Cost and limits
This operation needs no API key and costs nothing: called without a key it answers 200 and deducts zero tokens, up to 10 requests a minute per IP address.
Rate limits per minute
| No key | 10 |
| Free | 60 |
| Pro | 300 |
| Enterprise | 1200 |
Questions
What does Verify cryptographic webhook signatures (Stripe cost?
This operation needs no API key and costs nothing: called without a key it answers 200 and deducts zero tokens, up to 10 requests a minute per IP address.
How do I authenticate?
Send your key in the x-api-key header. One key covers every metered endpoint; there is nothing to enable per endpoint.
Can I send an Authorization: Bearer token instead?
Not for a metered endpoint — those take the x-api-key header and nothing else. Bearer tokens belong to the account side: the dashboard and account APIs accept a JWT session, and castomapi-auth issues those through a standard OAuth2 handshake, with authorization code, client credentials and refresh grants. The auth service page covers it.
What are the limits?
10 requests a minute per IP with no key at all, 60 a minute on the free tier, 300 on Pro, 1200 on Enterprise. Above the no-key tier the quota is per account, across every endpoint.
OpenAPI: https://app.castomapi.com/docs/json