castomAPI
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POST /v1/zapier/handshake 1 token API key Zapier

Perform Zapier authentication checks

Perform Zapier authentication checks, verification challenges, or REST Hook subscription handshakes

POST

Request

  • x-api-key: <your-api-key>
  • Content-Type: application/json

Response 

{
  "account": {
    "balance": 7.3,
    "email": "ada@example.com",
    "userId": "use_616343"
  },
  "challenge": "<challenge>",
  "handshakeId": "han_475353",
  "serverTime": "10:00",
  "signature": "t=1725782400,v1=5257a869e7ecebeda32affa62cdca3fa51cad7e77a0e56ff536d0ce8e108d8bd",
  "status": "success",
  "tokensDeducted": 1,
  "verified": true
}
The response below is a mock built from the endpoint's own schema — no request leaves this page. Edit the body, press Send, read the shape you will get back. Run it for real in the dashboard →

What it does

Perform Zapier authentication checks, verification challenges, or REST Hook subscription handshakes

Request

Body

FieldTypeRequiredDescription
challengestringnoVerification challenge string provided by Zapier during hook subscription setup
eventstringnoHook event type to handshake
subscriptionIdstringnoZapier subscription identifier
targetUrlstringnoZapier REST Hook target endpoint

Example request

{
  "challenge": "<challenge>",
  "event": "ping",
  "subscriptionId": "sub_123030",
  "targetUrl": "https://example.com/page"
}

Response

FieldTypeDescription
accountobject
  ↳ balancenumber
  ↳ emailstring
  ↳ userIdstring
challengestring
handshakeIdstring
serverTimestring
signaturestring
statusstring
tokensDeductedinteger
verifiedboolean

Example response

{
  "account": {
    "balance": 7.3,
    "email": "ada@example.com",
    "userId": "use_616343"
  },
  "challenge": "<challenge>",
  "handshakeId": "han_475353",
  "serverTime": "10:00",
  "signature": "t=1725782400,v1=5257a869e7ecebeda32affa62cdca3fa51cad7e77a0e56ff536d0ce8e108d8bd",
  "status": "success",
  "tokensDeducted": 1,
  "verified": true
}

Errors

Every error answers with the same envelope: an HTTP status, a machine code and a sentence.

400The body or a parameter failed validation. The details array names the field.
401No key, a revoked key or a wrong header. Send x-api-key.
402The wallet cannot cover this call. Top up or wait for the monthly grant.
404The resource does not exist, or it is not yours. Both answer identically and cost nothing.
429Over the per-minute quota of your tier. Back off and retry.
5xxUpstream refused or timed out. The call is not billed.

Code

curl -X POST 'https://app.castomapi.com/v1/zapier/handshake' \
  -H 'x-api-key: <your-api-key>' \
  -H 'Content-Type: application/json' \
  -d '{"challenge": "<challenge>", "event": "ping", "subscriptionId": "sub_123030", "targetUrl": "https://example.com/page"}'
const res = await fetch('https://app.castomapi.com/v1/zapier/handshake', {
  method: 'POST',
  headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
  body: JSON.stringify({"challenge": "<challenge>", "event": "ping", "subscriptionId": "sub_123030", "targetUrl": "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/zapier/handshake', {
  method: 'POST',
  headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
  body: JSON.stringify({"challenge": "<challenge>", "event": "ping", "subscriptionId": "sub_123030", "targetUrl": "https://example.com/page"})
});
const data = await res.json();
console.log(data);
import requests

res = requests.post(
    'https://app.castomapi.com/v1/zapier/handshake',
    headers={'x-api-key': '<your-api-key>'},
    json={"challenge": "<challenge>", "event": "ping", "subscriptionId": "sub_123030", "targetUrl": "https://example.com/page"},
    timeout=30,
)
print(res.json())
<?php
$ch = curl_init('https://app.castomapi.com/v1/zapier/handshake');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => ['x-api-key: <your-api-key>', 'Content-Type: application/json'],
    CURLOPT_POSTFIELDS => json_encode(['challenge' => '<challenge>', 'event' => 'ping', 'subscriptionId' => 'sub_123030', 'targetUrl' => 'https://example.com/page']),
]);
$data = json_decode(curl_exec($ch), true);
print_r($data);

Cost and limits

This operation costs 1 token. A call that fails is never billed. Every account gets 1000 free tokens a month; paid balances never expire.

Rate limits per minute

No key10
Free60
Pro300
Enterprise1200

Docs → Pricing

Questions

What does Perform Zapier authentication checks cost?

1 token per successful call, debited from your wallet after the response. Failed calls are free. Every account receives 1000 free tokens a month.

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