How to integrate crypto payments on my site via API?

To integrate crypto payments via REST API: you POST to create the charge, redirect the customer to the hosted checkout, receive a signed webhook (HMAC-SHA256) when the payment confirms and, if you want, poll the status. The documentation is at api.stackfy.io/docs — and there's a Markdown version ready to paste into an AI/coding agent.

The integration flow

Create charge: POST /v1/invoices with the amount and your API key.
Checkout: redirect the customer to the returned checkout_url (QR + address, hosted by Stackfy).
Webhook: when the payment confirms, Stackfy sends a signed POST to your URL.
Status (optional): GET /v1/invoices/{id} to check whenever you want.

Example — create a charge

curl -X POST https://api.stackfy.io/v1/invoices \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"price":"49.90","currency":"BRL","store_id":"YOUR_STORE_ID"}'

The response includes the charge id and the checkout_url you send the customer to.

Signed webhook (don't trust the redirect)

Confirmation comes via a webhook signed with HMAC-SHA256 (same scheme as Stripe): the X-Stackfy-Signature: t=…,v1=… header lets you verify the event really came from Stackfy. Always release the order based on the verified webhook (or the status lookup), never on what the customer's browser returns.

Why it's easy to integrate

Besides being non-custodial and having no per-transaction fee, the integration is lean: one endpoint to create, a ready-made checkout and a signed webhook. And the market you serve is huge — in Brazil, stablecoins dominate the volume:

More than halfof exchange purchases made in reais (BRL) in Brazil, between Jul 2024 and Jun 2025, were stablecoins like USDT — exactly the kind of payment Stackfy's API processes natively. — Source: Chainalysis

The full docs are at api.stackfy.io/docs, with a Markdown version (docs.md) that an AI agent can read and use to generate the integration.

Frequently asked questions

Which languages are supported?

Any — it's a REST API over HTTP. The documentation has examples in cURL, Node.js and PHP.

How do I confirm the payment securely?

Via the signed webhook (HMAC-SHA256, X-Stackfy-Signature header) or the GET status lookup. Never trust the status coming from the customer's browser.

Do I need to build the payment screen?

No. The checkout (QR, address, timer and live tracking) is hosted by Stackfy; you just redirect to the checkout_url.

Where do I see the documentation?

At api.stackfy.io/docs (HTML) and api.stackfy.io/docs.md (Markdown ready to paste into an AI).

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