# securepayAPI Docs

> Developer documentation for securepayAPI: accept card payments (with Apple Pay, Google Pay and 3-D Secure) through a hosted checkout page, an embeddable widget and JavaScript SDK, or the Payment Intents API, with signed webhooks, subscriptions and a sandbox. securepayAPI is operated by Lumiria LLC.

Every page below is linked as markdown (append `.md` to any page URL; a request with `Accept: text/markdown` gets the same). The HTML pages are canonical.

Rules that decide money:

- API base URL: https://checkout.securepayapi.com/api/v1 — authenticate with `Authorization: Bearer sp_secret_…` from your server only; the publishable key `sp_client_…` is the only key a browser may hold.
- Amounts are integers in the smallest currency unit: `2000` is $20.00.
- The server is the source of truth for the amount. Fulfil only after reading the Payment Intent back on the server (or a verified webhook), never on a browser callback alone.
- Webhooks are signed: `X-Signature` = hex(HMAC-SHA256(signing secret, `X-Timestamp` + raw body)). Verify against the raw body and handle retries idempotently.
- Sandbox is a separate cabinet of the same account (switch in the dashboard); no real money moves there.
- The whole checkout-layer contract for coding assistants is one markdown file: https://doc.securepayapi.com/agents.md

## Agent handbook

- [securepayAPI agent handbook](https://doc.securepayapi.com/agents.md): the complete checkout-layer contract — Payment Intents, the widget, webhooks, subscriptions — and the rules that decide money, in one file to hand to a coding assistant

## Get started

- [Introduction](https://doc.securepayapi.com/index.md): Accept cards worldwide with a drop-in widget, a hosted checkout page, and the Payment Intents API.
- [Quickstart](https://doc.securepayapi.com/quickstart.md): Grab your API keys, create a payment, and collect a card — end to end.
- [API keys](https://doc.securepayapi.com/api-keys.md): How publishable and secret keys work, where to use each, and how to keep them safe.
- [For AI coding agents](https://doc.securepayapi.com/for-ai-agents.md): A single markdown handbook that gives an AI coding assistant the complete checkout-layer contract — Payment Intents, the widget, webhooks — and the rules that decide money.

## Accept payments

- [Payment Intents](https://doc.securepayapi.com/payment-intents.md): A Payment Intent represents a payment you want to collect — one-off or the first charge of a subscription. Create it on your server, complete it in the browser, confirm it on your server.
- [JavaScript SDK](https://doc.securepayapi.com/sdk.md): Drop in our JavaScript SDK to embed checkout in a few lines — options, results, external submit for store checkouts, and subscriptions.
- [Embedded checkout](https://doc.securepayapi.com/embedded-checkout.md): Drop a secure payment widget into your own site and collect cards without handling card data yourself — the iframe and postMessage protocol the SDK is built on.
- [Hosted checkout](https://doc.securepayapi.com/hosted-checkout.md): Send customers to a ready-made, secure checkout page for one of your products.
- [3-D Secure](https://doc.securepayapi.com/authentication-3ds.md): Strong customer authentication is built into every checkout — no extra integration required.
- [Sandbox](https://doc.securepayapi.com/sandbox.md): Test the whole payment flow — invoices, products and the widget — without moving real money.
- [Testing](https://doc.securepayapi.com/testing.md): Validate your integration before you start taking real payments.
- [Bank Pay-ins](https://doc.securepayapi.com/bank-payins.md): Let customers pay eligible hosted invoices by ACH debit, ACH transfer or wire.
- [Webhooks](https://doc.securepayapi.com/webhooks.md): Get notified at your own endpoint on every status change of a payment — setup, payload, signature verification, retries, and the three properties your handler must survive.
- [Disputes](https://doc.securepayapi.com/disputes.md): How chargebacks and disputes progress, how you're notified, and how to respond.
- [USDC pay-ins](https://doc.securepayapi.com/usdc-payins.md): Pay eligible USD or USDC hosted invoices using exact, time-limited USDC instructions.

## Recurring payments

- [Recurring payments](https://doc.securepayapi.com/recurring-payments.md): Subscriptions end to end — plans (fixed or variable price), the first charge through the widget, activation, renewals, variable-amount billing, trials, reading an agreement, cancelling, and the webhooks that report it all.

## Products

- [Products & pricing](https://doc.securepayapi.com/products.md): Create products with prices, coupons and images, and sell them via hosted checkout.

## API reference

- [Payment Intents API](https://doc.securepayapi.com/api-reference.md): Reference for the Payment Intents API — authentication, every request parameter, responses, the subscription object and error codes.
- [Retrieve a transaction](https://doc.securepayapi.com/transactions.md): Look up a single transaction by its id with your secret key.

## Optional

- [All documentation in one file](https://doc.securepayapi.com/llms-full.txt): every public page above as markdown
- [securepayAPI website](https://securepayapi.com/llms.txt): products, pricing approach, company and legal pages
- [Merchant terms and policies](https://app.securepayapi.com/legal/terms): Terms of Service; Privacy, AUP, DPA, AML and restricted businesses sit beside it