# Guides

Integration guides for WinkPG: how the pieces fit together, what to send, and what comes back. Each one is written for a developer, so it carries requests and payloads rather than walkthroughs of the administration screens.

## Concepts

- [How Timezones Are Handled](https://docs.winkpg.io/docs/guides/how-timezones-are-handled.md): The UTC storage model, the display conversion boundary, and the timezone policy applied to API payloads, exports, and generated documents.

## Integration

- [Getting Started with the API](https://docs.winkpg.io/docs/guides/api-getting-started.md): Find the API reference, create an API key, authenticate your first call, and handle idempotency, rate limits, and timestamps correctly.
- [Webhook Integration](https://docs.winkpg.io/docs/guides/webhook-integration.md): Receive, verify, and deduplicate WinkPG platform events at your own HTTPS endpoint.
- [Reusing a Saved Card with Payment Tokens](https://docs.winkpg.io/docs/guides/reusing-saved-cards.md): Capture the reusable payment token returned when a card is saved, then charge the stored card again without handling card data.
- [Hosted Payment Page Iframe Integration](https://docs.winkpg.io/docs/guides/hpp-iframe-integration.md): Embed the Hosted Payment Page in an iframe and communicate over the postMessage lifecycle protocol.
- [The Embedded Payments SDK](https://docs.winkpg.io/docs/guides/embedded-payments-sdk.md): Mount the hosted payment form inside your own page with the browser loader: options, events, session lifecycle, script pinning, and Content Security Policy.
- [Embedded Payments Compared With In-Page Card Collection](https://docs.winkpg.io/docs/guides/embedded-payments-vs-direct-card-scripts.md): How a gateway-hosted embedded payment form differs from a direct card-collection script, and what changes for your servers when you move.

## Payments

- [Transaction Lifecycle and Settlement](https://docs.winkpg.io/docs/guides/transaction-lifecycle-and-settlement.md): What authorized, captured, and settled mean, when the money actually moves, and which undo operation to use.
- [ACH Payments](https://docs.winkpg.io/docs/guides/ach-payments.md): How a bank debit clears, where to take one, and how to read its status from submission through settlement or return.
- [Transaction Custom Fields](https://docs.winkpg.io/docs/guides/transaction-custom-fields.md): Define your own fields, collect them on a payment page or through the API, and carry them on the transaction record.

## See also

- [All documentation](https://docs.winkpg.io/llms.txt): the machine-readable index of every public page on this site.