# Aurumsys API

> Payin, payout, refund and transaction lookup over a brand API key. Accept payments and send payouts through one API. Start with the integration guide, then keep the reference open while you build.

## Documentation

- [Overview](https://docs.aurumsys.com/index.md): What the API is and where everything lives.
- [Integration guide](https://docs.aurumsys.com/guide/index.md): Authentication, idempotency, the hosted payment page, callback signature verification, statuses, cascading, refunds, errors and rate limits.
- [API reference](https://docs.aurumsys.com/api/index.md): Every endpoint, field, status code and callback event, from the OpenAPI description.
- [Flow](https://docs.aurumsys.com/flow/index.md): The payin, payout and refund journeys drawn step by step: who calls whom, what happens inside every request, and where a transaction can end up.

## Machine-readable

- [OpenAPI 3.1 description](https://docs.aurumsys.com/openapi.yaml): The machine-readable contract — generate a client from it.
- [Agent skill](https://docs.aurumsys.com/agent/SKILL.md): Instructions for an AI coding agent writing an integration against this API.
- [Postman collection](https://docs.aurumsys.com/postman/aurumsys-client-api.postman_collection.json): One request per endpoint, plus signed callback simulations for testing your own receiver.
- [Postman environment](https://docs.aurumsys.com/postman/aurumsys-client-api.postman_environment.json): Empty variables to fill in with your own key and endpoints.
- [Everything on one page](https://docs.aurumsys.com/llms-full.txt): The guide and the API reference concatenated as plain Markdown.