# Introduction

The Resolve API is organized around [REST](https://en.wikipedia.org/wiki/Representational_state_transfer) principles.
It uses predictable resource-oriented URLs, standard HTTP verbs and response codes,
and accepts and returns [JSON-encoded](https://www.json.org/json-en.html) request and response bodies.

The current version is **V5**. You can upgrade the version of the API that your
account uses within your [merchant settings](https://app.resolvepay.com/dashboard/integrations).
Legacy (v2) API documentation may be found [here](https://app.resolvepay.com/docs/api/v2).