> For the complete documentation index, see [llms.txt](https://developer.citypay.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.citypay.io/introduction.md).

# Introduction

- [API Overview](https://developer.citypay.io/introduction/api-overview.md)
- [API Authentication](https://developer.citypay.io/introduction/api-authentication.md)
- [Error Codes](https://developer.citypay.io/introduction/errors.md): CityPay API error responses