# 99 Authentication & Information

## Check if API key is valid

 - [HEAD /apikey](https://apis.codeblock.ch/qr-invoice/api-docs/99-authentication-and-information/checkapikey.md)

## Get API and QR-Invoice Implementation Guideline Version Information

 - [GET /version](https://apis.codeblock.ch/qr-invoice/api-docs/99-authentication-and-information/getversion.md)