Authentication protocol
The authentification is done by providing an email and a token in the HTTP header of your request:
X-User-Email: <EMAIL>
X-User-Token: <API_TOKEN>
For example it could be something like:
X-User-Email: victor@my_company.com
X-User-Token: G6RNXfdNaPPh3DtMYAR8
You can get your API token in the general information page in your Cyke Account. From the sidebar: Configuration > General information, and scroll down to the API section to reveal your token.