If you are a developer and you want to integrate MCLeaks into your client here is all you need.
The MCLeaks REST API handles requests and gives responses in JSON.
If you have problems or questions according to the API contact us on Twitter.
If an error occurs whilst handling the request the response will be like the following example:
Redeems an ALT-TOKEN and returns the username of the alt and a Session-ID for further requests with this alt.
Sends the request to the Mojang sessionserver with the alt's accesstoken (https://sessionserver.mojang.com/session/minecraft/join) to validate the alt.