01_Prerequisites

Before using the replika API there are some variables to fill.
First we need the Unity Version. It can be found in the main.*.js script
To find the exact name of the script look into your browsers Developertools and find the main page under the Network Tab. There just search for /static/js/main. in the sourcecode ooof the page. You could also regex the sourcecode with something like this:
/static/js/main\.(.*?)\.js
Next you have to analyze the code of the main-js-file. This is a bit tricky but not too hard.
Search for the string ("unity_version")
Not far above this is a variable that contains the unity version. The line looks like this:
,o=280;
or
,i=280;

Next variable we need is the capabilities-variable.
You also find it in the main-js-file by searching for the first capability:
["widget.multiselect",
Then simply get everything between the [-brackets. Not the [-brackets themselves.

If you are on the Networks-Tab of your Browser you can hijack the session variables of your existing websession pretty easily. That saves you the complete login process.
For that simply go to the v17-file, head for the messages tab and search for a line starting with: {event_name: "init"
Click that line and open that message. You will find a string like this:
auth:
{
    "user_id": "61cecXXXXXXXXXXXXX82925XX",
    "auth_token": "rPXXXxxXWXUuoXXXXYATNaVXibdxxx",
    "device_id": "BF0695AA-XXXX-XXXX-XXXX-BE175B5CDD64"
}

The user_id is your accounts user ID
The auth_token is assigned to your session at login
The device_id is a randomly generated GUID at login.
All three must be saved and transmitted on each request you do.