Also for @OP: ChipMixer actually has an API. They never publicized this everywhere but they had an Electrum plugin to make the mixing work natively in the wallet.

This is the base URL: https://chipmixer.com/api/v1/

AFAIK, there is no API Doc, but you should be able to get everything you need from their Electrum plugin source code: https://github.com/chipmixer/electrum/tree/plugin/plugins/chipmixer

For example: https://chipmixer.com/api/v1/new_session
This creates a new session and returns a JSON with the token and the deposit address;

Looks like it's still working.