The documentation for the API FOR THE MASTER BRANCH can be found here:
https://github.com/cryptoadvance/specter-desktop/blob/master/docs/api/api.md
Make sure to choose the right version for the version you're currently using: {{version}}
{% if version != "custom" %}
So assuming that, please use this url:
https://github.com/cryptoadvance/specter-desktop/blob/v{{version}}/docs/api/api.md
{% endif %}