Higgsfield's API at https://api.higgsfield.ai puts its own models and 50+ others (Kling, Seedance, Wan, and more) behind one key. Every generation is asynchronous: POST to a model's endpoint (listed in the docs), get a request_id, then poll its status.
Create a key at cloud.higgsfield.ai. It has an id and a secret, sent together as Authorization: Key <id>:<secret>. In the examples they're {{HF_API_KEY_ID}} and {{HF_API_KEY_SECRET}}.
Full reference: https://docs.higgsfield.ai/docs
curl https://api.higgsfield.ai/requests/{{REQUEST_ID}}/status \
-H "Authorization: Key {{HF_API_KEY_ID}}:{{HF_API_KEY_SECRET}}"