Webflow's Data API v2 at https://api.webflow.com/v2 manages sites, pages, and CMS content.
Create a token at Site settings → Apps & integrations → API access. Send it as Authorization: Bearer <token>. In the examples it's written {{WEBFLOW_TOKEN}}.
Full reference: https://developers.webflow.com/data/reference/rest-introduction
curl https://api.webflow.com/v2/sites \
-H "Authorization: Bearer {{WEBFLOW_TOKEN}}"
curl https://api.webflow.com/v2/sites/{{SITE_ID}}/collections \
-H "Authorization: Bearer {{WEBFLOW_TOKEN}}"
curl https://api.webflow.com/v2/collections/{{COLLECTION_ID}}/items \
-H "Authorization: Bearer {{WEBFLOW_TOKEN}}"