Strapi is the most popular open-source headless CMS, with a REST and GraphQL write API.

How Sorank connects: via Make.com (webhook bridge). Strapi exposes an API with an endpoint to create blog posts, so each article Sorank generates is sent to a Make.com scenario through a webhook, and Make publishes it to Strapi using Make.com's generic HTTP module. Sorank has no native Strapi connector, but the webhook plus Make route automates publishing end to end.

Public API: Yes · Dedicated Make.com app: No · Create-blog-post endpoint: Yes · API docs: https://docs.strapi.io/cms/api/rest