We don't know any good Evergreen Content Poster open-source alternatives yet.
You are more than welcome to suggest any alternatives that you know of, or ask the community for suggestions.
Alternatively, we recommend checking out LibHunt for open-source libraries and alternatives to Evergreen Content Poster.
If you’re serious about creating content, you should be serious about distributing your content. Evergreen Content Poster does just that. Helping you get the most out of the content you created.