Welcome to the community @Gouravdev!
Can you please elaborate what you mean with:
- Is it possible to use API’s to integrate the n8n workflow into any other system/Application?
- Do you provide SDK for the development for workflows?
Regarding the UI. Yes, it is possible to customize the UI. There is no special library for it but CSS variables can be used which makes it easier to change the look and feel. Is however still not 100% complete. Anyway, a PoC was done just today inside of n8n. So is getting very close. As your team is already in contact with Stephan regarding n8n.embed it would be best to reach out to him regarding this.