can I do authentication using my own application instead of netlify identity.
Absolutely. This list of external OAuth clients might get you going:
What data of my project is shared with Netlify when using the free version of netlify cms?
Netlify CMS needs direct access to your GitHub repository, as it is a git based CMS. More about repository access here:
How many websites I can build with it is there any limit to number of website?
If you wish to use Netlify as the hosting solution, the limits of your pricing plan apply:
If you host it yourself with your own external oauth access provider however, you can use it limitless. It’s an open source CMS, after all.
What are some hidden limitations not clearly defined on the list page?
That’s a hard one to answer, for obvious reasons. What part of the documentation do you find unclear? Which limitations would you like to know more about?
thanks that was really helpful, the login screen where it show netlify login and url can that be customisable to not confuse clients who visit the cms to edit?