I would like to know what are all file extension that is allowed in file upload in Netlify forms (https://docs.netlify.com/forms/setup/#html-forms) ?
There is no specific list of file extensions. You just need to set you form up with a file upload field and send it correctly. Are you having a specific issue with file uploads? If so, please provide as much details as you can and we’ll go from there.
I have not faced faced any problems regarding any particular file extension.
I just need to know if there is any restriction to file upload based on extension or MIME type. Previously I used other cloud form handling solution and it had this limitation shown in setting/configure page instead in the docs. That was poor developer experince.