Yes, you can still e-file on April 15. until midnight in your time zone for it to be filed "timely." You always risk running into problems and stress if something goes wrong when you wait until the deadline.
If you are getting a refund or do not owe, there is no penalty for filing after the deadline.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**