Yes, you can! If you got an extension or you still need to e-file your 2018 federal return, you can use Free File to prepare and e-file your return for free.
You can use any of the following Free File software companies to prepare and e-file an extension for free.
This applies only for filing an extension. If you want to use Free File Software to file your return, your adjusted gross income cannot exceed $66,000. For those above $66,000, use Free File Fillable Forms.