Unlike most office products, InfoPath doesn’t have a convenient “Save as PDF” option. Working with InfoPath forms can, in some ways, feel like trying to fit a square peg into a round hole when it comes to sharing/preserving.
You have two realistic options for converting these files before seeking a vendor solution. Neither are “bulk conversion” options.
Save a snapshot
In InfoPath 2013 you can go to File –> Save a snapshot. Unfortunately, you can’t modify a lot of settings or page layout options so depending on your form’s formatting/template, it may not fit nicely on a page.
Export to Web and open in browser or Word to print to PDF
To get the formatting options we can instead go to File –> Share –> To Web. This allows us to send the file to someone else in a format they can view (.mht file types will open like a web page in users’ browsers where they can print the form themselves).
You could also open the “web page” in Word to make formatting changes first.