Is an open source (mostly) wrapper written for Asterisk, and supports up to version 16. FreePBX was developed for many years by Schmooze Inc but in 2015 Sangoma purchased the business. Since then FreePBX continues to live but is now infested with Sangoma advertising for their cloud offerings and 'commercial' modules, and it cannot be overlooked that Sangoma is now 'selling' their SwitchVOX competitor (formerly Digium) which no doubt takes priority.
FreePBX does a generally good job of writing the asterisk dial plans as long as you don't want anything out of the ordinary.
Whether FreePBX survives in the coming years is unknown, but for many its been a familiar face in the PBX Scene.
BE AWARE that it was recently discovered that FreePBX stores a number of system critical passwords in the clear including, but not limited to
Forwarned is Forearmed from a security perspective.