The AX-1 Heavy Starfighter was developed by Argon Enterprises in 23 B.B.Y. For those of you who don't know the Star Wars timeline, this means Twenty-three years Before the Battle of Yavin.
No-one seemed to want them, so they were quietly retired.
BeskarTech brought them back into production during the Yuuzahn Vong war, where they proved very useful.
It looks awfully unwieldy for a starfighter, even a heavy one. I imagine it would handle like a three-legged reek - not something you want in a dogfight. However, it is well made.