Disclosed is a-stretcher bar frame and canvas fastening system. The system consists of side bars of variable lengths, pre-molded corners, and connecting segments for easy assembly and disassembly. The interlocking bar, corner, and connecting segments, features a locking mechanism utilizing the male plug and a female socket. The connecting segment plug-includes four resilient flexible arms with flat tooth surfaces that interlock during insertion into the bar or corner socket. The plug and socket members snap together for a tight and straight fit that is released using a side release mechanism. The side release mechanism disengages the stretcher bar segments by pressing inward on the flat tooth surfaces of the latching arms of the connecting segments. The back side of the stretcher bar features a self-healing canvas fastening block for insertion of staples and other fasteners allowing the canvas to be stretched or removed.