[jjmarr]

gcc comes to mind. Remember when every computer came with its own C compiler? LaTeX also killed proprietary mathematics typesetting.

[jhbadger]

GCC's gotten so popular that some operating systems like MacOS lie about it and make "gcc" an alias by default for their clang compiler!

[drewmcarthur]

this is what i’m thinking. HTTP itself only overtook Gopher when it was released into the public domain, to compete with Gopher’s proprietary licensing.