Swiss_system is a project mainly written in Ruby, it's free.
It's tool for play swiss system tournament
You have to install gem
Next you can start by "swiss" command in command line1. You have to add players
2. Click new game(In first game program random players paring)
3. Input results
4. Click next game(program paring players by points)
5. Input results
6. Repeat point 4 and 5 how many is rounds in tournament