Blockdiag

blockdiag and its family generate diagram images from simple text files:

Features

Supports many types of diagrams
- block diagram (w/ blockdiag)
- sequence diagram (w/ seqdiag)
- activity diagram (w/ actdiag)
- logical network diagram (w/ nwdiag)
Generates beautiful diagram images from simple text format (similar to graphviz’s DOT format)
Layouts diagram elements automatically
Embeds to many documentations; Sphinx, Trac, Redmine and some wikis