productboard - Beautiful and powerful product management.
Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
FastNetMon - FastNetMon is a very fast DDoS analyzer with sflow/netflow/mirror support.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
ProdPad - ProdPad helps your team gather ideas, surface the best ones and turn them into product specs, and then put it all on a product roadmap.
Redmine - Flexible project management web application