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.
Product Market Fit Toolkit - Measure your product-market fit using data you already have
Slack - A messaging app for teams who see through the Earth!
UserGuiding - User onboarding made easy, for less. Create product walkthroughs in a couple of clicks, without breaking the bank.
GrowthList - A crowd-sourced list of growth hacks
LEADx - Coaching for next-gen leaders