Platforma might be a bit more popular than Flow. We know about 1 link to it since March 2021 and only 1 link to Flow. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
We use getflow.com for internal task management and email + meetings with clients. Tried tons of client facing tools and it never works. Source: about 3 years ago
There are some decent starters in the community (including some really great OS-native resources), but another option is purchase something like Platforma if you're looking to make interactive wireframes - https://platforma.ws/. Source: about 2 years ago
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
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.
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Basecamp - A simple and elegant project management system.
Method Wireframe Kit - Find your method of being incredibly fast in prototyping.