Startups (and other organisations) frequently work with a number of different people, and in many different places e.g. home offices, hot desk facilities, trains, cafes etc. Communication tools can really help this 'flexible' working approach.
By combining a few different tools, it is possible to cover more or less every area of your companies communication free of charge. Apps like Slack allow instant messaging along with the ability to exchange files. It's possible to make individual chat rooms for different projects/tasks allowing you to view a timeline of progress simply by scrolling up. Google drive is another great tool. Not only can you upload files, you can also use the various google versions of word / excel / powerpoint which can be reverted to a previous version at any time.
The article below provides short summaries of Slack, Google Drive, Zoom, Trello and Invision. What's your favourite communication tool?