Slack is hands down the best way to communicate quickly in teams or 1:1. If you need to organize discussions by topic (i.e. channels) and have everything in one place so it’s easy to find, then Slack is for you. Slack comes with a mobile app and integrates with many other apps you may already be using. Two new features were also recently introduced. Voice and video calling are now available for premium users.

Slack offers a freemium model, but the free tier will probably grant all your wishes.

Key Features

• Organize conversations by channels that can be divided up by team, project, client, etc.
• Talk it out over voice or video calls directly from Slack; you can also share your screen
• Integrated file sharing
• Bring important information and alerts into by connecting services like Zendesk, Salesforce, JIRA, and more with Slack — including your own proprietary software.
• For small team, the free version will probably meet your needs, but you can also choose between the Standard plan (€6.25/mo billed annually) or the Plus plan (€11.75/mo billed annually)

Check out this introduction video to see how it works: