Teams, Slack and Zoom get lumped together as 'the chat-and-video apps', and that is exactly why businesses end up paying for two or three of them at once. They overlap, but each was built to be best at one thing. Sort out what each is genuinely for and you can usually drop one, save money, and stop your staff bouncing between three tabs to have one conversation.
What each one was actually built to do
These three started life solving different problems, and they are still strongest at their original job.
- •Microsoft Teams: built as an all-in-one hub - chat, video, calls and file sharing, tightly woven into Microsoft 365. Strongest as the daily workspace if you already use Microsoft.
- •Slack: built as a chat-first tool for fast, organised team messaging, with a vast library of app integrations. Strongest where conversation and connecting other tools is the lifeblood.
- •Zoom: built as a video-meeting tool, and still the benchmark for large, reliable, easy-to-join calls - especially with people outside your company.
The big overlap, and why it confuses everyone
Here is the trap: all three now do a bit of everything. Teams and Slack both have video; Zoom has added chat; everyone has file sharing. On the surface they look interchangeable, which is precisely why firms over-buy.
But 'can do' is not 'is best at'. Zoom can chat, but few teams want to live in it all day. Teams can host webinars, but Zoom does big external calls more smoothly. The skill is matching the tool to where your team's centre of gravity actually sits, not to the longest feature list.
The cost and licensing reality
This is where real money is won or lost. If you already pay for Microsoft 365, you already have Teams at no extra cost - it is bundled into the plans we cover in our Microsoft 365 plans guide.
That single fact reshapes the decision. Many firms pay separately for Slack and Zoom while Teams sits unused in a subscription they already own. Sometimes that is justified - the other tools really are better for how they work. Often it is pure waste, two paid products duplicating one they have already bought. Before renewing anything, check what your 365 licences already include.
When each genuinely wins
Strip away the marketing and clear patterns emerge for which tool suits which business.
Teams wins when you are already a Microsoft 365 shop and want one integrated hub for internal work - it is the natural, no-extra-cost default. Slack wins when fast, threaded team chat and deep integration with lots of other apps is how your team operates, especially in tech and creative firms. Zoom wins when external, client-facing or large-scale video calls are central - sales, training, webinars - where its reliability and ease of joining stand out. Plenty of firms land on Teams for internal life plus Zoom for external meetings, and skip Slack entirely.
Choosing without overthinking it
Start from what you already pay for and what your work truly demands, not from the app with the most features.
If you have Microsoft 365, trial Teams properly before paying for anything else - it may cover the lot. If your team thrives on chat and integrations, Slack earns its keep. If your business runs on external video, keep Zoom regardless of the rest. And whichever you standardise on, lock down who can access it: these tools carry sensitive conversations and files, so good identity and access management and multi-factor authentication matter. For the wider suite decision behind all this, see Microsoft 365 vs Google Workspace.