Microsoft Teams vs Slack: who uses which
Customers, public proof and the companies that use both.
On usedby, 5 companies use Microsoft Teams and 50 use Slack. 1 company uses both, including Read AI. Slack leads among the Artificial Intelligence companies on usedby that use either tool.Latest check Nov 13, 2026: 55 of 55 public lines checked. Counts include every proof level, job-post signals included. A company on both tools counts at any proof level, and a job post on one side is marked as such.
Who uses Microsoft Teams, Slack, or both
Every company with a public proof for at least one of the two tools.
4
listed for Microsoft Teams only
1
company uses both
49
listed for Slack only
On usedby, 4 companies are listed for Microsoft Teams only, 49 are listed for Slack only and 1 uses both, out of the 54 companies listed for at least one. An absent listing does not prove non-use.
Who uses both
Companies with a public line on both tools, at any proof level: the strongest proofs come first, and a job post is marked.
| Company | First public proof, Microsoft Teams | First public proof, Slack |
|---|---|---|
 Read AI | On or before Nov 2026 | On or before Nov 2026 |
Side by side
Facts from our data and from each vendor's public pages. Each line says where it comes from.
Vendor facts checked: Microsoft Teams, 0 of 6; Slack, 4 of 6. Missing facts remain unverified, not absent features.
Microsoft Teams
SlackWhat customers report
Results as the vendor or the customer published them, with the source and the date.
Microsoft Teams
No reviewed story for Microsoft Teams yet.
Slack
that would take someone more than an hour
Mural
Vendor case study, slack.com, captured Nov 12, 2026
saves me four to five hours each week
Isometric
Vendor case study, slack.com, captured Nov 12, 2026
Questions about Microsoft Teams and Slack
Which is used more, Microsoft Teams or Slack?
Slack has more customers on usedby: 50 against 5 for Microsoft Teams.
Do companies use both Microsoft Teams and Slack?
Yes. 1 company uses both on usedby, including Read AI.
Who uses Microsoft Teams?
5 companies on usedby, each with the public page that shows it. See who uses Microsoft Teams.
Who uses Slack?
50 companies on usedby, each with the public page that shows it. See who uses Slack.
How does usedby count customers?
A company counts when a public page shows it: a vendor's customer page, a case study, a press release or a job post, most saved with a dated capture. Every line is a customer, at one of four proof levels: confirmed, declared by the company itself, observed or signal (a job post, the weakest). A company counts as using both tools when it has a line on each, at any level; the list shows the strongest proofs first and marks job posts.