ETR survey of ~580 CIOs or IT decision makers at large enterprises reveals 59% use or plan to adopt Microsoft Teams compared with 35% for Slack
Microsoft Teams isn't better than Slack, but it is freer. — Tech workers' favorite communications tool, Slack, is losing ground to its biggest rival …
Context & Ripple Effects
Microsoft has been methodically converting its installed base into Teams users since it began replacing Skype for Business with Teams in 2017, reaching 200K organizations within a year of launch and posting rapid market-share gains in a survey of 900 IT companies across the US and Europe. The new ETR poll of ~580 large-enterprise CIOs is the cleanest read yet on where that lands inside big-company buying decisions: 59% use or plan to adopt Teams versus 35% for Slack.
First-order effects
- Slack's core enterprise motion — winning IT decision makers deal by deal on product merit — now runs against a rival that reaches most large enterprises at no incremental cost through the Office bundle, which is why Vox frames Teams as 'freer' rather than better.
- Slack retains a real stronghold elsewhere: Kruze Consulting found 60% of funded startups paid for Slack while only 12% paid for the Office bundle that includes Teams, so the ETR result sharpens a two-market split rather than ending the contest.
Second-order effects
- Slack faces mounting pressure to prove standalone value against free bundling — the same dynamic that preceded its 12% drop below Teams' claimed DAU lead when Microsoft reported 20M DAUs in November and Slack's stock fell 7%.
- Enterprise software rivals selling adjacent Office-competing suites now face the same bundling math, pushing them toward their own all-in-one pricing or partnerships to stay in CIO evaluations.
Third-order effects
- If bundling keeps deciding enterprise collaboration purchases, the category consolidates around suite owners — consistent with Stratechery's framing of Teams as part of Microsoft's 'OS for the cloud' versus Slack's attempt to build an enterprise network via Connect — leaving best-of-breed tools to compete on segments the bundles underserve.
The trend: Enterprise collaboration is consolidating around cloud-suite vendors whose products ship free inside broader bundles, squeezing standalone tools into niche or premium positions.