Behind the Site

Slack

slack.com

Business messaging and collaboration platform, now a Salesforce subsidiary, that began life as a video game studio's internal chat tool.

  • Enterprise software
  • acquired
  • Founded 2009
  • Researched Sep 2026
Confirmed
Age17 yearsDomain registered 1992
Confirmed
Based inSan Francisco, CaliforniaAlso New York City, US, Vancouver, Canada, London, UK, Tokyo, Japan, Dublin, Ireland, Pune, India, Melbourne, Australia
Likely
Employees1,000-5,000LinkedIn company page size band (2025-2026); Wikipedia reported 2,545 employees as of January 2021 pre-acquisition
Confirmed
Funding$841M raisedAngel $1.5M · Series A $5.0M · Series B $11M · Seed (Slack relaunch) $17M · Series C $43M · Series D $120M · Series E $160M · Series E (extension) $160M · Series F $200M · Series G $250M
Confirmed
PlatformsWeb, iPhone, Android, Mac, Windows, Linux, API
Confirmed
Founders4 foundersStewart Butterfield, Cal Henderson, Eric Costello, Serguei Mourachov

The story

Slack was created by Stewart Butterfield and co-founders as an internal tool at their gaming startup Tiny Speck, then spun out as a standalone chat product after the game Glitch failed. It grew through repeated VC rounds into a 2019 direct listing on the NYSE, before Salesforce acquired it for $27.7 billion in 2021. It now operates as a Salesforce-owned product line with several CEO changes since the acquisition.

Pivot · 2013

Browser-based MMORPG video game (Glitch) for consumers

Business team-messaging and collaboration software (Slack) for workplaces

Timeline

  1. Founded2009

    Tiny Speck founded

    Stewart Butterfield and co-founders start gaming studio in Vancouver

  2. Launch2011

    Glitch game launches

    Tiny Speck's MMORPG Glitch goes live, later shut down

  3. Pivot2013

    Slack app launches

    Internal chat tool becomes standalone product after Glitch closed

  4. RenamedAug 2014

    Company renamed Slack Technologies

    Tiny Speck renamed to match its new flagship product

  5. MilestoneJun 2019

    Direct listing on NYSE

    Slack goes public via direct listing, ticker WORK

  6. AcquiredJul 2021

    Salesforce completes acquisition

    Salesforce closes $27.7 billion purchase of Slack

  7. MilestoneDec 2022

    Founder CEO departs

    Stewart Butterfield leaves Salesforce/Slack leadership

  8. MilestoneDec 2025

    Interim CEO named

    Rob Seaman named interim CEO of Slack

Founders

  • Stewart Butterfield

    Founder (departed company Dec 2022)

    Co-founded Flickr; led Tiny Speck and was Slack's founding CEO until 2022

  • Cal Henderson

    Co-founder

    Co-founder of Tiny Speck/Slack, previously an engineer at Flickr

  • Eric Costello

    Co-founder

    Co-founder of Tiny Speck/Slack

  • Serguei Mourachov

    Co-founder

    Co-founder of Tiny Speck/Slack

8 sourcesEvery fact above links back to these.
  1. Slack Technologies - Wikipediaen.wikipedia.org
  2. Salesforce's Closed $27.7 Billion Slack Acquisitiondotsquares.com
  3. Stewart Butterfield, Slack CEO And Cofounder, Is Stepping Downforbes.com
  4. Slack Technologies, Inc. - Form 10-Q - FY2019sec.gov
  5. Slack | LinkedInlinkedin.com
  6. Slack | AI Work Platform & Productivity Tools (homepage evidence)slack.com
  7. RDAP registry record for slack.com (evidence)slack.com
  8. Slack app - App Store listing (evidence)apps.apple.com
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