Microsoft vs Slack: Founders, CEOs and History
Microsoft was founded in 1975 by Bill Gates, Paul Allen and is led by Satya Nadella. Slack was founded in 2009 by Stewart Butterfield, Cal Henderson, Eric Costello and is led by Rob Seaman (EVP & General Manager).
Company facts
Founders
Microsoft
Bill Gates
Microsoft possesses arguably the most well-known, foundational founding story of the entire personal computing revolution, rooted in the intense, effective partnership of two teenage computer prodigies who recognized the software potential of the microcomputer…
Paul Allen
Paul Allen co-founded Microsoft and was crucial to its earliest technical and strategic decisions. He helped develop Altair BASIC, gave the company its original name, and participated in the operating-system opportunity that led to MS-DOS.
Slack
Stewart Butterfield
Stewart Butterfield co-founded Tiny Speck in 2009 and led its pivot from the game Glitch to Slack. He was Slack's CEO through its 2019 direct listing and the 2021 Salesforce acquisition, and stepped down after announcing his departure in December 2022.
Cal Henderson
Cal Henderson co-founded Tiny Speck and served as Slack's chief technology officer, overseeing the backend and developer platform as usage grew after the 2014 launch.
Eric Costello
Eric Costello co-founded Tiny Speck and worked on Slack's early product and front-end engineering.
Serguei Mourachov
Serguei Mourachov co-founded Tiny Speck and worked on server-side engineering for Glitch and early Slack.
CEOs and their tenures
Microsoft
- Bill Gates1975–2000
Co-founder and CEO
Gates built Microsoft's licensing model: software sold to many hardware makers rather than tied to one.
Source - Steve Ballmer2000–2014
CEO
Ballmer grew revenue from about $23 billion in FY2000 to about $78 billion in FY2013 and built the enterprise server and sales business that Azure later scaled on.
Source - Satya Nadella2014–present
Chairman and CEO
Nadella made Azure and Microsoft 365 the company's core, opened Microsoft to Linux and open source, and positioned it early in generative AI through OpenAI.
Source
Slack
- Stewart Butterfield2009–2022
Co-Founder & Former CEO
Led Tiny Speck's pivot to Slack, the 2019 NYSE direct listing and the 2021 sale to Salesforce; announced his departure in December 2022.
Source - Denise Dresser2023–2025
Chief Executive Officer
Longtime Salesforce executive who ran Slack from December 2023, oversaw Slack AI and Agentforce integration, and left in December 2025 to become OpenAI's chief revenue officer.
Source - Lidiane Jones2023–2023
Chief Executive Officer
Former Salesforce EVP who led Slack for most of 2023, including the initial Slack AI and Canvas rollout, before becoming CEO of Bumble.
Source - Rob Seaman2025–present
EVP & General Manager, Slack
Slack chief product officer who took over Denise Dresser's duties on an interim basis in December 2025 and was named EVP & GM of Slack in February 2026; led the Slackbot launch and the March 2026 AI feature release.
Source
Timeline: Microsoft and Slack side by side
1975Microsoft
Microsoft Founded
Bill Gates and Paul Allen founded Microsoft after recognizing that the Altair 8800 needed usable programming software. Their first product, Altair BASIC, turned a hobbyist computer kit into a programmable platform.
1981Microsoft
MS-DOS Ships With IBM PC
IBM introduced its personal computer with MS-DOS 1.0 and other Microsoft products. The milestone mattered because Microsoft's operating-system work moved from a small software supplier's project into the emerging corporate PC standard.
1985Microsoft
Windows Launch
The release of Windows 1.0 began Microsoft's long move from command-line operating systems to graphical personal computing. The first version was not an instant blockbuster, but it gave Microsoft a user-interface path that could evolve with PC hardware.
1990Microsoft
Office Suite Release
The bundling of Word, Excel, and PowerPoint into Microsoft Office created a productivity suite that became central to business work. The bundle simplified enterprise purchasing and made file compatibility a competitive weapon.
1998Microsoft
U.S. Antitrust Case
The U.S. Department of Justice accused Microsoft of using Windows power to suppress browser competition. The case mattered because it placed Microsoft's platform tactics under public and legal scrutiny at the height of its PC strong position.
2009Slack
Tiny Speck Founded in San Francisco
Stewart Butterfield and co-founders established Tiny Speck to build multiplayer game Glitch.
2010Microsoft
Azure Commercial Launch
Azure gave Microsoft a way to compete in cloud infrastructure as enterprise customers began shifting workloads away from company-owned servers.
2012Slack
Glitch Closes & Internal Chat Pivots to Slack
Glitch ceased operations, prompting the team to commercialize their internal communication utility.
2013Slack
Private Beta Launch Earns 8,000 Signups in 24 Hours
Released private beta preview, igniting viral word-of-mouth adoption across Silicon Valley tech startups.
2014Microsoft
Satya Nadella CEO
Satya Nadella became CEO and moved Microsoft away from a strategy that forced every product to serve Windows. He prioritized Azure, Microsoft 365, open source, Linux support, cross-platform software, and a more collaborative developer posture.
2014Slack
Official Public Launch & Fast-Track Unicorn Status
Launched publicly, reaching a $1.1B valuation in eight months as the fastest-growing enterprise app in history.
2016Microsoft
LinkedIn Acquisition
Microsoft agreed to acquire LinkedIn in 2016 for $26.2 billion in cash. The deal mattered because it added a professional identity network to a company already strong in Office, Dynamics, cloud services, recruiting tools, advertising, and enterprise sales.
2017Slack
Launch of Slack Enterprise Grid for Fortune 500
Introduced Enterprise Grid, unlocking large-scale deployments for IBM, Target, and Capital One.
2018Microsoft
GitHub Acquisition
Microsoft acquired GitHub for $7.5 billion in stock, reversing years of developer skepticism toward the company. The acquisition placed Microsoft inside the daily workflow of software developers across languages, clouds, and operating systems.
2019Slack
NYSE Direct Listing (WORK)
Listed directly on the New York Stock Exchange on June 20, 2019.
2020Slack
Salesforce Announces $27.7B Acquisition Agreement
Marc Benioff announced Salesforce's landmark $27.7 billion acquisition of Slack to create Customer 360's digital HQ.
2021Slack
Acquisition Closes & Integration with Salesforce Begins
Salesforce completed the acquisition on July 21, 2021.
2023Microsoft
AI Leadership
Microsoft's expanded OpenAI partnership and Copilot product rollout placed the company at the center of enterprise generative AI adoption.
2023Microsoft
Activision Blizzard Acquisition Closes
Microsoft completed the Activision Blizzard acquisition after intense regulatory review. The deal added Call of Duty, World of Warcraft, Diablo, Overwatch, Candy Crush, and other franchises to Microsoft Gaming.
2023Slack
Denise Dresser Appointed CEO & Launch of Slack AI
Denise Dresser succeeded Lidiane Jones in December 2023 as Slack AI and Canvas rolled out.
2025Slack
Dresser Departs; AI Bundled Into Plans
Slack folded AI features into paid plans in 2025, and Denise Dresser left for OpenAI in December.
2026Slack
Slackbot Becomes a Personal AI Agent
Slackbot reached general availability in January 2026, followed by 30 AI features announced in March.
Acquisitions
Microsoft
- Activision Blizzard2023$68.7B
- Nuance Communications2022$19.7B
- ZeniMax Media2021$7.5B
- GitHub2018$7.5B
- LinkedIn2016$26.2B
Slack
- Rimeto2020Undisclosed
- Astro Technology2018Undisclosed
- Missions (from Robot & Pencil)2018Undisclosed
- Screenhero2015Undisclosed
Questions about Microsoft vs Slack
Who is the CEO of Microsoft Corporation and Slack Technologies, LLC?
Microsoft Corporation is led by Satya Nadella and Slack Technologies, LLC is led by Rob Seaman (EVP & General Manager). Both serve as the top executive responsible for the company's strategy, operations, and financial performance.
When was Microsoft Corporation founded vs Slack Technologies, LLC?
Microsoft Corporation was founded in 1975 — 34 years before Slack Technologies, LLC, which was founded in 2009. Microsoft Corporation's longer operating history gives it a deeper track record but also potentially more institutional inertia compared to the younger Slack Technologies, LLC.
How many employees does Microsoft Corporation have compared to Slack Technologies, LLC?
Microsoft Corporation employs approximately 223,000 people. A verified employee count for Slack Technologies, LLC is not currently available.
Where are Microsoft Corporation and Slack Technologies, LLC headquartered?
Both Microsoft Corporation and Slack Technologies, LLC are headquartered in United States, meaning they operate under the same primary regulatory and tax environment.
Who founded Microsoft Corporation and Slack Technologies, LLC?
Microsoft Corporation was founded by Bill Gates, Paul Allen. Slack Technologies, LLC was founded by Stewart Butterfield, Cal Henderson, Eric Costello, Serguei Mourachov.
Which company has a longer operating history — Microsoft Corporation or Slack Technologies, LLC?
Microsoft Corporation has been operating for approximately 51 years, making it the more established of the two companies. Slack Technologies, LLC has been in operation for around 17 years. A longer operating history often signals greater institutional resilience and brand recognition, though it can also mean slower adaptation to new market conditions.
Figures come from each company's filings and the sources linked beside them. Amounts reported in another currency are shown in US dollars at an approximate rate and marked with ~. Back to the Microsoft vs Slack overview