# Slack funding: rounds and investors > Slack has raised $1.2B across 10 rounds since 2009. Investors include Accel, Andreessen Horowitz and Social Capital. Every round with its source. Source: https://millionrounds.com/company/slack (Millionrounds; every figure on the page links to its filing or article) United States · [Series H startup](https://millionrounds.com/companies) # Who invested in *Slack* 10 rounds we have observed, with the 26 investors named in them. Every figure came from a named source, and where the company reported a raise to the SEC itself, that is shown beside it. Collaboration Tools SaaS Telecoms Funding summary Updated 26 Oct 2026 **$1.2B** raised across 10 rounds since 2009, from 10 sources **$1.5M** Seed **$5.0M** Series A **$11M** Series B **$43M** Series C **$120M** Series D **$160M** Series E **$200M** Growth **$250M** Round **$427M** Series H - **Latest round:** Series H, $427M Aug 2018 - **Step-up i:** 1.7× - **Investors:** 26 (1 led) See who backed them ## The funding story Each circle is a round, placed by date and sized by amount. The line above is the running total. 2009 2011 2013 2015 2017 **$1.5M** Seed **?** Seed **$5.0M** Series A **$11M** Series B **$43M** Series C **$120M** Series D **$160M** Series E **$200M** Growth **$250M** Round **$427M** Series H - **First round:** Seed, $1.5M - **Biggest round:** $427M - **Usual gap between rounds:** 12 months ## The rounds - **Aug 2018** Series H **$427M** *3 new* [General Atlantic](https://millionrounds.com/fund/general-atlantic) [Baillie Gifford](https://millionrounds.com/fund/baillie-gifford) [SANDS](https://millionrounds.com/fund/sands) Reported by FinSMEs - **Sept 2017** Round **$250M** *1 new* [SoftBank's Vision Fund](https://millionrounds.com/fund/softbank-s-vision-fund) Reported by Qz - **Apr 2016** Growth **$200M** *4 new* *3 returning* [Thrive Capital](https://millionrounds.com/fund/thrive-capital-2) Lead [Accel](https://millionrounds.com/fund/accel) [Index Ventures](https://millionrounds.com/fund/index-ventures) [Social Capital](https://millionrounds.com/fund/social-capital) [Comcast Ventures](https://millionrounds.com/fund/comcast-ventures) [GGV](https://millionrounds.com/fund/ggv) [Spark Growth](https://millionrounds.com/fund/spark-growth) Reported by BetaKit: funding - **Apr 2015** Series E **$160M** *6 new* *5 returning* [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) [Accel](https://millionrounds.com/fund/accel) [Index Ventures](https://millionrounds.com/fund/index-ventures) [Google Ventures](https://millionrounds.com/fund/gv) [Kleiner Perkins Caufield & Byers](https://millionrounds.com/fund/kleiner-perkins-caufield-and-byers) [Spark Capital](https://millionrounds.com/fund/spark-capital) [IVP](https://millionrounds.com/fund/ivp) [Social Capital](https://millionrounds.com/fund/social-capital) [Horizons Ventures](https://millionrounds.com/fund/horizons-ventures) [DST Global](https://millionrounds.com/fund/dst-global) [Groupe Arnault](https://millionrounds.com/fund/groupe-arnault) From a historical funding record - **Oct 2014** Series D **$120M** *3 new* *4 returning* [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) [Accel](https://millionrounds.com/fund/accel) [Google Ventures](https://millionrounds.com/fund/gv) [Kleiner Perkins Caufield & Byers](https://millionrounds.com/fund/kleiner-perkins-caufield-and-byers) [Slow Ventures](https://millionrounds.com/fund/slow-ventures) [Social Capital](https://millionrounds.com/fund/social-capital) [The Social+Capital Partnership](https://millionrounds.com/fund/the-social-capital-partnership) From a historical funding record - **Apr 2014** Series C **$43M** *2 new* *2 returning* [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) [Accel](https://millionrounds.com/fund/accel) [Social Capital](https://millionrounds.com/fund/social-capital) [The Social+Capital Partnership](https://millionrounds.com/fund/the-social-capital-partnership) From a historical funding record - **Apr 2011** Series B **$11M** *2 returning* [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) [Accel](https://millionrounds.com/fund/accel) Reported by techcrunch.com - **Apr 2010** Series A **$5.0M** *1 new* *1 returning* [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) [Accel](https://millionrounds.com/fund/accel) Reported by gigaom.com - **Mar 2010** Seed **Amount undisclosed** *1 new* [SV Angel](https://millionrounds.com/fund/sv-angel) From a historical funding record - **Jan 2009** Seed **$1.5M** *5 new* [Accel](https://millionrounds.com/fund/accel) [Marc Andreessen](https://millionrounds.com/fund/marc-andreessen) [Jeff Weiner](https://millionrounds.com/fund/jeff-weiner) [Bradley Horowitz](https://millionrounds.com/fund/bradley-horowitz) [Rob Solomon](https://millionrounds.com/fund/rob-solomon) Reported by news.cnet.com ## Who was in which round The busiest backers across the latest rounds. A filled square is a round they joined; a dark one, a round they led. **Series A** 2010 **Series B** 2011 **Series C** 2014 **Series D** 2014 **Series E** 2015 **Growth** 2016 **Round** 2017 **Series H** 2018 [Accel](https://millionrounds.com/fund/accel) [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) [Social Capital](https://millionrounds.com/fund/social-capital) [Index Ventures](https://millionrounds.com/fund/index-ventures) [Google Ventures](https://millionrounds.com/fund/gv) [Kleiner Perkins Caufield & Byers](https://millionrounds.com/fund/kleiner-perkins-caufield-and-byers) [The Social+Capital Partnership](https://millionrounds.com/fund/the-social-capital-partnership) [Thrive Capital](https://millionrounds.com/fund/thrive-capital-2) L [SV Angel](https://millionrounds.com/fund/sv-angel) [Spark Capital](https://millionrounds.com/fund/spark-capital) ## Everyone who backed them [Accel](https://millionrounds.com/fund/accel) VC firm **7** rounds [Andreessen Horowitz](https://millionrounds.com/fund/andreessen-horowitz) VC firm **5** rounds [Social Capital](https://millionrounds.com/fund/social-capital) VC firm **4** rounds [Index Ventures](https://millionrounds.com/fund/index-ventures) VC firm **2** rounds [Google Ventures](https://millionrounds.com/fund/gv) Corporate VC **2** rounds [Kleiner Perkins Caufield & Byers](https://millionrounds.com/fund/kleiner-perkins-caufield-and-byers) VC firm **2** rounds [The Social+Capital Partnership](https://millionrounds.com/fund/the-social-capital-partnership) VC firm **2** rounds [Thrive Capital](https://millionrounds.com/fund/thrive-capital-2) Family office **1** round, led 1 [SV Angel](https://millionrounds.com/fund/sv-angel) VC firm **1** round [Spark Capital](https://millionrounds.com/fund/spark-capital) VC firm **1** round [Slow Ventures](https://millionrounds.com/fund/slow-ventures) VC firm **1** round [IVP](https://millionrounds.com/fund/ivp) VC firm **1** round [General Atlantic](https://millionrounds.com/fund/general-atlantic) Private equity **1** round [Comcast Ventures](https://millionrounds.com/fund/comcast-ventures) Corporate VC **1** round [Horizons Ventures](https://millionrounds.com/fund/horizons-ventures) VC firm **1** round [DST Global](https://millionrounds.com/fund/dst-global) Private equity **1** round [Baillie Gifford](https://millionrounds.com/fund/baillie-gifford) Asset manager **1** round [Marc Andreessen](https://millionrounds.com/fund/marc-andreessen) Angel **1** round [Groupe Arnault](https://millionrounds.com/fund/groupe-arnault) Family office **1** round [Jeff Weiner](https://millionrounds.com/fund/jeff-weiner) VC firm **1** round [SANDS](https://millionrounds.com/fund/sands) VC firm **1** round [Bradley Horowitz](https://millionrounds.com/fund/bradley-horowitz) VC firm **1** round [Rob Solomon](https://millionrounds.com/fund/rob-solomon) VC firm **1** round [SoftBank's Vision Fund](https://millionrounds.com/fund/softbank-s-vision-fund) Investment firm **1** round [GGV](https://millionrounds.com/fund/ggv) Growth equity **1** round [Spark Growth](https://millionrounds.com/fund/spark-growth) Growth equity **1** round Missing a round, or an investor who was in one? [Tell us](https://millionrounds.com/corrections?slug=slack). ## Also claim to have backed them These 20 firms list Slack as a portfolio company on their own websites, but no report of a round names them. They are the firms' own claims, kept apart from the rounds above. [Notable Capital](https://millionrounds.com/fund/notable-capital) VC firm Per its own site [S32](https://millionrounds.com/fund/s32) VC firm Per its own site [Glynn Capital Management](https://millionrounds.com/fund/glynn-capital) VC firm Per its own site [Section 32](https://millionrounds.com/fund/section-32) VC firm Per its own site [Slack](https://millionrounds.com/fund/slack) Corporate VC Per its own site [Light Street Capital](https://millionrounds.com/fund/light-street-capital) VC firm Per its own site [Jayesh Parekh](https://millionrounds.com/fund/jayesh-parekh) Angel Per its own site [Todd Dagres](https://millionrounds.com/fund/todd-dagres) VC firm Per its own site [Canine Capital](https://millionrounds.com/fund/canine-capital) Private credit Per its own site [Conduit](https://millionrounds.com/fund/conduit) Accelerator Per its own site [Global Alternative Investment Management](https://millionrounds.com/fund/global-alternative-investment-management) VC firm Per its own site [Good Today](https://millionrounds.com/fund/good-today) Investment firm Per its own site [Nakuru Box Innovation Center](https://millionrounds.com/fund/nakuru-box-innovation-center) Incubator Per its own site [Next Play Ventures](https://millionrounds.com/fund/next-play-ventures) VC firm Per its own site [Next Round Capital Partners](https://millionrounds.com/fund/next-round-capital-partners) VC firm Per its own site [Rsquared Communication](https://millionrounds.com/fund/rsquared-communication) VC firm Per its own site [SPORTS TECH TOKYO](https://millionrounds.com/fund/sports-tech-tokyo) Accelerator Per its own site [Salesforce Foundation](https://millionrounds.com/fund/salesforce-foundation) Corporate VC Per its own site [TOP Venture SA](https://millionrounds.com/fund/top-venture-sa) Family office Per its own site [Unanimous Capital](https://millionrounds.com/fund/unanimous-capital) VC firm Per its own site ## Quick answers about Slack ### Who invested in Slack? Slack's investors include Accel, Andreessen Horowitz, Social Capital, Index Ventures and Google Ventures, and 21 more on record. ### How much has Slack raised? Slack has raised $1.2B across 10 rounds since 2009. One round did not disclose an amount, so the total is a floor. ### When did Slack last raise? Slack's most recent round was a Series H of $427M in Aug 2018. ### What was Slack's biggest round? Its most recent round, $427M in Aug 2018, is also its largest on record. ### Who backed Slack first? Slack's first round on record, in Jan 2009, was backed by Accel, Marc Andreessen and Jeff Weiner and 2 others. ### What stage is Slack at? Slack's latest named round is a Series H, in Aug 2018. ### Where is Slack based? Slack is based in the United States. ### Who led Slack's rounds? Thrive Capital led the Growth in 2016. ## Companies like Slack In the same sector, and raised in the last eighteen months. [**CapitalOS** $52M · Oct 2026](https://millionrounds.com/company/capitalos)[**DashFuel** Oct 2026](https://millionrounds.com/company/dashfuel)[**TruAgents** $3.4M · Oct 2026](https://millionrounds.com/company/truagents)[**Qualitate** $32M · Oct 2026](https://millionrounds.com/company/qualitate)[**DrizzleX** $9.1M · Oct 2026](https://millionrounds.com/company/drizzlex)[**Town** $241M · Oct 2026](https://millionrounds.com/company/town) ## Find investors like these Search every investor by what they have actually funded, then narrow to your stage and market. Free. Open the investor searchOr these rounds in the app