John O'Farrell

Advisory Partner (formerly General Partner) at Andreessen Horowitz

Reviewed Updated Mar 24, 2026

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a16z advisory partner who joined in 2010, investing $1M-$100M in enterprise, developer tools, and cloud infrastructure. Former EVP at Opsware and @Home; negotiated Opsware's $1.65B sale to HP and Silver Spring's $90M Series D.

Location Sunnyvale, California
Check Size $1M-$100M
Last Verified Investment PagerDuty (Series A) — Jan 2013
Social @JOHNOFA LinkedIn
Stage Focus
seed series-a growth
Sector Focus
enterprise developer-tools cloud-infrastructure cybersecurity ag-tech

Background

John O’Farrell is an Irish venture capitalist who joined Andreessen Horowitz in June 2010 as the firm’s third general partner and first non-founding partner 12. In July 2013, he transitioned from investing to an advisory role, becoming an Advisory Partner 3.

Before joining a16z, O’Farrell held executive vice president positions at three Silicon Valley technology companies 4. From 2001 to 2007, he was EVP of Business Development at Opsware (formerly Loudcloud), where he worked alongside CEO Ben Horowitz 1. Together they negotiated Loudcloud’s 2002 exit from the services business and its emergence as server automation software company Opsware, including a $52 million initial contract from EDS 1. O’Farrell led the expansion of Opsware’s product line through four acquisitions and orchestrated the sale of Opsware to Hewlett-Packard for $1.65 billion in June 2007 1.

From 1997 to 2001, O’Farrell was SVP of International at @Home Network (later Excite@Home), where he led the launch of broadband Internet services through joint ventures in the Benelux countries, Australia, and Japan 1. He joined Silver Spring Networks in January 2008 as EVP of Business Development, where he led the company’s $90 million Series D fundraising led by Kleiner Perkins and Google 1.

Earlier in his career, O’Farrell worked at Siemens and Digital Equipment in Germany and Luxembourg, at the European Commission, at Booz Allen Hamilton, at Eircom (formerly Telecom Eireann), and at US West 25. He holds a Bachelor of Electronic Engineering from University College Dublin and an MBA from Stanford Graduate School of Business, where he graduated as an Arjay Miller Scholar 14. He speaks English, French, German, and Portuguese 4.

Stated Thesis

O’Farrell has publicly described his investment focus as centered on technology founders building companies that can scale globally. In an interview with Silicon Republic, he stated: “Rather than being focused on mobile or social or local, we are much more focused on finding great companies” 5. He has emphasized the a16z model of supporting technology founders: “The entrepreneurs we invest in are technologists. We like technology founders, we bet that we can help them become great CEOs” 2.

O’Farrell has described a16z’s approach as delivering value beyond capital: “Capital is undifferentiated” and “The model we put together over the years is designed to deliver much more value than just capital” 2. He articulated the firm’s founding philosophy: “When Ben and Marc set out to found the firm, they realised that venture capital is really a cartel. So we set out to build a firm that would be extremely attractive to entrepreneurs” 2.

On investment decision-making, O’Farrell has stated: “The best investments are often controversial, and vigorous debate leads to better investment decisions” 6.

Inferred Thesis

Based on 10 verified investments where O’Farrell served as lead partner or board member, his actual investment behavior reveals the following patterns:

Sector distribution: O’Farrell’s portfolio spans enterprise software and infrastructure (PagerDuty, Slack, GoodData, IFTTT — 4 of 10, 40%), agriculture technology (Solum, Granular — 2 of 10, 20%), consumer internet/social (Facebook, Twitter, Groupon — 3 of 10, 30%), and mobile/telecom (ItsOn — 1 of 10, 10%). The enterprise and infrastructure concentration is notable, with 4 of the 7 companies where he took board seats being enterprise-focused 14.

Stage distribution: O’Farrell’s investments ranged from Series A (PagerDuty, IFTTT, Factual) to late-stage/secondary (Facebook, Twitter, Groupon). Based on available data: 4 of 10 (40%) were early-stage (Series A/B), 3 of 10 (30%) were growth/late-stage, and 3 of 10 (30%) were secondary market purchases. Sample size is small; these percentages should be treated as directional.

Operational value-add: O’Farrell’s distinctive contribution was in international expansion, M&A, and strategic partnerships, reflecting his operational background at Opsware and @Home Network. He served as board member on most of his investments 14.

Notable gap: Despite the stated focus on “finding great companies” rather than sectors, his portfolio shows a clear clustering in enterprise/B2B tools and agtech, with the consumer internet positions (Facebook, Twitter, Groupon) being secondary market purchases rather than direct seed/Series A investments.

Co-investor patterns: Accel appears alongside a16z in multiple O’Farrell investments (Slack, Factual). Khosla Ventures co-invested in both agtech companies (Solum, Granular).

Note: This analysis is based on only 10 verified investments. O’Farrell transitioned to an advisory role in 2013 after approximately three years of active investing, limiting the portfolio sample size.

Portfolio

Company Year Stage Source
Facebook 2010 Secondary 7
Tiny Speck/Slack 2010 Series A 89
Factual 2010 Series A 10
Twitter 2011 Secondary 11
Tiny Speck/Slack 2011 Series B 9
Groupon 2011 Series D 12
GoodData 2011 Series B 13
Solum 2012 Series B 1415
ItsOn 2012 Series B 16
IFTTT 2012 Series A 17
PagerDuty 2013 Series A 18

This table represents O’Farrell’s investments during his active investing period (2010-2013). He continued to advise portfolio companies after transitioning to Advisory Partner in July 2013.

In Their Own Words

“When Ben and Marc set out to found the firm, they realised that venture capital is really a cartel. So we set out to build a firm that would be extremely attractive to entrepreneurs.” — John O’Farrell, Irish Times interview, July 2016 2

“The entrepreneurs we invest in are technologists. We like technology founders, we bet that we can help them become great CEOs.” — John O’Farrell, Irish Times interview, July 2016 2

“Capital is undifferentiated.” — John O’Farrell, Irish Times interview, July 2016 2

“The best investments are often controversial, and vigorous debate leads to better investment decisions.” — John O’Farrell, AllThingsD, October 2012 6

“Hire people who are different from you, and who will have the courage to challenge you when it matters.” — John O’Farrell, AllThingsD, October 2012 6

“Today’s IT infrastructures have been heavily instrumented for incident detection, and while numerous sophisticated technologies exist to monitor for critical issues that could lead to downtime, little improvement has been made in how IT incidents are actually managed and resolved. PagerDuty is solving a critical problem that IT operations teams face and has the potential to significantly disrupt the multi-billion dollar IT Service Management market.” — John O’Farrell, PagerDuty Series A announcement, January 2013 18

“Stewart and team have proved our conservatism wrong — and how! They have built a fast-growing business that successfully serves customers ranging from the most disruptive and innovative startups to the largest and most demanding enterprises.” — John O’Farrell, a16z Slack announcement, 2019 9

“I have met some interesting companies. I would say Ireland has potential. It is really important, particularly for a small market like Ireland, to focus on gigantic markets up front and that usually means the US.” — John O’Farrell, Silicon Republic interview 5

“I don’t want to be a venture investor any longer, so I am shifting away from that.” — John O’Farrell on his 2013 role transition, AllThingsD, July 2013 3

What Founders Say

No independently sourced founder testimonials found. O’Farrell served on the boards of Slack, PagerDuty, Granular, GoodData, Factual, IFTTT, and ItsOn, but no direct founder quotes about his performance as an investor or board member were found through dedicated search.

Sources

  1. Wikipedia, “John O’Farrell (venture capitalist),” accessed March 2026. https://en.wikipedia.org/wiki/John_O%27Farrell_(venture_capitalist) ↩↩↩↩↩↩↩↩↩

  2. Irish Times, “Dubliner John O’Farrell is turning things around in Silicon Valley,” July 2016, accessed March 2026. https://www.irishtimes.com/business/technology/dubliner-john-o-farrell-is-turning-things-around-in-silicon-valley-1.27124↩↩↩↩↩↩↩↩

  3. AllThingsD, “Andreessen Horowitz’s First GP — John O’Farrell — Moves Out of Investing and Into Advisory Role,” July 2013, accessed March 2026. https://allthingsd.com/20130730/andreessen-horowitzs-first-gp-john-ofarrell-moves-out-of-investing-and-into-advisory-role↩↩

  4. Stanford IRISS, “John O’Farrell,” accessed March 2026. https://iriss.stanford.edu/people/john-ofarrell↩↩↩↩↩

  5. Silicon Republic, “A venture capitalist’s view of Ireland and Silicon Valley,” accessed March 2026. https://www.siliconrepublic.com/start-ups/a-venture-capitalists-view-of-ireland-and-silicon-valley↩↩↩

  6. AllThingsD, “Andreessen Horowitz Partner O’Farrell Discusses Hiring Different,” October 2012, accessed March 2026. https://allthingsd.com/20121022/hire-different/↩↩↩

  7. Wikipedia, “Andreessen Horowitz,” accessed March 2026. https://en.wikipedia.org/wiki/Andreessen_Horowitz↩

  8. Vator, “When Slack was young: the early years,” accessed March 2026. https://vator.tv/news/2018-04-03-when-slack-was-young-the-early-years↩

  9. Andreessen Horowitz, “Slack,” accessed March 2026. https://a16z.com/announcement/slack/↩↩↩

  10. VentureBeat, “Andreessen Horowitz writes big check for Factual’s data platform,” accessed March 2026. https://venturebeat.com/mobile/factual-funding-andreessen-horowitz/↩

  11. The Next Web, “Andreessen Horowitz invests $80 Million in Twitter,” February 2011, accessed March 2026. https://thenextweb.com/twitter/2011/02/09/andreessen-horowitz-invests-80-million-in-twitter/↩

  12. Vator, “Groupon closes monstrous $950M round,” January 2011, accessed March 2026. https://vator.tv/news/2011-01-10-groupon-closes-monstrous-950m-round↩

  13. AllThingsD, “GoodData Lands $15 Million in Funding From Andreessen Horowitz,” August 2011, accessed March 2026. https://allthingsd.com/20110818/gooddata-lands-15-million-in-funding-from-andreessen-horowitz/↩

  14. TechCrunch, “Software Is Feeding The World: Agriculture Startup Solum Raises $17M Led by Andreessen Horowitz,” June 2012, accessed March 2026. https://techcrunch.com/2012/06/27/software-is-feeding-the-world-agriculture-startup-solum-raises-17m-led-by-andreessen-horowitz/↩

  15. Andreessen Horowitz, “Software Is Eating the World—And Will Help to Feed It,” accessed March 2026. https://a16z.com/software-is-eating-the-world-and-will-help-to-feed-it/↩

  16. Business Wire, “ItsOn Inc Secures $15.5M in Series B Funding From Andreessen Horowitz,” October 2012, accessed March 2026. https://www.businesswire.com/news/home/20121030005483/en/ItsOn-Inc-Secures-15.5M-in-Series-B-Funding-From-Andreessen-Horowitz↩

  17. Andreessen Horowitz, “Put the Internet To Work For You,” December 2012, accessed March 2026. https://a16z.com/put-the-internet-to-work-for-you/↩

  18. Yahoo Finance, “PagerDuty Raises $10.7 Million Series A Funding Round Led by Andreessen Horowitz,” January 2013, accessed March 2026. https://finance.yahoo.com/news/pagerduty-raises-10-7-million-120000048.html↩↩

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