I've compiled and added to this list over time. When you go digging for how old the founders of major tech companies have been, you'll find they're overwhelmingly closer to their mid 30s, nearly all are over ~27, with plenty in their 40s. Exceptionally few have been like Gates, Jobs and Zuckerberg. If you're 30 and you think it's too late, it's not, you may not have even hit your prime yet.

Ages of founders:

Paul Graham (31, Viaweb), Jan Koum (33, WhatsApp), Brian Acton (37, WhatsApp), Ev Williams (34, Twitter), Jack Dorsey (30, Twitter; 33, Square), Elon Musk (31, SpaceX; 32, Tesla), Garrett Camp (30, Uber), Travis Kalanick (32, Uber), Brian Chesky (27, Airbnb), Adam Neumann (31, WeWork), Reed Hastings (37, Netflix), Reid Hoffman (36, LinkedIn), Jack Ma (35, Alibaba), Jeff Bezos (30, Amazon), Jerry Sanders (33, AMD), Marc Benioff (35, Salesforce), Ross Perot (32, EDS), Peter Norton (39, Norton), Larry Ellison (33, Oracle), Mitch Kapor (32, Lotus), Leonard Bosack (32, Cisco), Sandy Lerner (29, Cisco), Gordon Moore (39, Intel), Mark Cuban (37, Broadcast.com), Scott Cook (31, Intuit), Nolan Bushnell (29, Atari), Paul Galvin (33, Motorola), Irwin Jacobs (52, Qualcomm), David Duffield (46, PeopleSoft; 64 Workday), Aneel Bhusri (39, Workday), Thomas Siebel (41, Siebel Systems), John McAfee (42, McAfee), Gary Hendrix (32, Symantec), Scott McNealy (28, Sun), Markus Persson (30, Mojang), Craig Newmark (43, Craigslist), James Goodnight (33, SAS), John Sall (28, SAS), Diane Greene (43, VMWare), Mendel Rosenblum (36, VMWare), Bill Coleman (48, BEA Systems), Evan Goldberg (35, NetSuite), David Sacks (36, Yammer), Jack Smith (28, Hotmail), Sabeer Bhatia (28, Hotmail), Chad Hurley (28, YouTube), Andy Rubin (37, Danger; 41, Android), Rodney Brooks (36, iRobot), Jeff Hawkins (35, Palm), Niklas Zennström (37, Skype), Janus Friis (27, Skype), David Bohnett (38, Geocities), Bill Gross (40, GoTo.com/Overture), Subrah Iyar (38, WebEx), Min Zhu (47, WebEx), Pierre Omidyar (28, eBay), Rich Barton (29 for Expedia, 38 for Zillow), Jim Clark (38 for SGI, and 49 for Netscape), Charles Wang (32, CA), David Packard (27, HP), John Warnock (42, Adobe), Robert Noyce (30 at Fairchild, 41 for Intel), Rod Canion (37, Compaq), Jen-Hsun Huang (30, nVidia), Eli Harari (41, SanDisk), Sanjay Mehrotra (28, SanDisk), Al Shugart (48, Seagate), Finis Conner (34, Seagate), Henry Samueli (37, Broadcom), Henry Nicholas (32, Broadcom), Charles Brewer (36, Mindspring), William Shockley (45, Shockley), Ron Rivest (35, RSA), Adi Shamir (30, RSA), John Walker (32, Autodesk), Halsey Minor (30, CNet), David Filo (28, Yahoo), Jeremy Stoppelman (27, Yelp), Eric Lefkofsky (39, Groupon), Andrew Mason (29, Groupon), Wilfred Corrigan (43, LSI), Joe Parkinson (33, Micron), Aart J. de Geus (32, Synopsys), John Moores (36, BMC Software), Vivek Ranadivé (40, Tibco), Michael Baum (41, Splunk), Suhas Patil (37, Cirrus Logic), T. J. Rodgers (34, Cypress Semi), Scott Scherr (37, Ultimate Software), Ray Stata (31, Analog Devices), Ross Freeman (36, Xilinx), David Hitz (28, NetApp), Brian Lee (28, Legalzoom), Demis Hassabis (34, DeepMind), Tim Westergren (35, Pandora), Martin Lorentzon (37, Spotify), Ashar Aziz (44, FireEye), Kevin O'Connor (36, DoubleClick), Ben Silbermann (28, Pinterest), Evan Sharp (28, Pinterest), Steve Kirsch (38, Infoseek), Stephen Kaufer (36, TripAdvisor), Michael McNeilly (28, Applied Materials), Eugene McDermott (52, Texas Instruments), Richard Egan (43, EMC), Gary Kildall (32, Digital Research), Hasso Plattner (28, SAP), Robert Glaser (32, Real Networks), Patrick Byrne (37, Overstock.com), Marc Lore (33, Diapers.com), Ed Iacobucci (36, Citrix Systems), Ray Noorda (55, Novell), Tom Leighton (42, Akamai), Daniel Lewin (28, Akamai), Michael Mauldin (35, Lycos), Tom Anderson (33, MySpace), Chris DeWolfe (37, MySpace), Mark Pincus (41, Zynga), Nir Zuk (30, Palo Alto Networks), Caterina Fake (34, Flickr), Stewart Butterfield (31 for Flickr; 40 for Slack), Kevin Systrom (27, Instagram), Adi Tatarko (37, Houzz), Brian Armstrong (29, Coinbase), Pradeep Sindhu (43, Juniper), Peter Thiel (31, PayPal; 37, Palantir), Jay Walker (42, priceline.com), Tom Gosner (40, DocuSign), Shay Banon (31, Elastic), Beerud Sheth (29, Elance), Arkady Volozh (36, Yandex), Hiroshi Mikitani (34, Rakuten), Morris Chang (56, Taiwan Semi)

It has also largely held true in China:

Pony Ma (27, Tencent), Robin Li (32, Baidu), Liu Qiangdong (29, JD.com), Lei Jun (40, Xiaomi), Ren Zhengfei (38, Huawei), Cheng Wei (29, Didi Chuxing), James Liang (29, Ctrip), Zhang Yiming (Toutiao, 29), Wang Xing (30, Meituan-Dianping), Wang Zhidong (32, Sina)