Michael Seibel

Startup founder and Y Combinator Partner Emeritus

Michael Seibel co-founded Justin.tv and Socialcam and spent more than a decade advising early-stage founders through Y Combinator.

Startup fundraisingFounder coachingEarly-stage startupsProduct-market fit

Why BuildOS listens

BuildOS listens to Michael because his fundraising advice comes from both sides of the exchange: building venture-backed startups and reviewing, interviewing, and advising founders at Y Combinator. His cold-investor-email guidance is used only for the outreach skill’s investor mode, where short factual context and a reply-first ask are more appropriate than a sales cadence.

Editorial standard

Inclusion means BuildOS reviewed useful public material and can trace specific processes back to it. It does not mean the person reviewed, approved, or endorses the resulting skill.

Skills informed by this work

BuildOS currently traces 1 reviewed source across 1 published skill.

1 reviewed source

Cold Email Engagement-First Outreach

A source-lineaged root combo skill for planning, drafting, auditing, and rewriting cold outreach. Distilled from seven cold-email source analyses into one master playbook for high-volume campaigns, strategic accounts, single-target relationship outreach, reply revival, investor fundraising, founder-led outreach, recruiting, PR, partnerships, and customer research.