# Justin Rosenthal

> Principal Engineer at The GP

Location: San Francisco, California, United States
Profile: https://flows.cv/justinrosenthal

## Work Experience
### Principal Engineer @ The General Partnership
Jan 2022 – Present

### Principal Engineer @ Sweat Equity Ventures
Jan 2021 – Jan 2022

### Lead Software Engineer @ Google
Jan 2017 – Jan 2021 | San Francisco

### Senior Principal Software Engineer @ Yahoo
Jan 2014 – Jan 2017
- Initial tech lead for Yahoo Livetext: architected and developed server infrastructure, oversaw early native mobile app development.
- Managed direct reports: 1-on-1’s, performance reviews, promotions.
- Designed and led development of a realtime, distributed messaging backend -- the first ever production service written in Go at Yahoo.
- Built and deployed a globally distributed, elastic WebRTC server infrastructure.
- Tech lead for Yahoo Sports Reel.

### Co-Founder / CTO @ MessageMe
Jan 2012 – Jan 2014 | San Francisco
- Recruited and managed a team of 8 engineers across various disciplines: backend, iOS, Android, and web.
- Built and operated our custom asynchronous messaging stack that delivered millions of messages, photos, doodles, songs, and videos per day.
- Architected and wrote much of our iOS application, focusing primarily on the model & networking layers, as well as general app performance.
- Designed and maintained our in-house analytics pipeline.
- Served as half of a 2-person ops team, responsible for the uptime of our service: deploys, monitoring, scaling, failover, etc.

### Director of Engineering @ LOLapps (Acquired by 6Waves)
Jan 2011 – Jan 2012
- Managed entire engineering organization (20 engineers across 4 teams).
- Oversaw hiring for all technical positions.
- Handled technical due diligence for the internal merger and an external acquisition.

### Software Engineer @ LOLapps (Acquired by 6Waves)
Jan 2009 – Jan 2011
- Lead developer on Ravenwood Fair.  Built out team from 2 to 15.  Managed 3 direct reports, coordinated between multiple disciplines.
- Took ownership over 2nd largest product (Gift) within 3 months of joining the company.  Subsequently rewrote entire codebase in Python and transitioned the live product off PHP infrastructure.
- Scaled the Gift product to 5+ million DAU and 50+ million daily gifts sent.


## Education
### MS in Biomedical Engineering
University of Wisconsin-Madison

### BS in Computer Engineering
University of Wisconsin-Madison


## Contact & Social
- LinkedIn: https://linkedin.com/in/rosenthaljustin

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Source: https://flows.cv/justinrosenthal
JSON Resume: https://flows.cv/justinrosenthal/resume.json
Last updated: 2026-04-12