Rose Bloomin
About Rose Bloomin
Rose Bloomin is co-founder and Executive Director of Plurality Institute, a nonprofit that supports research and technology bridging social divides. She is also a board member of Community Forward SF, and her X profile lists her as its board president. She is based in San Francisco.
Earlier, she was co-founder and CEO of HandUp, a fundraising platform for people experiencing homelessness and poverty in the US. HandUp won the 2015 Webby Award for Best Charity, People's Voice, and Business Insider listed her among its Top 100 People in Tech that year.
Before HandUp she was COO at SuperBetter Labs and a Data Manager for Obama's 2008 presidential campaign. Her X bio also mentions Science Hack Day.
The only angel investment we could confirm from public sources is Mason AI. Crunchbase lists her among the company's investors, and Mason's seed announcement names her as an angel, describing her as co-founder of Plurality Institute. We found no public statement from her on check size, fund size or the number of angel investments she has made.
Mason AI raised a $4.3M seed round, which the Lounge deals desk dates to March 2026. The company's announcement says the round was oversubscribed and led by Urban Innovation Fund. Crunchbase describes Mason as a San Francisco company with an AI-powered platform for automating building reviews, with categories including construction and document management.
Outside investing, her current work is AI-related. Plurality Institute has been hiring for a project to build an LLM-powered chatbot that helps de-escalate conversations on social media. A Cosmos Institute announcement of AI x Truth-Seeking grant winners includes her, as listed on her LinkedIn activity.
She has not published a thesis, preferred stage or check size that we could find. The one confirmed deal is a seed-stage AI company in the built environment. Her operating background is in civic technology, social impact and AI for social cohesion. Founders should ask her directly what she looks for rather than infer it from a single deal.
- Mason AI: San Francisco company building an AI-powered platform for automating building reviews. She invested as an angel in its $4.3M seed round led by Urban Innovation Fund (2026-03).
Investing activity
Rose Bloomin appears in 1 AI deal tracked by the Lounge deals desk. The rounds are mostly Seed, with a median round size of $4M. The most recent is Mason AI (Seed, $4.3M, Mar 2026).
Rose Bloomin most often invests alongside Urban Innovation Fund, Adam Cohen, Brian McClendon and Zachary Rosen, and the companies they back on Lounge are mostly in AI.
Deals
Frequently asked questions about Rose Bloomin
Who is Rose Bloomin?
Rose Bloomin is co-founder and Executive Director of Plurality Institute and the former co-founder and CEO of HandUp. She is based in San Francisco and invests as an angel.
What AI startups has Rose Bloomin invested in?
The public record shows Mason AI, an AI platform for automating building reviews. She was named as an angel in its $4.3M seed round, which the Lounge deals desk dates to March 2026.
What is Rose Bloomin's check size?
She has not made a check size public, and we found no reliable source for one. Ask her directly.
What stage does Rose Bloomin invest in?
The only confirmed investment is a seed round. She has not published a stated stage preference.
Has Rose Bloomin founded companies?
Yes. She co-founded HandUp, a fundraising platform for people experiencing homelessness and poverty, where she was CEO. She also co-founded Plurality Institute, a nonprofit.
How can founders contact Rose Bloomin?
She is on LinkedIn at linkedin.com/in/rosebroome and on X as @rosical. We found no personal website.
Is Rose Bloomin an angel investor?
Yes. Rose Bloomin invests personally as an angel.
What AI companies has Rose Bloomin invested in?
Rose Bloomin's AI investments include Mason AI. The 1 round on Lounge are listed on this page with amounts, dates and co-investors.
What stage does Rose Bloomin invest at?
In the rounds tracked on Lounge, Rose Bloomin has invested at Seed, with a median round of $4M.
Who does Rose Bloomin co-invest with?
Rose Bloomin's most frequent co-investors on Lounge are Urban Innovation Fund (1 deal), Adam Cohen (1 deal), Brian McClendon (1 deal), Zachary Rosen (1 deal) and David Braginsky (1 deal).