David Day
InvestorFounderFellow at Founders · Cofounder and CTO at LunaBill
San Francisco, California, United States
FoundedLunaBill · YC
Find your path to David
575 people in our graph share verified history with David — schools, employers, funds. One of them is your warm intro.
Garry TanunlockedDavid: together at Y Combinator (2025)
×11David: together at Y Combinator
About
David Day founded Skiesoft, an AI transcription company based in Taiwan, and previously worked as a data scientist at UCSF developing models for medical coding validation.
Cofounder and CTO at LunaBillYC F25
Intro paths
YC
David went through Y Combinator (Fall 2025) — any YC alum in your network can reach them through the YC community.
GP
Their group partner at YC was Aaron Epstein, General Partner at Y Combinator — the partner who ran LunaBill's batch and knows the company first-hand. YC profile ↗
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In turn, David can intro founders to LunaBill's investors below.
LunaBill's investors · 5
Co-founders at LunaBill
SP
Suhail ParryCofounder and CEO
Experience
- LunaBill (YC F25)Co-Foundercurrent2025 — presentSan Francisco, California, United States
- Healthcare Financial Management Association (HFMA)Membercurrent2025 — presentCalifornia, United States
- Founders, Inc.Fellowcurrent2024 — presentSan Francisco, California, United States
- University of California, San FranciscoData Scientist2023 — 2024San Francisco, California, United States
- Google Developer Student ClubsFounder2023 — 2024San Francisco, California, United States
- Skiesoft Corporation LimitedFounder2021 — 2023Taipei City, Taiwan
Skills & more
React Native1MATLAB1Health InformaticsTinyMLReal-time MonitoringSignal ProcessingEmbedded SystemsComputer VisionRoboticsPHPTypeScriptNode.js
+12 more
Python (Programming Language)Natural Language Processing (NLP)Machine LearningStatisticsR (Programming Language)Deep LearningData VisualizationArtificial Intelligence (AI)SoftwareSoftware ArchitectureWeb DevelopmentData Science- CITI Good Clinical Practice Course — CITI Program
- Social and Behavioral Responsible Conduct of Research Course — CITI Program
- Human Subjects Protection Training — CITI Program
- Biomedical Responsible Conduct of Research Course 1. — CITI Program
From David's professional profile.
Colleagues at Founders
Addison Leong
Venture Partner at DCM Ventures
Adrianna Lakatos
Portfolio & Ecosystem at Founders
Aiden Blumenstein
Programs & Storytelling at Founders
Anna Kravets
Mentor Advisor at PharmStars Ventures
Anna Wang
Principal at GreyMatter
Brian Singerman
General Partner at Founders
Dante Lentini
Growth at Founders
Furqan Rydhan
Entrepreneur + Investor + Technologist
Frequently asked questions
- Who is David Day?
- David Day founded Skiesoft, an AI transcription company based in Taiwan, and previously worked as a data scientist at UCSF developing models for medical coding validation.
- Where does David Day work?
- David Day is Cofounder and CTO of LunaBill and Fellow at Founders.
- What companies did David Day found?
- David Day founded LunaBill.
- Where did David Day go to school?
- David Day studied at Y Combinator; University of California, San Francisco (Master of Science - MS, Health Data Science); National Central University (Bachelor of Science - BS, Computer Science).
Founder mafias
Y Combinator mafia10,230
Also came through, then founded or led a company.
Sam AltmanPresidentFounded Tools for Humanity +3Garry TanPresident & CEOFounded Y Combinator +1Jessica LivingstonCo-founderFounded Y CombinatorAlexis OhanianPartnerFounded RedditFred EhrsamYC Summer 2012Founded Nudge +1Matt HuangYC Winter 2011Founded Paradigm +1
+ 10,223 more
University of California, San Francisco mafia78
Also came through, then founded or led a company.
Geoffrey von MaltzahnMSFounded Sienna Biopharmaceuticals +5Dino Di CarloPh.D.Founded Partillion +3Luke EvninPhDFounded Mpmcapital +1Alec NielsenBiophysicsFounded Asimov +1Aditya KohliDoctor of Philosophy (Ph.D.)Founded Phathom Pharmaceuticals +1William GreeneMDFounded Pear Therapeutics +1
+ 71 more
Founders mafia23
Also came through, then founded or led a company.
Huzaifa AhmadStudio Software EngineerFounded Parameter +1Peter ThielGeneral PartnerFounded PayPal +1Trae StephensGeneral PartnerFounded Pursuit +1Furqan RydhanFounderFounded ThirdwebCG ChenFounder in ResidenceFounded Ruta HealthOscar RojasStudio FounderFounded Nara
+ 16 more
National Central University mafia3
Also came through, then founded or led a company.
Same school
Also attended Y Combinator2,000
Tarek MansourCo-founder & CEO of KalshiSuhail DoshiFounder of Mixpanel; founder of ParticleSubomi OluwalanaCo-founder & CEO of ConvoyArhaan A.Deeptech Fellow at Clear VenturesCollin WallaceGeneral Partner at Lobby CapitalVictor SantosVictor Scout at One Way Ventures
+ 1,994 more
Also attended University of California, San Francisco170
Douglas CrawfordManaging General Partner at Mission BiocapitalLuke EvninAdvisor at MPM BioImpactCharles White, Ph.D.Principal at Illumina VenturesMatt MaurerInvestor at WVV CapitalAlec NielsenFounder & CEO, Asimov & Venture Partner at Pillar VCStephan ChristgauFounding Partner at EIR Ventures
+ 164 more
Shared employers
Also worked at LunaBill (YC F25)1
Also worked at Healthcare Financial Management Association (HFMA)2
Also worked at University of California, San Francisco180
Logan HilleLife Sciences Analyst at CincyTechPaul JennyBoard Chair at CincyTechFrancisco GimenezInvestment Team at 8VCUlrik B. NielsenGeneral Partner at Mission BiocapitalHani GoodarziFounder, Tahoe Therapeutics at Amplify PartnersCharles White, Ph.D.Principal at Illumina Ventures
+ 174 more