Find your path to Justin
447 people in our graph share verified history with Justin — schools, employers, funds. One of them is your warm intro.
Garry TanunlockedJustin: together at Y Combinator (2026)
×10Justin: together at Y Combinator
Justin: together at Lynbrook High School
About
Justin So holds a Master's degree in Computer Science from the University of Pennsylvania and previously worked in a finance role at Arm. He is co-founder and CEO of Sidekick.
Founder at SidekickYC S26
Intro paths
YC
Justin went through Y Combinator (Summer 2026) — 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 Sidekick's batch and knows the company first-hand. YC profile ↗
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In turn, Justin can intro founders to Sidekick's investors below.
Experience
- Sidekick (YC S26)Founder and CEOcurrent2025 — presentSan Francisco, CA
- ArmFinance Analyst2025 — 2026San Jose, CA
Skills & more
Python (Programming Language)2Microsoft PowerPointMicrosoft ExcelMicrosoft OutlookFinancial Analysis1InvestmentsFinancial ModelingEconomicsDue Diligence1Business AnalysisAccountingLeadership4
+4 more
TeamworkProblem SolvingPersistenceAnalytical SkillsLanguages English · Korean · Spanish
From Justin's professional profile.
Frequently asked questions
- Who is Justin So?
- Justin So holds a Master's degree in Computer Science from the University of Pennsylvania and previously worked in a finance role at Arm. He is co-founder and CEO of Sidekick.
- Where does Justin So work?
- Justin So is Founder of Sidekick.
- What companies did Justin So found?
- Justin So founded Sidekick.
- Where did Justin So go to school?
- Justin So studied at Y Combinator; University of Pennsylvania (Master's degree, Computer Science); UC Santa Barbara (Bachelor's degree, Economics).
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
UC Santa Barbara mafia179
Also came through, then founded or led a company.
Logan GreenBAFounded LyftNils ReggeBAFounded Developx +2Michael WitzbaFounded Mob Science +2Zheng XuPh.D.Founded SolarCity +1Anita KhamvongsaBachelor of Arts (B.A.)Founded Venbrook +1David J. PhillipsB.A.Founded Fondo +1
+ 172 more
Lynbrook High School mafia19
Also came through, then founded or led a company.
Ritik MalhotraHigh School DiplomaFounded Savvy +2Sahil HasanFounded Dots +1Alex LinFounded Hush +1Anish DharHigh SchoolFounded HomeRoom +1Rani MavramHigh SchoolFounded CompleteVikranth SrivatsaFounded Sunpia
+ 12 more
Arm mafia17
Also came through, then founded or led a company.
Bruce BeckloffVP Corporate Development, VP Investor Relations, Director of Segment MarketingFounded YellowDogYoung SohnBoard of Director and Chairman of Asia Advisory BoardFounded Walden CatalystHiro YoshikawaVP & GM, Data Business UnitFounded TreasureOliver GunasekaraVP, Global Head of Corporate DevelopmentFounded Impossible MetalsDiederik VinkMPG Architecture and Modelling InternFounded nCompass TechnologiesOliver SilversteinCloud Engineering InternFounded Opencall
+ 10 more
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 Pennsylvania1,419
Brian ActonCo-founder of WhatsApp; co-founder of Signal FoundationKunal BahlCo-founder of Snapdeal; co-founder of Titan CapitalDasha MaggioPartner at Felicis Ventures, writer on venture capital and founder psychologyNancy WangInvestor at Felicis VenturesLeah von SiemensPartner at Manta Ray VenturesEghosa OmoiguiFounder and Managing General Partner at EchoVC Partners
+ 1,413 more
Also attended UC Santa Barbara493
Logan GreenCo-founder of LyftJen WangDeal Operations Manager at Felicis VenturesArturo LitvinHead of Global Portfolio Development at Intel CapitalKevin ThauInvestor at Spark CapitalErica DelamareInvestor at DaphniDanielle RomanowskiExecutive Assistant at Sapphire Ventures
+ 487 more
Also attended Lynbrook High School27
Damir BecirovicInvestor at Index VenturesHelen SunAnalyst at Pangaea Ventures Us Inc.Akshay NathanEngineering Manager at Asymmetric Capital PartnersLynn Stepovich CarterOperating Partner, Talent & Growth at Operator CollectiveKevin TuPartner at DFJMeirav Har NoyFounder, Managing Partner at Moneta VC
+ 21 more
Shared employers
Also worked at Arm58
Simon SegarsExecutive Advisor at Black Opal VenturesEileen TanghalFounder & Managing Director at Black Opal VenturesJason ZajacPartner Champion to LegalEase & Parent Voices Oakland at Silicon ValleyBruce BeckloffCo Founder & CEO at Bloc VenturesMichael DimelowCCO at Bloc VenturesAndy GreenNon Executive Director at Bloc Ventures
+ 52 more