Jack Mastrangelo
FounderFounder at Cobblestone
New York, New York, United States
FoundedCobblestone · YC
About
Jack Mastrangelo is a cofounder of Cobblestone who previously worked as a software engineer at Ramp and Facebook.
Founder at CobblestoneYC W23
Intro paths
YC
Jack went through Y Combinator (Winter 2023) — any YC alum in your network can reach them through the YC community.
GP
Their group partner at YC was Jared Friedman, YC Group Partner — the partner who ran Cobblestone's batch and knows the company first-hand. YC profile ↗
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In turn, Jack can intro founders to Cobblestone's investors below.
Cobblestone's investors · 2
Co-founders at Cobblestone
JS
Jason ScharffFounder
Experience
- MoabDirector of Engineeringcurrent2026 — presentNew York, NY
- 100Advisorcurrent2025 — present
- CrosbyFounding Engineer2025 — 2026New York City Metropolitan Area
- CobblestoneCo-Founder, CTO (YC W23, Acquired by 100)2023 — 2025New York City Metropolitan Area
- RampSenior Software Engineer2022New York City Metropolitan Area
- RampSoftware Engineer2021 — 2022New York, United States
- FacebookSoftware Engineer2020 — 2021New York, United States
- GatherlySoftware Engineer2020Atlanta, Georgia, United States
- Northeastern UniversityFundamentals of Computer Science Teaching Assistant2017 — 2020Greater Boston Area
- GoogleSoftware Engineer Intern2019Irvine, California
- FacebookSoftware Engineer Intern2019Menlo Park, California
- PlacePassFull-stack Developer Co-op2018Greater Boston Area
- Northeastern UniversityHonors Early Research Assistant2016 — 2017Greater Boston Area
- NYU Polytechnic School of EngineeringIntern2016
Skills & more
Java2Ruby on RailsReact.jsC#Google AnalyticsMixpanelAmazon EMRAmazon S3Amazon Web Services (AWS)Elastic BeanstalkCustomer Service1OCaml2
+9 more
Functional ProgrammingObject-Oriented Programming (OOP)CompilersElmGoogle Tag ManagerHerokuHiveLeadershipRacketFrom Jack's professional profile.
Frequently asked questions
- Who is Jack Mastrangelo?
- Jack Mastrangelo is a cofounder of Cobblestone who previously worked as a software engineer at Ramp and Facebook.
- Where does Jack Mastrangelo work?
- Jack Mastrangelo is Founder of Cobblestone.
- What companies did Jack Mastrangelo found?
- Jack Mastrangelo founded Cobblestone.
- Where did Jack Mastrangelo go to school?
- Jack Mastrangelo studied at Northeastern University (Bachelor of Science (B.S.), Mathematics and Computer Science).
Founder mafias
Y Combinator mafia8,773
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Sam AltmanPresidentFounded Tools for Humanity +3Jessica LivingstonCo-founderFounded Y CombinatorAlexis OhanianYC Summer 2005Founded RedditFred EhrsamYC Summer 2012Founded Nudge +1Matt HuangYC Winter 2011Founded HotspotsTrae StephensYC Winter 2022Founded Pursuit +1
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Northeastern University mafia43
Also came through, then founded or led a company.
James SteinbergBachelor's degreeFounded OpenShelf +2Luke ZaientzBSFounded Reigning Champs +1Vicente ZavarceBachelor’s DegreeFounded Yummy +1Kahlil LaljiBachelor's of ScienceFounded Natural +1Kasey ZhangBachelor of ScienceFounded Gulp +1Tim McCarthyBachelor of ScienceFounded Spring Loaded Technology +1
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Ramp mafia21
Also came through, then founded or led a company.
Ian TraceySenior Staff Software Engineer, Applied AIFounded Hydrant +1Royce ArockiasamyApplied AI EngineerFounded Pleom +1Karim AtiyehCo-Founder, Co-CEO RampFounded Paribus +1Austin HayHead of Marketing TechnologyFounded ClarifyKingsley AdvaniInvestorFounded AllocationsDaniel BessonovInternFounded Avora
+ 14 more
Ramp mafia19
Also came through, then founded or led a company.
Ian TraceySenior Staff Software Engineer, Applied AIFounded Hydrant +1Royce ArockiasamyApplied AI EngineerFounded Pleom +1Daniel BessonovInternFounded AvoraMichael LiuProduct ManagerFounded FinaryJosh WrightStaff Software EngineerFounded ApolloMoritz PailSoftware EngineerFounded Mine
+ 12 more
Same school
Also attended Northeastern University261
Matt GuineyChief Financial Officer at Flybridge Capital PartnersSaunaz MoradiPartner, Communications at Lux CapitalBrian DixonManaging Partner at Kapor CapitalMurat BicerGeneral Partner at CRV (Charles River Ventures)Arjun BalajiPartner, Investing & Research at ParadigmAyesha AroraVenture Partner at S32
+ 255 more
