Co-founder, CTO at Upstream Security
Intro paths
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In turn, Yonatan can intro founders to Upstream Security's investors below.
Upstream Security's investors · 10
Alliance VenturesAmsterdamBMW i VenturesMountain View · $10M checksCisco InvestmentsSan JoseConnect VenturesLos AngelesCRV (Charles River Ventures)Bay Area · $250K – $5M checksGlilot Capital PartnersHerzliya · $1.5M – $70M checksManiv MobilityTel Aviv · $2M – $126M checksRoosh VenturesKiev · since 2026Volvo Group Venture Capital ABGothenburg · $1.1M – $10.8M checksY CombinatorSan Francisco · $500K checks · since 2026
Co-founders at Upstream Security
YL
Yoav LevyCo-founder, CEO
Experience
- Glilot Capital PartnersMembercurrent2019 — present
- Upstream SecurityCo-Founder and CTOcurrent2016 — present
- MicrosoftSenior Development Lead2009 — 2016
- Israeli High-Tech CompaniesSecurity Consultant2009
- ImpervaSenior Product Manager2006 — 2009
Skills & more
Network SecurityLeadership
From Yonatan's professional profile.
Frequently asked questions
- Who is Yonatan Appel?
- Co-founder, CTO at Upstream Security
- Where does Yonatan Appel work?
- Yonatan Appel is Co-founder, CTO of Upstream Security.
- What companies did Yonatan Appel found?
- Yonatan Appel founded Upstream Security.
- Where did Yonatan Appel go to school?
- Yonatan Appel studied at Tel Aviv University (Bachelor of Laws (LL.B.)); The Open University of Israel (Bachelor of Arts (B.A.), Computer Science).
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Founder mafias
Tel Aviv University mafia284
Also came through, then founded or led a company.
Kristo KäärmannBachelor’s of scienceFounded TransferWise +2Aviv EyalB.CSFounded Skillful +2Nir ZoharBSc. EE.Founded Chakratec +2Eyal ShinarFounded Black Ore Technologies +1Irit YanivMBAFounded Digma Medical +1Ofer ShapiroM.ScFounded Quantumpulse +1
+ 277 more
The Open University of Israel mafia43
Also came through, then founded or led a company.
Ilya SutskeverComputer ScienceFounded Safe Superintelligence +1Ron GuraBachelor’s DegreeFounded EmpathyYan M.MathematicsFounded Aptos Orbital +1Gal AgaBAFounded Aligned +1Tzvika PerelmuterBachelor of Science (BSc)Founded Capstack +1Shay FinkelsteinComputer Science and Business ManagementFounded Securitize
+ 36 more
Imperva mafia14
Also came through, then founded or led a company.
Amichai ShulmanCo-Founder & CTOFounded Kanopy Security +1Mark KraynakSVP & General Manager, Enterprise SolutionsFounded EarlyPatrick MassetAVP Sales NortheastFounded AIIMMickey BoodaeiCo-FounderFounded Transmit SecurityShlomo KramerCo-Founder, President & CEO (early years)Founded Cato NetworksRajaram SrinivasanSenior Product ManagerFounded Unbound
+ 7 more
Glilot Capital Partners mafia7
Also came through, then founded or led a company.
Same school
Also attended Tel Aviv University621
Arnon DinurPartner at 83NorthYoram SnirPartner at 83NorthRaz MaysharSenior Manager at Qualcomm VenturesDavid GoldschmidtManaging Director, Head of the Fund at Samsung Catalyst FundAmit ShofarSr. Investment Director at Samsung Catalyst FundRutie AdarInvestments & Innovation Sr. Director, Israel at Samsung Catalyst Fund
+ 615 more
Also attended The Open University of Israel74
Ilya SutskeverCo-founder of OpenAI; co-founder & CEO of Safe SuperintelligenceRon GuraCo-founder & CEO of EmpathyRutie AdarInvestments & Innovation Sr. Director, Israel at Samsung Catalyst FundShay FinkelsteinCTO & Co-founder at Collective LiquidityLidia VerraBookkeeper at TriventuresAdi GreenwaldAssociate at YL Ventures
+ 68 more
Shared employers
Also worked at Upstream Security8
Erik JohanssonInvestment Director at Volvo Group Venture Capital ABKobi SambourskyCo-Founder and Managing Partner at Glilot Capital PartnersArik KleinsteinCo-Founder and Managing Partner at Glilot Capital PartnersKasper SageManaging Partner at BMW i VenturesMike GranoffFounder and Managing Partner at Maniv MobilityAtanas MukovPartner at Walter Ventures
+ 2 more
Also worked at Microsoft1,812
Reid HoffmanCo-founder of LinkedIn; Partner at GreylockGarry TanPresident & CEO of Y CombinatorNat FriedmanCo-lead of Meta Superintelligence Labs; co-founder of NFDGKai-Fu LeeChairman of Sinovation Ventures and CEO of 01.AIBill GatesCo-founder of Microsoft; Chair of the Gates FoundationMike KriegerCo-founder of Instagram; Chief Product Officer at Anthropic
+ 1,806 more
