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Castle vs Island

Side-by-side founder and growth signal comparison.

Castle logoC
Castle Team

Castle

Castle Team

Island logoI
Island Team

Island

Island Team

MetricCastleIsland
FounderCastle TeamIsland Team
CountryUnited StatesUnited States
Total Funding$9.00M$250.00M
Last RoundSeries A Khosla Ventures, $9M Series A in 2019Series E Sequoia, $250M Series E in 2025, $4.8B valuation
Hiring RolesOpen RolesOpen Roles
IndustryCybersecurityCybersecurity
StageSeries ASeries E
HeadquartersSan Francisco Bay Area, California, USADallas, Texas, USA
Employee Count11-50 employees101-200 employees
Tech StackAWS, React, Python, PostgreSQLAWS, React, Python, PostgreSQL
Open CastleOpen Island