Castle Island Ventures
Venture capitalActively deployingBoston · Pre-Seed–Series A · 12 people tracked
Also known as CASTLE ISLAND MANAGEMENT, LLC
Investment thesis
Castle Island Ventures invests exclusively in public blockchain technologies, supporting entrepreneurs building the infrastructure and application companies needed to help these protocols reach their potential. The firm targets early-stage companies operating at the intersection of traditional finance and public blockchains, with a focus on accelerating frictionless finance.
Source: firm website, verified Aug 25, 2026.
Team · 12 people
from the firm's website & curated
What they invest in
from 33 of 42 portfolio companiesCrypto & Web3 ×26Fintech ×23Data & Infrastructure ×7Enterprise Software ×7AI & Machine Learning ×5Cybersecurity ×5SaaS ×5Cloud Computing ×2
HQs:United States×19United Kingdom×1
Who they back
founder profiles across 16 portfolio companiesFounding team size:solo founder×52 founders×63 founders×34+ founders×2
Where their founders studiedfrom 13 founders with education data
Dartmouth College ×2Massachusetts Institute of Technology ×2
Where their founders worked beforefrom 13 founders with career history
Revolut ×3McKinsey & Company ×2
Accelerator rootsportfolio companies that came through a program
Investments · 42 tracked
founders shown can be your intro pathBy year:2026 · 52025 · 42024 · 32023 · 214 dated
Phylax builds the Credible Layer, a policy engine that lets on-chain protocols declare states they must never reach and enforces circuit breakers that reject transactions crossing those limits.
Crypto & Web3CybersecurityEnterprise Software
Co-investorsBreedFigmentHash3 Capital
Sealance builds The Sealance Trust Platform, a compliance and identity-verification system that uses zero-knowledge proofs and applied cryptography to enable privacy while enforcing regulatory compliance for the cryptocurrency industry.
AI & Machine LearningCrypto & Web3CybersecurityFintech
Shlomit Azgad-Tromer(Co-founder)Matthew Green(Co-founder)Eran Tromer(Co-founder)
Co-investorsFireblocksRibbit CapitalCoinbase VenturesDigital Currency GroupJump Capital
XFX operates a liquidity layer that provides unified fiat and stablecoin liquidity with intelligent routing and near-instant settlement, letting institutions trade across fiat and stablecoin pairs without pre-positioning capital.
Crypto & Web3Data & InfrastructureFintechMiami, US
Santiago Alvarado(Co-founder & CEO)
Co-investorsHaun VenturesOak HC/FTCoinbase VenturesMAYA CapitalMAYA Capital Ventures
Coin Metrics provides market and on-chain data, reference rates, and indexes for crypto and digital assets, delivered to institutional investment teams via APIs.
Crypto & Web3Data & InfrastructureFintechBoston, US
Timothy Rice(Executive Officer, Director)Tim Rice(Founder)in
BoardMathew S. McDermott(Director)Sean Judge(Director)inMatt Scott Walsh(Director)in
Board seatNic Carter· per SEC Form D · $6.7M raise · filed Oct 2023
Co-investorsAcrew CapitalCoinbase VenturesCollab+CurrencyCommunitas Capital PartnersDigital Currency GroupDragonfly+2 more
Miami, US
Board seatSean Judge· per SEC Form D · $20M raise · filed Jul 2026
Parry integrates software, hardware, and autonomy at the edge to turn complex technologies into mission-ready systems for contested defense environments.
Deep TechDefense TechRoboticsAlexandria, US
Jon Pilon(Executive Officer)Aydin Mohtashamian(Executive Officer)John D Parkes(Executive Officer, Director)
BoardRobert Miller(Director)David Gross(Director)
Board seatGus Coldebella· per SEC Form D · $90.7M raise · filed Nov 2024
Co-investorsTeamworthy Ventures
Surus is a financial infrastructure platform offering qualified custody, reserve management, and token issuance for digital asset builders, backed by its own North Carolina-chartered trust company.
Crypto & Web3Data & InfrastructureFintechWashington, US
Bradley Gibson(Chief Technology Officer)inBethany Wheeler(Chief Trust Officer)inJennifer Hoopes(Chief Legal Officer)inRachel Trujillo(Chief Compliance Officer)inPatrick Murck(Executive Officer, Director)in
Board seatNic Carter· per SEC Form D · $10.6M raise · filed Mar 2025
Co-investorsFinancial Venture StudioProtagonistRestive Ventures
A DeFi protocol creating a marketplace for blockspace.
Co-investorsCoinbase Ventures1kxCircle VenturesDragonflyRobot VenturesTribe Capital
Alpen Labs builds a Bitcoin layer-2 network that enables financial applications through a ZK rollup with optimistic bridge architecture.
Crypto & Web3FintechNew York City, US
Abishkar Chhetri(Founder)Pramod Kandel(Founder)Simanta Gautam(Founder)John LightTrey Del BonisLiam Eagen
Co-investorsHivemind Ventures, LlcLaunchpad CapitalMirana VenturesResolute VenturesSTILLMARKAsymmetric+3 more
Andrena is a wireless Internet service provider that delivers high-speed connectivity to multi-tenant buildings and households using wireless technology beamed to building roofs, then distributed wirelessly to units.
CleantechCloud ComputingNew Jersey, US
Neil Chatterjee(Founder)James Smits(Founder)in
Co-investors645 VenturesAfore CapitalBollinger Investment GroupCalm VenturesChaos VenturesChapter One+7 more
Co-investorsArrington CapitalLemniscapPantera CapitalArrington XRP Capital
Tools offering users secure financing against their cryptocurrency holdings.
Arch Lending (legal entity ChainFi, Inc) offers crypto-backed loans to U.S. borrowers and businesses, using digital assets as collateral.
Crypto & Web3FintechNew York, US
Dhruv Patel(Founder)inHimanshu Sahay(Founder)in
Co-investorsFormus CapitalFour Acres CapitalPICUS CAPITAL
ARQ Finance (formerly DolarApp) is a digital financial platform that enables currency exchange to digital dollars and euros, international payments, and investment access to global markets.
Crypto & Web3FintechLondon, GB
Fernando Terrés(CEO and co-founder)inZach Garman(Founder)inAlvaro Correa(Founder)inÁlvaro Correa Gallardo(Founder)
Co-investorsFounders FundSequoia CapitalY Combinator
Arx develops secure chips that embed blockchain authentication into physical items like apparel, collectibles, and certificates, enabling decentralized provenance verification and digital experiences without centralized servers.
Crypto & Web3Deep TechHardware
Co-investorsInflection.xyzPlaceholder VC1kxPlaceholderSeed Club Ventures
Asymmetry Finance is a decentralized finance protocol that lets users borrow stablecoins (USDaf and AmpUSD) against BTC or stablecoin collateral at customizable fixed interest rates.
Crypto & Web3Fintech
Co-investorsF-Prime CapitalMagnus CapitalSilvermine CapitalAvon VenturesEcco Capitalgmjp+1 more
Delivers decision-grade intelligence on U.S. banks by integrating regulatory filings, securities data, and property deed information.
Atrium is an AI-powered analytics platform that unifies bank filings, real estate lending data, county records, and earnings-call transcripts to provide loan-level intelligence for credit due diligence, CRE and multifamily portfolio exposure analysis, and risk assessment.
AI & Machine LearningData & InfrastructureFintech
Attestiv offers an AI-powered platform that validates digital files—photos, videos, audio, and documents—to detect tampering, deepfakes, and fraud using rules-based and machine learning models, delivered via a dashboard, APIs, and SDKs.
AI & Machine LearningCybersecurityInsurTechLehi, US
Nicos Andrew Vekiarides(Executive Officer, Director)John Whitney Bates(Executive Officer, Director)Nicos VekiaridesinJohn BatesinThomas Mark Morley(Executive Officer)Emmanuel Parasirakis(Executive Officer)
Co-investorsBorderless VenturePlug and Play Ventures
Babylon Labs develops trustless infrastructure that enables Bitcoin to be used as collateral in decentralized finance and through a Bitcoin staking protocol for blockchain validation.
Crypto & Web3
Fisher Yu(Founder)
Co-investorsa16z cryptoAlumni VenturesAndreessen HorowitzBasecamp FundHack VCIOSG Ventures+3 more
A global payments network enabling consumers and businesses to transact in any currency, anywhere on earth.
Bitwise offers professionally managed crypto investment funds and products, including ETFs, separately managed accounts, private funds, and staking.
Crypto & Web3FintechSan Francisco, US
Hong Kim(Executive Officer, Director)Hunter Horsley(Founder & CEO)inKatherine Dowling(Executive Officer)Matt Hougan(Executive Officer)Teddy Fusaro(Executive Officer)
BoardCorey Mulloy(Director)
Co-investorsBlockchain CapitalChorus OneCoinbase VenturesCraft VenturesDria VenturesElectric Capital+5 more
Coala Pay provides a settlement layer and payment infrastructure for humanitarian and development aid programs, handling institutional grants, household cash transfers, frontline worker payments, and vendor settlements.
Crypto & Web3FintechImpact & Social Good
Co-investorsCV VCLattice CapitalReflexive CapitalCommerce VenturesFactor Capital
Eaglebrook is a crypto investment platform for wealth managers, offering tax-optimized Bitcoin, Ethereum, and multi-asset separately managed accounts (SMAs) held in segregated accounts at qualified custodians.
Crypto & Web3FintechSaaS
Christopher King(Founder)in
Co-investorsBrewer Lane VenturesF-Prime CapitalAvon VenturesFranklin TempletonGemini Frontier FundJump Capital
Erebor is a US national bank in Columbus, Ohio serving AI, crypto, defense and advanced manufacturing companies.
Co-investorsAntiArctic DigitalBalerion Space VenturesIneffable VenturesLakeside CapitalLux Capital+5 more
Felix is a remittance service that enables users to send money from the United States to Latin America (Mexico, Guatemala, Honduras, El Salvador, and Dominican Republic) via WhatsApp, with funds delivered to bank accounts, mobile wallets, or cash pickup locations.
B2B MarketplacesFintechSan Francisco, US
Bernardo Garcia(Founder)
Co-investorsContour Venture PartnersDorm RoomMONASHEESQED InvestorsSwitch VenturesThe MBA Fund+4 more
Groma issues GromaCoin, a blockchain token where each coin is a tokenized share in the Groma Real Estate Trust, backed by income-producing US real estate held in a regulated structure.
Crypto & Web3FintechPropTech
Chris Lehman(Founder)Grant Fishman(Founder)in
Co-investorsBantam GroupCoinbase VenturesLaunchpad Venture Group
Hoseki provides cryptographic verification of Bitcoin and digital asset holdings, letting holders generate verifiable proofs of ownership and businesses request and verify counterparty holdings without exposing addresses or sensitive data.
Crypto & Web3FintechSaaS
Sam Abbassi(CEO)Cory Wilbur(CTO and Head of Product)in
Co-investorsF-Prime CapitalFulgur VenturesSTILLMARKAvon VenturesTen31
Kintsu is a liquid staking protocol on the Monad blockchain that lets users stake MON tokens and receive sMON liquid staking tokens usable across DeFi for trading, lending, and pooling while earning staking and MEV yield.
Crypto & Web3Fintech
Connor McKenzie(Founder)in
Co-investorsNxGenPragma VenturesReciprocal VenturesBrevan Howard Digital
Modern Treasury provides a payments infrastructure platform that enables businesses to move and track money across fiat and stablecoin rails through a single API.
Crypto & Web3Developer ToolsEnterprise SoftwareFintechSaaSSan Francisco, US
Matt Marcus(Co-Founder & CEO)inDimitri Dadiomov(Cofounder & CEO)inSam Aarons(Co-Founder & CTO)in
Co-investorsArchetypeArtisanal VenturesCleo CapitalMischiefNewView CapitalQuiet Capital+7 more
Nirvana Labs operates a high-performance cloud platform offering bare metal compute, accelerated block storage, private networking, and managed Kubernetes orchestration for latency-sensitive, data-heavy systems.
Cloud ComputingData & InfrastructureEnterprise Software
Co-investorsCrucible CapitalHash3 CapitalLattice CapitalRaptor GroupJump CryptoRW3 Ventures
Project Eleven builds post-quantum cryptography and migration tooling for Bitcoin, Ethereum and other digital asset networks.
Co-investorsCoinbase VenturesLattice CapitalQuantonationVariant FundBalaji SrinivasanFin Capital+1 more
PYOR provides blockchain data analytics for crypto protocols, DAOs, and institutional investors, offering custom dashboards, risk and governance insights, and developer tools.
Crypto & Web3Data & InfrastructureDeveloper Tools
Co-investorsFuture Perfect VenturesHash3 CapitalAntlerCoinbase VenturesForce Ventures
Ripple builds blockchain-based financial infrastructure to enable cross-border value transfer and payment solutions for enterprises, governments, and financial institutions.
Crypto & Web3Enterprise SoftwareFintechSan Francisco, US
Ryan Fugger(Founder)David Schwartz(Director)inSusan Athey(Director)Gene Sperling(Director)Christian Larsen(Executive Officer, Director, Promoter)Young Guo(Director)
Co-investors500 GlobalAbstract VenturesAurum Venture PartnersAvant Global LLCCamp One VenturesCore Venture Capital+19 more
Station70 builds institutional-grade security products for enterprise asset protection, including private key backup and recovery (Bunker) and secrets management (Gatekeeper).
Crypto & Web3CybersecurityEnterprise SoftwareConcord, US
Adam Healy(Founder)inAdam Everspaugh(Founder)Dr Adam Everspaugh(Founder)
Co-investorsA100X VenturesMetalayerSCB 10XNotation CapitalSemantic Ventures
Talos provides white-label cryptocurrency trading infrastructure and technology for retail investment platforms and digital asset brokerages.
Crypto & Web3Data & InfrastructureFintechSaaS
Anton Katz(Founder & CEO)in
Co-investors10SQ Capital (TenSquared)a16z cryptoAndreessen HorowitzCoinbase VenturesElefundFin Capital+12 more
Tesser provides stablecoin payment infrastructure for financial institutions, including global stablecoin settlement, off-ramp-as-a-service, and stablecoin payment capabilities with wallet infrastructure, on/off ramps, and compliance tools.
Crypto & Web3Enterprise SoftwareFintechNew York City, US
Geetha Panchapakesan(Founder)in
Co-investorsDigital Currency GroupStrobe Ventures
TRM Labs offers an online certification course on blockchain investigations and crypto forensics for professionals who need to trace cryptocurrency transactions across multiple blockchains.
AI & Machine LearningCrypto & Web3CybersecurityEdTechEnterprise SoftwareFintechGovTechSan Francisco, US
Esteban Castaño(Founder)inRahul Raina(Founder)inSujit Raman(Chief Legal Officer)Ari Redbord(Global Head of Policy)Tom Armstrong(Head of Compliance Advisory)
Co-investorsAlumni VenturesB Capital GroupB4 CapitalBasecamp FundBessemer Venture PartnersGeodesic Capital+12 more
Valinor Discovery generates patient-derived datasets combining multi-omics and clinical data to enable machine learning applications in drug development.
AI & Machine LearningBiotechMedical Devices
Co-investorsCampus Founders FundMythos Ventures Management, LlcMaven 11
Valinor is a credit institution building infrastructure for "Open Credit," aiming to connect traditional credit markets with onchain finance.
Crypto & Web3FintechNew York, US
Lily Yarborough(Executive Officer, Director, Promoter)inConnor Dougherty(Executive Officer, Director, Promoter)in
BoardSean Judge(Director)Nazar Khan(Director)
Co-investorsDepartment of XYZMaven 11Venture Dept.
Yellow Card provides digital asset and fiat payments infrastructure that lets banks, financial institutions, corporates, and other businesses access, store, send, and manage stablecoins and make payments across USD and 50+ local currencies.
Chris Maurice(Founder)inJustin Poiroux(Founder)in
Co-investorsAtlanta Technology AngelsDG Daiwa VenturesFenbushi CapitalPharsalus CapitalSony Ventures CorporationSozo Ventures+1 more
ZenLedger provides tax and accounting software that automates cryptocurrency tax calculations for crypto traders, investors, and tax professionals.
Crypto & Web3FintechSaaSSeattle, US
Patrick Larsen(Founder & CEO)Pat Larsen(Co-Founder / CEO)Daniel Escobar(Chief Technology Officer)
BoardMark Casady(Director)in
Co-investorsBloccelerate VCBorderless VentureConvergeKing River CapitalOssian CapitalParaFi Capital+7 more
Rows marked “SEC filing” are inferred from directors named on the company's SEC Form D — public regulatory data, not a portfolio list published by the firm.
Portfolio news
latest coverage across their companiesErebor · finance.yahoo.com · Aug 11, 2026
TRM Labs · cryptopolitan.com · Jul 18, 2026
Ripple Labs · cryptonews.net · Jul 18, 2026
Arx · resiliencemedia.co · Jul 17, 2026
Bitwise · bitcoinworld.co.in · Jul 13, 2026
Groma · crowdfundinsider.com · Jul 6, 2026
ARQ · larepublica.co · Apr 3, 2026
Valinor · finsmes.com · Mar 31, 2026
Frequently asked questions
- How many investments has Castle Island Ventures made?
- Castle Island Ventures has 24 tracked investments, including 2 dated in the last 24 months.
- What stage does Castle Island Ventures invest at?
- Castle Island Ventures invests at the Pre-Seed, Seed, Series A stages.
- What is Castle Island Ventures's typical check size?
- Castle Island Ventures typically writes checks of $100K – $5M.
- What sectors does Castle Island Ventures focus on?
- Castle Island Ventures focuses on Crypto & Web3, Cybersecurity, Enterprise Software, Fintech.
- Where is Castle Island Ventures located?
- Castle Island Ventures is headquartered in Boston, US.
- Does Castle Island Ventures lead rounds?
- Yes, Castle Island Ventures leads investment rounds.
- Who does Castle Island Ventures co-invest with?
- Castle Island Ventures most often shares deals with Coinbase Ventures, SCB 10X, Y Combinator, among 124 tracked co-investors.
From the blog
visit blog ↗Castle Island Ventures publishes weekly roundups covering developments across crypto markets, including security vulnerabilities (Coldcard exploits, quantum risk), regulatory pressures (CLARITY Act, CBDC bans, SEC enforcement), and infrastructure changes (BitMEX shutdown, blockchain patent acquisitions, tokenized settlement pilots). AI summary
Media · Podcasts & interviews
featuring the teamCan Bitcoin Survive AI & Quantum? with Nic Carter | Galaxy Brains
Galaxy · Nic Carter
The Politics of Post-Quantum Bitcoin | NIC CARTER
Isabel Foxen Duke · Nic Carter
Bitcoin Has 3 Years to Survive the Quantum Threat | Nic Carter
Bankless · Nic Carter
Nic Carter: Quantum Threatens $600B of Bitcoin
Delphi Digital · Nic Carter
Nic Carter - Cryptodollarization: The Emerging Markets Story - TOKEN2049 Singapore 2024
TOKEN2049 · Nic Carter
Will Stablecoins Serve or Subvert US Interests
Messari · Nic Carter
Images
Co-investors · 20
Pantera Capital is a blockchain and cryptocurrency-focused investment firm that pioneered early crypto funds in the U.S., offering exposure through venture equity, early-stage tokens, and liquid tokens.
Stillmark is a venture capital firm that invests in companies building products and infrastructure for a bitcoin-powered future.
Acrew Capital is a venture capital firm that emphasizes a team-based approach to investing, offering portfolio companies access to its full team.
Electric Capital is an early-stage venture firm founded in 2018 that backs founders building trust-minimized technologies across AI, crypto, fintech, and related sectors.
Hack VC is a venture capital firm investing in early-stage crypto, blockchain infrastructure, decentralized finance, and AI companies.
Robot Ventures is a $75M early-stage crypto fund founded and led by Robert Leshner (Compound) and Tarun Chitra (Gauntlet), who actively run major DeFi companies while managing the fund, giving founders direct access to operators at the center of on-chain markets. The fund specializes in backing highly technical crypto primitives at the pre-seed stage before they become marquee names, leveraging deep quant research expertise to evaluate complex DeFi mechanisms that many generalist VCs struggle to understand.
Red Swan Ventures backs founders at the earliest stage, aiming to be a founder's first outside capital, focusing on companies born from platform shifts and cultural insight that serve enduring human needs.
M13 is a venture capital firm that invests in seed and Series A stage software companies.
Initialized Capital is a seed-stage venture firm that partners with founders very early — often before product-market fit — providing hands-on support across product, recruiting, go-to-market, PR, and Series A fundraising.
Cyberstarts is a venture firm focused on cybersecurity startups, backing founders who have overcome significant challenges and using a systematic process to identify urgent problems in the sector.
Highland Capital Partners is a venture capital firm with a 39-year history focused on backing entrepreneurs, reporting 200 exits, over 50 IPOs, 40 unicorns, and $7B in assets under management.
Polygon is a blockchain platform positioned as infrastructure for global payments and money movement, enabling assets to move onchain at scale. It offers an open stack for accessing the onchain economy and is powered by its native token $POL.
▶8 more co-investors
The Venture CollectiveSolana VenturesShima CapitalAirTree VenturesChampion Hill VenturesBlockchain Founders FundCadenzaLakehouse Venture Partners
Firms observed investing alongside Castle Island Ventures, from public investor directories. Shared companies are the overlap with Castle Island Ventures's recorded portfolio.
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