Castle was founded by Johan Brissmyr, Sebastian Wallin in 2015.

Who are Castle's investors?

Castle's investors include First Round Capital, Index Ventures, Y Combinator, F-Prime Capital, FundersClub, Walking Ventures, Boost VC, Brainchild Holdings and 7 more.

How much funding has Castle raised?

Castle has disclosed $11.7M raised across 1 of its 2 known rounds.

Where is Castle headquartered?

Castle is headquartered in San Francisco, US.

Castle

YC W16

San Francisco, US · Founded 2015 · 20 employees · Hiring · 15 known investors

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Castle builds trust infrastructure for the modern internet, helping organizations detect and prevent fraud and account takeover attacks. The company serves enterprise and mid-market customers requiring security and identity verification solutions.

Also known as Castle Intelligence, Inc. · CASTLE INTELLIGENCE, INC. · Castle Intelligence · Castle.io · Castle.io, Castle, Castle Intelligence

Cybersecurity Developer Tools Enterprise Software SaaS Security Fraud DetectionUnited States of AmericaAmerica / CanadaFully Remote

Founders & leadership· Y Combinator alumni (W16)

Castle was founded in 2015 by Johan Brissmyr and Sebastian Wallin.

Johan BrissmyrCEO & Co-founder

Sebastian Wallin Co-FounderSebastian Wallin is founder and CTO of Castle, which builds fraud detection and account takeover prevention infrastructure for enterprise customers.

Max Nussenbaum FounderVenture Partner at Pioneer

Scott Lowe Founder

Tim Dingman Founder

Board

Shardul Shah Investor at Index Ventures

Investors · 15

First Round Capital✓ confirmed by CastleSan Francisco · $100K – $20M

How we know: the company's own site · firstround.com · Y Combinator's founder network · Not right? Tell us

Index Ventures✓ confirmed by CastleSan Francisco · $540K – $10.8M

How we know: Index Ventures's portfolio page · the company's own site · board seat on SEC Form D · open dataset · 5k.vc investor directory · Y Combinator's founder network · Not right? Tell us

Y Combinator✓ confirmed by CastleSan Francisco · $500K

How we know: the company's own site · the Y Combinator directory · open dataset · 5k.vc investor directory · Not right? Tell us

F-Prime Capitallisted by F-Prime CapitalCambridge · $3M – $10M

How we know: F-Prime Capital's portfolio page · Y Combinator's founder network · Not right? Tell us

FundersClublisted by FundersClubSan Francisco · $290K

How we know: Y Combinator's founder network · Not right? Tell us

Walking Ventureslisted by Walking VenturesLondon · $500K – $1M

How we know: Walking Ventures's portfolio page · Not right? Tell us

Boost VCreportedSan Mateo · $500K

How we know: funding news · Not right? Tell us

Brainchild Holdingsreported

How we know: Y Combinator's founder network · Not right? Tell us

Freestyle CapitalreportedSan Rafael · $3M – $5M

How we know: open dataset · 5k.vc investor directory · Not right? Tell us

Hard YakareportedMuir Beach

How we know: Y Combinator's founder network · Not right? Tell us

HaystackreportedSan Francisco · $1M – $3M

How we know: open dataset · 5k.vc investor directory · Not right? Tell us

Liquid VenturesreportedSan Francisco · $250K – $5M

How we know: Y Combinator's founder network · open dataset · 5k.vc investor directory · Not right? Tell us

Rising TidereportedPacifica

How we know: Y Combinator's founder network · Not right? Tell us

SparkLabs Global VenturesreportedPalo Alto

How we know: the VCSheet dataset · Not right? Tell us

Winklevoss CapitalreportedNew York · $100K – $5M

How we know: funding news · Not right? Tell us

Reported raises · per SEC filings

Form D private placements

$11.7M disclosed across 1 of 2 rounds · 2019–2025

▶$11.7MraisedFeb 2019 · 27 investors · Other Technology

Rule 506(b)

Officers, directors & promoters on the filing

Shardul ShahDirector
Johan BrissmyrExecutive Officer, Director
Sebastian WallinExecutive Officer, Director

Offering amount: $11.7M
Amount sold: $11.7M
First sale: Jan 2019
Incorporated: Corporation, Delaware, 2015
Federal exemptions: 06b

Full filing on SEC EDGAR ↗

Source: SEC EDGAR Form D. Amounts as filed; amended filings shown once at their latest values.

Founder mafia

4 people who came through Castle went on to found or lead other companies.

Henrik TorstenssonInvestorFounded Lifesum Tim DingmanFounderFounded Castle Scott LoweFounderFounded Castle Max NussenbaumFounderFounded Castle

Related companies · 10

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MouseCatMouseCat provides agentic AI infrastructure that automates fraud investigations and risk operations within customer cloud environments. The platform enables enterprises to scale investigation quality across all transactions while retaining full data control and ownership.

Cloudflare, Inc.Cloudflare provides a global cloud network platform delivering security, performance, and development services through sixty-plus integrated services including SASE, application security, and full-stack development infrastructure.

Corgi LabsCorgi Labs builds a platform that uses machine learning to help businesses recover hidden revenue in their payments data through improved fraud detection, transaction approval, and chargeback reduction for online retailers.

FinicFinic provides AI analysis of structured and unstructured data to help fraud detection teams identify organized fraud patterns that traditional rule-based and scoring approaches overlook.

Firefox,Mozilla is a global community organization that develops and maintains open-source internet infrastructure, including the Firefox web browser and Thunderbird email client, while advocating for internet openness, privacy, and user control. The organization also invests in responsible technology startups and creates open-source AI tools for developers.

SlopeSlope provides a B2B payments platform that enables businesses to accept payments and offer financing, with a focus on digitizing the order-to-cash process for online commerce. The company uses generative AI to modernize traditionally manual B2B payment workflows.

NetflixNetflix operates a subscription streaming service for films and television, producing original programming alongside licensed content for members worldwide.

ZenrowsZenRows Extract is a web scraping tool that converts supported websites into typed JSON without requiring custom parsers or CSS selectors, reading a page's DOM to automatically detect and return fields such as prices, ratings, contacts, and listings. It maintains prebuilt extractors for specific sites (e.g. e-commerce, travel, real estate, and professional profiles) and offers a css_extractor option for unsupported pages.

Companies working in the same space as Castle.

Legal entities · 2

corporate structure

Castle Intelligence, Inc.

CASTLE INTELLIGENCE, INC.

Frequently asked questions

What does Castle do?: Castle builds trust infrastructure for the modern internet, helping organizations detect and prevent fraud and account takeover attacks. The company serves enterprise and mid-market customers requiring security and identity verification solutions.
Who founded Castle?: Castle was founded by Johan Brissmyr, Sebastian Wallin in 2015.
Who are Castle's investors?: Castle's investors include First Round Capital, Index Ventures, Y Combinator, F-Prime Capital, FundersClub, Walking Ventures, Boost VC, Brainchild Holdings and 7 more.
How much funding has Castle raised?: Castle has disclosed $11.7M raised across 1 of its 2 known rounds.
Where is Castle headquartered?: Castle is headquartered in San Francisco, US.