COMPANY PROFILE

Castle

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Real-time fraud detection and account takeover prevention

New York City, United StatesFounded 2014Fintech

Valuation $25–50M Last recorded · 2019

Revenue $1–10M Latest reported FY

Headcount <100 Current team size

Total funding $10–50M Disclosed equity funding

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About Castle

Castle is a fraud prevention and account security platform founded in 2015 by Johan Brissmyr (CEO) and Sebastian Wallin (CTO). Originating from the founders' vision as two engineers in Sweden, the company aims to shift the responsibility of security from end-users to online businesses. Castle participated in the Y Combinator Winter 2016 batch and is headquartered in San Francisco.

The company provides a developer-focused infrastructure designed to stop bots, account abuse, and fraud. Castle's business model is delivered as a Software-as-a-Service (SaaS) platform, primarily serving B2B companies that need to secure their web and mobile applications from activities like credential stuffing, fake signups, and transaction fraud. Revenue is generated through a pay-as-you-go subscription model based on API call volume or, for enterprise clients, monthly tracked users (MTU). The company offers a tiered pricing structure, including a free plan for low-volume usage, a pro plan, and a custom enterprise plan.

The platform operates through a dual-layer defense system, combining analysis at the edge with in-app monitoring via an SDK. Key features include advanced device fingerprinting, behavioral analysis, bot detection, AI-powered risk scoring, and email intelligence. This technology allows businesses to distinguish between legitimate users and malicious actors in real-time by analyzing signals such as device integrity, IP reputation, and user behavior patterns. The system enables automated responses, such as blocking or challenging suspicious activities, without negatively impacting the experience for genuine users.

MoreLess Source: Dealroom company data

At a glance

Status: Operational
Founded: 2014
Headquarters: New York City, United States
Employees: 52
Open positions: 6
Dealroom signal: 87.7/100
Industry: Security, Fintech
Sub-industry: Data protection
Sector: Fintech, Risk Management, Analytics, User Behavior, Fraud Detection and Prevention, Cybersecurity, YC W16
Business model: SaaS
Client focus: b2b
Links: Website LinkedIn X

Knowledge graph

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Funding history

7 recorded events

Company financing events and reported valuations.

Deal type	Date	Amount	Valuation	Investors	Source
OtherOther financing	Jan 2021	$0	—	Page One Ventures	↗
SERIES A✓Equity / VC	Feb 2019	$9.2M	$37M	First Round Capital · Y Combinator · Zack Urlocker · F-Prime	↗

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Financials

Revenue over time

Revenue, earnings and other financial measures where available. Years marked “E” are estimates.

Year	Revenue	Growth
2026
2025
2024
2023
2022		—

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Growth signals

Castle website traffic

Latest recorded traffic for Castle is 56K monthly website visits, up 5.7% over the last three months. Castle's team grew 18.2% over the past year.

Latest monthly visits56K 3-month web change+5.7% 1-year team growth+18.2%

Monthly website visitsJan 2016–Jul 2026

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Open positions

Openings linked to this company in Dealroom

Business Operations LeadBrooklyn, NY · Business Development · Jul 18, 2026 Customer Success LeadBrooklyn, NY · CSM & Support · Jun 24, 2026

2 distinct openings shownExplore hiring signals →

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Closest operating peers by Dealroom taxonomy

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