Replacement Guide

How to Build Your Own Castle

Replace Castle with a custom build. Stop bots and account abuse in minutes

Few Days
41 features1 integrations3-5 days

Estimated Timeline

Based on 41 features at Few Days difficulty, expect about 3-5 days with AI-assisted development.

1
Architecture & setup
Half day
2
Core features
2-3 days
3
Testing & polish
1 day

Recommended Tech Stack

Next.js 14

Full-stack React framework with API routes and server components

Supabase

PostgreSQL database, auth, and real-time subscriptions

Tailwind CSS

Utility-first styling for rapid UI development

Key Features to Replicate

Top features across 8 categories. See all 41 features

Detection(21 features)

Account Takeover Detection

Identify both bot and human account takeover attacks using scores and heuristics

Behavioral Analysis

Use out-of-the-box signals or create custom aggregations and rate limiters

Bot Behavior Detection

Detect generated emails, abuse IPs, credential stuffing, web crawlers, and automated patterns

Bot Detection

Detect bots, scripts, and coordinated attacks while identifying automated behavior and tampering

Device Fingerprinting

99.5% accurate fingerprinting that uncovers headless browsers, tampering, and carrier data

+16 more in this category

Analytics(4 features)

Network AnalysisPremium

Spot network of bad user activity via shared devices, emails, IPs, payment methods, or addresses

Pattern ExplorationPremium

Uncover bad user activity by querying and visualizing large amounts of data and turn into rules with a few clicks

Session MonitoringPremium

Get a complete history of each user and company down to individual page views and custom actions

User Behavior AnalyticsPremium

Monitor, analyze, and alert on up to 18 months of historical data enriched with user and device intelligence

Integration(3 features)

Cloudflare Integration

Connect Castle to Cloudflare with no code for edge deployment

SDK Integration

Add SDK to track sessions, devices, and behavior enriched with business context for in-app fraud detection

Webhooks

Receive real-time webhooks for fraud events and policy decisions

Scoring(3 features)

Abuse ScoreAI

Risk score indicating likelihood of abusive activity (0-100)

ATO ScoreAI

Account Takeover risk score indicating likelihood of account compromise (0-100)

Bot ScoreAI

Risk score indicating likelihood of bot activity (0-100)

Customization(2 features)

Custom MetricsPremium

Define and track custom metrics for your fraud detection

Custom SignalsPremium

Create custom signals based on your application's specific needs

Policy & Rules(2 features)

Policies

Create and manage security policies for different user actions and risk levels

Rules Engine

Real-time allow, challenge, or deny actions with seamless rule management without code changes

AI & ML(1 features)

AI ScoringAI

Self-learning AI that spots account takeover attempts and abusive behavior

API(1 features)

Real-time API

Query Castle risk data in real-time via API

Cost Calculator

Keep Paying Castle

Monthly$200/mo
Yearly$2.4k/yr
5-Year Total$12k

Build It Yourself

Est. Build Time~5 hrs
Hosting$20/mo
DifficultyEasy

Total Cost Comparison

1 YearSave $2.2k
SaaS
$2.4k
DIY
$240
3 YearsSave $6.5k
SaaS
$7.2k
DIY
$720
5 YearsSave $10.8k
SaaS
$12k
DIY
$1.2k

DIY hosting estimate based on Vercel + Supabase free/pro tiers (~$20/mo). Build time estimated from 41 features at easy complexity.

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