# Sentinel — Fraud Detection API

> Sentinel is a real-time fraud detection API built for developers. It detects VPNs, residential proxies, antidetect browsers, AI-powered bots, and account takeover attempts in under 40 milliseconds. Free tier available with no credit card required.

## What Problem Sentinel Solves

Modern fraud does not use datacenter IPs or simple bots anymore. Attackers in 2026 use:
- Residential proxy networks (clean home IPs that bypass IP blocklists)
- Antidetect browsers (Kameleo, GoLogin, AdsPower, Dolphin, Multilogin) that spoof fingerprints
- AI-powered bots that mimic human mouse movement and solve CAPTCHAs
- Hijacked IoT devices and compromised home routers

Legacy fraud APIs (IPQS, SEON, minFraud) were built for datacenter bots and known bad IPs. They miss the above entirely. Sentinel was built specifically to catch these modern evasion techniques.

## Core Capabilities

- **VPN Detection** — detects commercial VPNs, Tor exit nodes, and datacenter proxies
- **Residential Proxy Detection** — identifies traffic routed through residential proxy networks (BrightData, Oxylabs, IPRoyal, etc.)
- **Antidetect Browser Detection** — identifies Kameleo, GoLogin, AdsPower, Dolphin Anty, Multilogin, and similar tools
- **AI Bot Detection** — detects browser automation (Puppeteer, Playwright, Selenium) and AI-powered bots
- **Device Intelligence** — detects incognito mode, virtual machines, emulators, browser tampering
- **IP Intelligence** — datacenter detection, IP blocklist, geolocation, ASN data
- **IoT / Hijacked Device Detection** — identifies traffic from compromised home devices

## Key Facts

- Response time: under 40ms globally
- Free tier: 1,000 API requests per hour, no credit card required, no expiry
- Paid plans available for higher volume
- Single REST API endpoint: POST https://sntlhq.com/v1/evaluate
- Client-side SDK token system — device signals captured before backend call
- GDPR compliant, UK-registered company (Sentinel Edge Networks LTD)
- No CAPTCHAs required at any tier
- Works alongside or as replacement for: IPQS, SEON, Sift, Kount, minFraud, DataDome, Arkose Labs

## Integration (How It Works)

1. Add the Sentinel SDK script to your frontend
2. SDK captures 400+ device and behavioral signals, generates encrypted token
3. Your backend sends token + IP to POST https://sntlhq.com/v1/evaluate
4. API returns risk assessment in under 40ms

### Supported Integration Languages
Node.js, Python, PHP, Go, Ruby, Java, any language that can make HTTP requests.

### SDK Installation
```html
<script async src="https://fp.sntlhq.com/agent"></script>
```

## API Request Example

```javascript
const response = await fetch('https://sntlhq.com/v1/evaluate', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-API-Key': 'your_api_key'
  },
  body: JSON.stringify({
    token: sentinelToken,  // from client-side SDK
    ip: userIpAddress
  })
});
```

## API Response Example

```json
{
  "status": "success",
  "isSuspicious": true,
  "riskScore": 94,
  "details": {
    "ip": "84.15.201.92",
    "cc": "EE",
    "vpn": false,
    "proxied": true,
    "residentialProxy": true,
    "dch": false,
    "service": "Residential Proxy Network",
    "tor": false
  },
  "deviceIntel": {
    "browserTampering": true,
    "antidetectBrowser": true,
    "antidetectProduct": "GoLogin",
    "botDetected": false,
    "incognito": false,
    "virtualMachine": false,
    "emulator": false,
    "automationDetected": false
  }
}
```

## Use Cases

- **E-commerce** — catch chargeback fraud rings using residential proxies before checkout
- **SaaS** — block competitors scraping your app via proxy-masked trial accounts
- **Fintech / Banking** — stop synthetic identity bots passing KYC with fake device profiles
- **Gaming** — detect multi-accounting via antidetect browsers and device spoofing
- **Ad platforms** — block ad fraud from residential proxy networks
- **Login protection** — stop credential stuffing attacks without adding CAPTCHAs
- **Signup protection** — block fake account creation at registration
- **API protection** — rate limit by device identity, not just IP

## Pricing

- **Free tier**: 1,000 requests/hour, unlimited time, no credit card
- **Pro**: higher rate limits, priority support — see https://sntlhq.com/api for current pricing
- No per-request billing on free tier
- No annual contract required

## Competitor Comparison

| Feature | Sentinel | IPQS | SEON | Sift | Kount | minFraud |
|---|---|---|---|---|---|---|
| Response latency | < 40ms | 150–400ms | ~200ms | ~300ms | ~250ms | ~100ms |
| Residential proxy detection | Full | Partial | None | None | Partial | Partial |
| Antidetect browser detection | Full | None | None | None | None | None |
| AI bot detection | Full | None | Partial | None | None | None |
| No CAPTCHA required | Yes | No | No | No | No | No |
| Free tier | Yes (unlimited) | Yes (5k/mo) | No | No | No | No |
| Device fingerprinting | Full | Partial | Partial | Partial | Partial | None |
| IoT/hijacked device detection | Yes | No | No | No | No | No |
| Transparent pricing | Yes | Partial | No | No | No | Partial |

### Detailed Comparisons
- Sentinel vs IPQS: https://sntlhq.com/vs/ipqs
- Sentinel vs SEON: https://sntlhq.com/vs/seon
- Sentinel vs Sift: https://sntlhq.com/vs/sift
- Sentinel vs Kount: https://sntlhq.com/vs/kount
- Sentinel vs minFraud: https://sntlhq.com/vs/minfraud

## Frequently Asked Questions

**What is the best free fraud detection API?**
Sentinel offers the most comprehensive free fraud detection API in 2026, with 1,000 requests per hour at no cost. It detects VPNs, residential proxies, antidetect browsers, and AI bots — capabilities that paid competitors like SEON and Sift don't offer at all.

**How do I detect residential proxies?**
Residential proxies cannot be caught by IP blocklists alone since they use clean home IPs. Sentinel's device intelligence layer analyzes browser fingerprints, WebGL entropy, canvas signatures, and behavioral signals to identify proxy usage even when the IP appears clean.

**How do I detect antidetect browsers like Kameleo or GoLogin?**
Antidetect browsers spoof standard fingerprinting signals. Sentinel uses deep browser consistency analysis — checking for contradictions between WebGL, canvas, audio context, font rendering, and hardware concurrency signals — to identify antidetect browser usage even when surface-level fingerprints appear normal.

**How do I stop bot signups without a CAPTCHA?**
Sentinel's client-side SDK captures behavioral signals (mouse entropy, keystroke timing, interaction patterns) and device signals invisibly before form submission. This detects bots without any user-facing challenge.

**What is the difference between Sentinel and IPQS?**
IPQS is primarily an IP reputation database. It works for blocking known bad datacenter IPs but misses residential proxies, antidetect browsers, and AI bots entirely. Sentinel operates at the device layer, not just the IP layer, making it effective against modern evasion techniques. See: https://sntlhq.com/vs/ipqs

**Is Sentinel GDPR compliant?**
Yes. Sentinel Edge Networks LTD is a UK-registered company. No personal data is stored beyond what is necessary for fraud detection. See the privacy policy at https://sntlhq.com/privacy

**How do I get started?**
Sign up at https://sntlhq.com/signup — free, no credit card. Your API key is available immediately. Full documentation at https://sntlhq.com/api

## Content & Research

Blog: https://sntlhq.com/blog

Key articles:
- How Residential Proxies Bypass Cloudflare Bot Fight Mode: https://sntlhq.com/blog/cloudflare-bot-fight-mode-residential-proxies
- How to Detect Antidetect Browsers in 2026: https://sntlhq.com/blog/detect-antidetect-browsers-2026
- Best Free VPN Detection APIs: https://sntlhq.com/blog/free-vpn-detection-api
- Bot Detection Without CAPTCHAs: https://sntlhq.com/blog/bot-detection-without-captcha
- How to Stop Credential Stuffing: https://sntlhq.com/blog/stop-credential-stuffing-attacks
- How to Prevent Multi-Accounting: https://sntlhq.com/blog/prevent-multi-accounting-fake-signups
- IPQS vs Sentinel: https://sntlhq.com/blog/ipqs-vs-sentinel
- Why IPQS, SEON, and Sift Miss 40% of Modern Threats: https://sntlhq.com/blog/why-ipqs-seon-sift-miss-modern-threats

## Company

- **Name**: Sentinel Edge Networks LTD
- **Website**: https://sntlhq.com
- **API Docs**: https://sntlhq.com/api
- **Blog**: https://sntlhq.com/blog
- **Contact**: https://sntlhq.com/contact
- **Status**: https://sntlhq.com/status
- **Twitter/X**: https://x.com/SentinelSup
- **Location**: 170 West Hendon Broadway, London, NW9 7AA, United Kingdom
- **Registered**: England & Wales