TL;DR: cside vs IPQualityScore
- IPQS does network-level fraud signals well: IP reputation, VPN and proxy detection, email and phone verification. All server-side, so it cannot see inside the browser.
- cside collects from your own first-party JavaScript: fingerprinting at 99.7% accuracy across 250+ signals including IP, geolocation, VPN and proxy, and bot activity, plus in-session behavior, AI agent detection, AI-generated-text detection, and PCI DSS 6.4.3 and 11.6.1 evidence.
- Need IP reputation and email or phone scoring server-side: IPQS. cside covers what it cannot reach: the browser, the session, the payment page.
How cside differentiates its device intelligence
The core difference is machine learning. On top of the 250+ browser, device, and network signals cside collects in each session, it runs separate models for cursor movement, for input and typing patterns, and for broader behavioural signals, then combines their verdicts. Many established tools score a session with one broad, general model. cside reads each behavioural channel with a model built for it.
cside is also specialised rather than generalistic. Instead of one broad platform stretched across every fraud category, it is tuned for specific use cases: account takeover, account sharing, chargeback evidence, and AI agent detection. That focus is what keeps the behavioural models accurate on the attacks that matter to your team.
What is IPQualityScore?
IPQualityScore (IPQS) is a fraud-detection and cybersecurity platform that has operated for over a decade. It is best known for a suite of risk-scoring APIs and a set of free lookup tools. The API suite covers proxy/VPN/Tor and IP reputation, email validation (including disposable-email detection), phone validation, device fingerprinting, and malicious-URL and malware scanning, plus specialised solutions for account takeover, chargeback fraud, and click fraud. According to its own materials, IPQS draws on a proprietary honeypot network, large-scale transaction data across thousands of businesses, botnet monitoring, and dark-web scanning to produce risk scores and reputation data.
IPQS publishes plan pricing and offers a free plan (1,000 lookups per month at the time of writing) plus self-serve paid tiers, with an Enterprise tier, which unlocks features such as device fingerprinting, available through sales. It states that data shared with its API endpoints is processed under ISO 27001 and SOC 2 Type II standards and that it is GDPR- and CCPA-compliant.
How IPQualityScore works
IPQS is primarily an API-and-score model. Your systems call IPQS endpoints, or embed its JavaScript device tracker and mobile SDKs, and IPQS returns risk scores and reputation data (for example, fraud scores, proxy/VPN flags, and device-fingerprint risk across what it describes as 300+ data points). Your application then decides what to do with those scores.
Two things follow from that design that matter for a client-side security buyer. First, the device fingerprint tracker is a JavaScript that, by default, loads from an IPQS-owned domain (www.ipqscdn.com or ipqualityscore.com), a third-party origin that privacy extensions can target. IPQS does document a custom-domain option that lets you serve the tracking script from a domain you register, which reduces that exposure if you configure it. Second, that tracker is itself a third-party script running on your pages, precisely what PCI DSS 6.4.3 asks merchants to inventory and monitor, and IPQS's public materials don't describe a product for inventorying or tamper-monitoring the scripts on your payment pages.
How cside fits
cside isn't a replacement for the broad fraud-scoring suite IPQS offers, IP, email, phone, and URL scoring are jobs IPQS does and cside doesn't, and we won't pretend otherwise. What cside does is the layer underneath and around the device-signal and script story.
On the layer the two share, device, bot, and AI-agent detection, cside collects device and behavioral signals from your own first-party JavaScript, so there's no fixed third-party origin for a filter list to block and no fixed collector for a fraudster to detect and feed. It reads in-session behavior on the live page, mouse-movement patterns, scroll behavior, and typing cadence, alongside device fingerprinting (cside cites 99.7% accuracy across 250+ signals including IP, geolocation, VPN/proxy, and bot activity), with integrated bot and AI agent detection. It also adds a signal IPQS doesn't offer: an AI-generated-text detection engine, pass the contents of a form field (a review, a signup bio, a support message) and cside tells you whether a human or an AI wrote it. There's more on our bot detection and AI agent detection pages, and Avneh's posts on behavioral cursor detection and the two-stage neural detection stack explain the underlying motion and session signals in more detail.
Beyond bot detection, cside does the thing IPQS doesn't market: it inventories, justifies, and tamper-monitors every script on your payment pages, including device trackers like the IPQS one, to automate PCI DSS 4.0.1 requirements 6.4.3 and 11.6.1, with QSA-ready reports (VikingCloud-validated and accepted by leading QSAs). It gives you evidence you own, usable in chargeback disputes through our Chargebacks911 integration, deploys via a single first-party script tag, no proxy, no DNS changes, for 100% session visibility at zero added latency, and is SOC 2 Type II, ISO 27001, and GDPR-compliant with a 99.9% uptime SLA and 50+ integrations. Many teams run a fraud-scoring API like IPQS and cside together; if the first-party device-signal layer or PCI script coverage is your gap, that's where cside fits.
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Related resources
Founder and CEO of cside. Previously a product manager on Cloudflare Page Shield (now Cloudflare Client-Side Security). Co-chair of the W3C Anti-Fraud Community Group and a Forbes 30 Under 30 honoree. Building accessible security against client-side attacks, web security is not an enterprise-only problem.
