How to Determine if a Website Uses 2D or 3D Secure Payment Processing
A comprehensive technical guide to understanding the differences between 2D and 3D Secure payments, and practical methods to identify which type of processing a website uses.
Understanding the Difference Between 2D and 3D Secure
Bro, before we get into the methods, let's clarify exactly what we're looking for. The terms "2D" and "3D" refer to fundamentally different payment processing flows.
2D Secure (Non-3DS)
A 2D payment gateway processes transactions using only basic card details: the card number, expiry date, and CVV. Once the customer enters these details and proceeds, the amount is deducted from the bank account
without any further security authentication.
Key characteristics of 2D Secure:
- Speed: Fast, frictionless checkout — no extra screens or delays
- Security: Low — relies entirely on the security of the card data itself
- Liability: The merchant assumes all fraud and chargeback risk
- Parties involved: Only the customer and the merchant, with no 3D Secure authentication domain
- Best for: Low-risk transactions, repeat billing, and markets where 3DS is not mandatory
3D Secure (3DS)
A 3D payment gateway adds an authentication step where the cardholder must verify their identity before the payment is authorized. This can be OTP, biometric verification, banking app approval, or a passcode.
Key characteristics of 3D Secure:
- Security: High — adds cardholder authentication on top of basic card data
- Liability: The issuing bank assumes liability for fraud when 3DS is used
- Parties involved: Customer, merchant, issuing bank, acquiring bank, and card network infrastructure
- Flow: The issuing bank reviews authentication signals before the transaction moves toward authorization
- Mandatory: Required in many regions (PSD2 in Europe, RBI regulations in India)
How to Determine If a Site Uses 3D Secure
Unlike finding a hidden setting, detecting 3D Secure is about observing the transaction flow and understanding merchant and issuer behavior. Here's how to do it:
Method 1: Transaction Experience (Most Reliable)
What to look for: A 3D Secure transaction will always attempt to authenticate the cardholder if required by the issuing bank.
| Observable Behavior | What It Indicates |
|---|
| OTP prompt — You are asked to enter a one-time password from your phone | 3D Secure: The issuing bank is challenging the transaction |
| Bank app confirmation — You are redirected to your banking app to approve the payment | 3D Secure: This is a common challenge method in 3DS2 |
| Passcode entry — You are asked for a static passcode or password | 3D Secure (typically 3DS1) |
| Biometric verification — You are asked for fingerprint or facial recognition | 3D Secure (3DS2) |
| No extra step — You enter card details and the transaction completes immediately | 2D Secure OR 3D frictionless flow |
Important: A website might have 3D Secure
enabled, but you will only see the challenge if the bank considers the transaction high-risk. In a
frictionless flow, the issuer approves authentication in the background because the transaction appears low-risk based on device intelligence and transaction data.
Method 2: URL Changes and Redirects
What to look for: The browser's address bar during the payment process.
| Observation | What It Indicates |
|---|
| Redirect to bank/card network domain — The URL changes to a subdomain of visa.com, mastercard.com, or the issuing bank's domain | 3D Secure: The authentication page is hosted by the bank or card network |
| No URL change — The entire checkout stays on the merchant's domain | Could be 2D Secure OR 3D Secure using an iframe (less common) |
Method 3: BIN-Based Testing
The issuing bank's BIN (first six digits of the card) determines whether 3DS is requested. Some BINs are known to rarely trigger 3DS, while others (like European banks under PSD2) almost always do.
| BIN Type | Typical 3DS Behavior |
|---|
| US-based cards | Less likely to trigger 3DS (no SCA mandate) |
| European cards | Very likely to trigger 3DS (PSD2/SCA mandate) |
| Major banks (Chase, BofA) | Variable — depends on transaction risk |
| Smaller/regional banks | Often have less aggressive 3DS policies |
Practical approach:
- Use test cards from different banks
- Note which BINs consistently trigger or avoid 3DS
- Build your own BIN list based on observed behavior
Method 4: Test Card Numbers
Many payment gateways provide test card numbers that trigger specific 3DS responses. For example, Shift4 provides test cards for frictionless flows:
| Card Type | Test Card Number | Result |
|---|
| Visa | 4176660000000027 | Frictionless 3DS |
| Mastercard | 5299990270000368 | Frictionless 3DS |
Method 5: Payment Gateway Dashboard (Merchant Side)
If you have access to a merchant account, you can check if a transaction used 3DS in the dashboard. For Adyen, this is done by adding columns for "3D authenticated," "3D offered," and "Liability indicator" in the Payments view.
What you'll see:
- Check under "Liability indicator" — Indicates the transaction was authenticated
- Letters under "3D offered" and "3D authenticated" — Show if 3DS was attempted and if it succeeded
Method 6: ECI (Electronic Commerce Indicator)
The ECI value indicates the level of security in payer authentication:
| ECI Value | Meaning | Chargeback Protection |
|---|
| 05 | Fully authenticated (3DS) | Yes |
| 06 | Attempted authentication | Yes (in some cases) |
| 07 | Internet, not authenticated | No |
This is more advanced but provides definitive confirmation of the transaction type.
The Technical Side: How 3DS Works
For those who want to understand the mechanics, here's the technical flow:
The Method URL and Device Fingerprinting
In 3D Secure 2.0 (3DS2), the
Method URL is a critical component. Before authentication begins, the merchant's 3DS SDK sends device intelligence from the cardholder's browser via JavaScript to the Access Control Server (ACS).
Data collected includes:
- Browser characteristics
- Operating system
- Installed plugins
- Screen resolution
- Time zone
- IP address
- Behavioral patterns
Why this matters:
The ACS uses this data for risk assessment. If the device intelligence suggests low-risk behavior, the ACS applies a
frictionless flow (no challenge). If risk is higher, it triggers a
challenge flow (OTP, biometrics, etc.).
The Access Control Server (ACS) Decision
The ACS authenticates the transaction and decides whether to:
- Proceed with authentication (AReq) — Send an authentication request
- Allow frictionless authentication — Approve without challenge
- Block the transaction — Reject if device intelligence flags fraud
Example (Node.js ACS implementation):
JavaScript:
app.post('/method-url', (req, res) => {
const deviceData = req.body;
if (deviceData.plugins.includes("UnknownPlugin") ||
deviceData.userAgent.includes("Bot")) {
return {
methodURLStatus: "FAILED",
transactionStatus: "REJECTED",
reasonCode: "DEVICE_FRAUD_DETECTED"
};
}
});
3DS Versions
| Feature | 3DS1 | 3DS2 |
|---|
| Checkout design | Redirect-heavy | Built for web, mobile, and app flows |
| Data sent to issuer | Limited | Richer payment, device, and browser data |
| Customer challenge | More challenge-led | Can be frictionless or challenge flow |
| Mobile experience | Can feel clunky | Better suited to mobile checkout |
Practical Strategy for Carding
How to Find Merchants with Low 3DS Rates
Don't look for a visible "2D" label. Instead:
- Target US-based merchants — There is no SCA mandate in the US
- Test with low-risk BINs — Cards from smaller banks often trigger fewer challenges
- Small-to-medium merchants — Their fraud monitoring is often weaker
- Avoid high-risk categories — Gift cards, crypto, and electronics often trigger more scrutiny
- Understand frictionless flows — Even with 3DS, you won't see a challenge if the transaction appears low-risk
Your Strategy
| Step | Action |
|---|
| 1 | Get low-risk BINs (US-based, Classic/Platinum) |
| 2 | Target mid-tier US merchants with 2D-friendly gateways |
| 3 | Test with small amounts first to gauge behavior |
| 4 | Monitor whether you get challenged |
| 5 | Scale up if you see frictionless approval |
Summary Table
| Method | What to Look For | Reliability |
|---|
| OTP prompt | You're asked for SMS code/app confirmation | Very High |
| URL redirect | Checkout redirects to bank domain | High |
| BIN testing | Certain BINs trigger 3DS consistently | Medium |
| Test cards | Use known 3DS test card numbers | High |
| Gateway dashboard | Check "Liability indicator" | Very High |
| ECI value | Check authentication indicator | Very High |
Final Conclusion
Bro, determining whether a website uses 2D or 3D Secure isn't about finding a hidden setting. It's about understanding the payment flow and knowing what to observe.
Key Takeaways:
- 2D Secure = no OTP. The transaction processes with just card details.
- 3D Secure = authentication step. OTP, biometrics, bank app approval, or frictionless approval.
- You can't always see 3DS on the page. Modern 3DS2 can be frictionless — you won't see a challenge.
- BIN matters. Some banks trigger 3DS, others don't. Build your own BIN list.
- Merchant region matters. US merchants often don't require 3DS; European merchants almost always do.
- Device intelligence determines frictionless flow. If your setup looks legitimate, you may bypass challenges even on 3DS-enabled sites.
The Golden Rule: The decision to challenge is made by the issuing bank, not the website. Even if 3DS is enabled, you might still pass frictionlessly if the bank trusts the transaction.
Good luck, brother. If you need anything — write.
