What does it cost when a fraudulent account slips through your verification? For nearly 60% of banks and fintechs, the answer was over $500,000 in direct fraud losses last year. In fact, online payment fraud exceeded $48 billion globally in 2023.
Verification APIs give businesses a way to authenticate users in seconds, without building and maintaining their own verification infrastructure.
This guide covers how they work, which methods to choose, and what to consider when integrating them.
What Verification APIs Do
Verification APIs are cloud-based interfaces that let businesses authenticate users in real time by integrating verification services directly into applications, websites, and backend systems.
Instead of building OTP delivery, document checks, or biometric verification from scratch, businesses make API calls to send verification requests and receive instant results.
The process is invisible to the end user: they enter a code, tap a button, or do nothing at all (in the case of silent authentication), and the API handles the rest.
This approach replaces what was traditionally a manual, error-prone process. Businesses can verify thousands of users simultaneously while maintaining compliance with Know Your Customer (KYC) and Anti-Money Laundering (AML) regulations.
The global identity verification market is projected to reach $15.78 billion in 2026, growing at 11.18% annually. Demand is driven by the twin pressures of rising fraud and consumer expectations for fast, frictionless onboarding.
Verification Methods Compared
Not all verification methods fit every use case. The right choice depends on the level of security required, the user experience you want to deliver, and the markets you operate in.
| Method | How it works | Security level | User friction | Best for |
| SMS OTP | User receives a code via SMS and enters it to verify. Works on every phone. | Medium – vulnerable to SIM swap and SMS interception | Medium – requires code entry, 15-30 second wait | Account registration, password resets, standard logins |
| WhatsApp / voice OTP | OTP codes delivered via WhatsApp message or automated voice call. | Medium – same code-entry model, but harder to intercept on WhatsApp | Medium – similar to SMS but delivery more reliable in some markets | Fallback when SMS is unreliable; markets where WhatsApp dominates (Indonesia, Malaysia) |
| Silent Mobile Authentication | Background verification using carrier data and device signals. Zero user input. | High – verified at the carrier network level, bypasses SMS entirely | None – verification happens invisibly in under five seconds | Mobile app logins, fintech onboarding, any flow where conversion rate is critical |
| Number lookup | Real-time phone number validation before sending an OTP. Identifies invalid, disconnected, or ported numbers. | Supplementary – not standalone authentication, but flags risk before verification | None – runs before the user sees anything | Pre-verification screening, fraud prevention, reducing wasted OTP spend |
93% of enterprises use SMS OTPs for authentication, making it the most widely deployed method. But deployment doesn’t mean it’s always the right choice. The most effective verification strategies layer these methods. Low-risk actions like password resets might use SMS OTP alone.
High-risk actions like large financial transfers combine OTP with number lookup and device verification. Mobile app logins where every second of friction costs conversions use silent authentication – no code, no wait, no drop-off.
Read More: SMS, WhatsApp, and Viber OTP Authentication: Pros, Cons & Best Practices
The APAC Fraud Challenge
APAC is the fastest-growing region for both digital fraud and identity verification investment.
Identity fraud in the region surged 121% year-over-year in 2024. Deepfake fraud increased 194%, representing 7% of all fraud attempts. Singapore saw fraud rise 207%, Indonesia 205%, and Thailand 201%.
This surge is driven by the region’s rapid fintech expansion and regulatory mandates.
Singapore enforces strict fintech licensing under the Monetary Authority of Singapore (MAS). Digital payment token service providers must implement robust customer due diligence (CDD). Data residency requirements under the PDPA add compliance complexity for verification providers without local infrastructure.
Indonesia’s OJK (Financial Services Authority) regulations require digital identity verification for all financial services. OTP delivery reliability varies significantly across the archipelago’s 17,000+ islands – multi-channel fallback (SMS to WhatsApp to voice) is essential, not optional.
Thailand’s Anti-Money Laundering Office (AMLO) mandates identity verification for financial transactions above threshold amounts. The country’s push toward a digital ID framework is accelerating e-KYC adoption across banking and insurance.
The Philippines’ BSP (Bangko Sentral ng Pilipinas) guidelines require financial institutions to verify customer identity at account opening and for high-value transactions. With Viber as the dominant messaging channel, verification providers need channel coverage beyond SMS and WhatsApp.
For businesses operating across multiple APAC countries, API-based verification offers a critical advantage: consistent security with compliance flexibility. A single API integration can enforce different verification requirements based on the user’s country, adapting to local regulations without building separate verification systems for each market.
Read More: Strong Authentication in Finance: Protecting Customers and Revenue
Integration Considerations for Verification APIs
Integrating a verification API is straightforward, but a few decisions early in the process determine long-term success.
Channel Coverage Across Markets
If your users are in Indonesia, your OTP provider must deliver reliably in Indonesia. If you operate across five APAC markets, you need a provider with consistent delivery across all of them, including fallback options when the primary channel fails.
8×8 maintains direct carrier connections in every APAC market – not aggregator routes – which means higher delivery rates and faster OTP arrival times, especially in markets like Indonesia and the Philippines where aggregator quality varies.
Fallback Logic Between Channels
SMS OTP is the default, but it doesn’t always land. Network congestion, sender ID filtering, and handset issues can delay or block delivery.
A strong API automatically falls back to WhatsApp OTP or voice call when SMS fails, keeping the verification flow intact.
Security Best Practices
All API communication must use HTTPS encryption. API keys need proper storage and rotation.
Rate limiting prevents brute-force attacks on OTP endpoints. Fraud monitoring dashboards track verification patterns and flag anomalies like sudden spikes in failed attempts from a single region.
Webhook and callback handling.
Set up webhooks to receive real-time verification status updates – delivered, read, verified, or expired. This enables your app to update the UI immediately rather than polling, and creates an audit trail for compliance.
Session and expiry management.
OTP codes should expire after 60-90 seconds for security. But short expiry windows combined with slow SMS delivery create user frustration. Build your UI to show a countdown timer, and offer a “Resend” option that triggers the fallback channel rather than resending on the same channel that already failed.
Edge Case Testing
Before going live, simulate edge cases: expired OTPs, network timeouts, invalid numbers, and concurrent verification requests. Also test number porting scenarios (a user who recently switched carriers), dual-SIM devices (which number gets verified?), and international roaming (will the SMS arrive on a foreign network?).
These scenarios reveal integration weaknesses that won’t appear during standard testing.
Read More: Building Safer Digital Journeys with Verification API
How 8×8 Supports Identity Verification
8×8 Verification API provides multi-channel OTP delivery across SMS, WhatsApp, and voice, with automatic fallback logic that routes to the next available channel if the primary fails.
Coverage spans 190+ countries with localized messaging support in 43 languages, critical for businesses operating across APAC markets with diverse language requirements.
For mobile-first markets, 8×8 Silent Mobile Authentication verifies users in the background using carrier data and device signals. No code entry. No user input. Just a verified identity in seconds.
8×8 Number Lookup validates phone numbers before sending OTPs, reducing costs from undeliverable messages and flagging high-risk numbers associated with fraud patterns.
Together with Omni Shield for SMS fraud detection, 8×8 offers a complete verification and fraud prevention stack built on CPaaS infrastructure.
Read More: Guide to verification solutions for businesses of all sizes and types
Choosing the Right Verification Method
The best verification strategy matches the method to the risk level. Not every interaction needs the same level of security, and over-verifying low-risk actions frustrates users.
Standard logins and account registration → SMS OTP. Reliable, universal, requires no app installation, and familiar to users across all demographics. The workhorse of identity verification.
Password resets and account recovery → OTP + Number Lookup. Before sending a reset code, validate that the phone number is still active and hasn’t been recently ported. This catches SIM swap attempts before they succeed.
High-value transactions and sensitive account changes → OTP + Number Lookup + device verification. Layer multiple signals. If the number is valid, the device matches, and the OTP is entered correctly, proceed. If any signal flags, escalate to manual review.
Mobile app authentication where conversion rate matters most → Silent Mobile Authentication. Users don’t enter a code, don’t wait for an SMS, and don’t leave the app. The verification happens in the background in seconds. For fintech onboarding in mobile-first markets like Indonesia and Thailand, this is the difference between a 60% completion rate and a 90% one.
Stronger Verification, Better User Experience
Identity verification doesn’t have to trade security for convenience. The businesses getting this right aren’t choosing between protecting users and keeping them happy – they’re doing both, in seconds, across every market they operate in.
API-based verification gives you the tools to authenticate users instantly, prevent fraud at scale, and maintain compliance across APAC – all without building infrastructure from scratch.
8×8 Verification API delivers OTP across SMS, WhatsApp, and voice in 190+ countries, with silent authentication for frictionless mobile experiences and Number Lookup to catch fraud before it starts.
Talk to 8×8 or discover 8×8 Authentication & Fraud Prevention solutions to explore verification for your platform.
FAQ – Verification APIs
- What is a verification API?
A verification API is a cloud-based interface that lets businesses authenticate user identities in real time by integrating verification services like OTP, silent auth, and number lookup into their applications.
- What is the difference between SMS OTP and Silent Mobile Authentication?
SMS OTP sends a code that users enter manually. Silent authentication verifies users in the background using carrier data, with no user input required.
- How do I choose the right verification method?
Match the method to the risk level. Use SMS OTP for standard logins, OTP plus number lookup for high-value transactions, and silent authentication for frictionless mobile app access.
- Why is APAC a critical market for identity verification?
APAC identity fraud surged 121% in 2024, and the region’s verification market is the fastest-growing globally at 17.1% CAGR. Regulatory mandates across Southeast Asia drive adoption. - What is channel fallback in verification APIs?
Channel fallback automatically routes an OTP to a secondary channel (WhatsApp or voice) if the primary channel (SMS) fails to deliver, ensuring high verification completion rates.
