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OTP & SMS Security

OTP Expiry and Attempt Limits: Design Guide

Best practices for OTP time windows, max verification attempts, lockout strategies, resend cooldowns, and the UX tradeoffs developers need to consider.

StartMessaging Team·3 Feb 2026·9 min read

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OTP & SMS Security
How to Prevent OTP Fraud and SMS Pumping

Learn what SMS pumping and OTP fraud are, how artificial inflation attacks work, detection signals, prevention techniques, and how to protect your SMS budget.

StartMessaging Team·1 Feb 202610 min read
OTP & SMS Security
SMS OTP vs WhatsApp OTP: Which to Choose?

Compare SMS OTP and WhatsApp OTP for delivery rates, cost, user experience, and reliability in India. Learn when to use each and how to set up fallback strategies.

StartMessaging Team·30 Jan 20268 min read
OTP & SMS Security
How to Rate Limit OTP Requests Properly

Learn proven rate limiting strategies for OTP APIs: per-phone, per-IP, and sliding window approaches to prevent SMS pumping and brute force attacks.

StartMessaging Team·24 Jan 20269 min read
OTP & SMS Security
OTP Security Best Practices for Developers

Learn how to secure OTP systems with bcrypt hashing, rate limiting, expiry windows, attempt limits, HTTPS enforcement, and idempotency keys.

StartMessaging Team·20 Jan 202610 min read

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