https://signops.dev/blog/Push notifications, OTP and passkeys for developers https://signops.dev/blog/fcm-http-v1-migration/https://signops.dev/blog/fcm-http-v1-migration/Mon, 19 Oct 2026 00:00:00 GMTThe FCM legacy API is shut down. How to move to HTTP v1: service account tokens, the new payload, sending to many tokens, and Node, PHP and cURL examples. https://signops.dev/blog/fcm-notification-not-received/https://signops.dev/blog/fcm-notification-not-received/Mon, 19 Oct 2026 00:00:00 GMTWhy Android does not show FCM notifications when the app is closed or killed: message types, priority, Doze, permissions, stale tokens and OEM battery savers. https://signops.dev/blog/push-notifications-xiaomi-oppo-vivo/https://signops.dev/blog/push-notifications-xiaomi-oppo-vivo/Mon, 19 Oct 2026 00:00:00 GMTBattery savers on Xiaomi, Redmi, Poco, Oppo, Realme, Vivo and OnePlus stop apps and drop pushes. What developers can change in the app and what users must switch on. https://signops.dev/blog/firebase-push-notification-pricing/https://signops.dev/blog/firebase-push-notification-pricing/Mon, 19 Oct 2026 00:00:00 GMTFirebase Cloud Messaging is free on every plan. What the limits are, what is not free around it, and what a push backend costs to run. https://signops.dev/blog/send-push-notification-node-js/https://signops.dev/blog/send-push-notification-node-js/Mon, 19 Oct 2026 00:00:00 GMTSend FCM push notifications from Node.js: firebase-admin setup, one user, many tokens, topics, all users, scheduling and cleaning up dead tokens. https://signops.dev/blog/expo-push-notifications-not-working/https://signops.dev/blog/expo-push-notifications-not-working/Mon, 19 Oct 2026 00:00:00 GMTThe common reasons Expo push notifications stop in production builds: FCM v1 credentials, google-services.json, Expo Go limits, receipts and Android channels. https://signops.dev/blog/sms-otp-cost-india/https://signops.dev/blog/sms-otp-cost-india/Mon, 19 Oct 2026 00:00:00 GMTSMS OTP prices in India per message, what DLT registration involves for OTP templates, whether you can send OTP without DLT, and the cheaper options. https://signops.dev/blog/supabase-email-rate-limit/https://signops.dev/blog/supabase-email-rate-limit/Mon, 19 Oct 2026 00:00:00 GMTSupabase's built-in email sender is for testing and allows only a few emails an hour. How custom SMTP raises the limit, and other ways to send sign-in codes. https://signops.dev/blog/better-auth-email-otp/https://signops.dev/blog/better-auth-email-otp/Mon, 19 Oct 2026 00:00:00 GMTSet up the Better Auth email OTP plugin, choose a sender for the codes, and handle expiry, tries and rate limits in production. https://signops.dev/blog/firebase-auth-email-otp/https://signops.dev/blog/firebase-auth-email-otp/Mon, 19 Oct 2026 00:00:00 GMTFirebase Auth offers email links, not 6-digit email codes. How to build email OTP sign-in with a Cloud Function and a custom token. https://signops.dev/blog/email-otp-vs-sms-otp/https://signops.dev/blog/email-otp-vs-sms-otp/Mon, 19 Oct 2026 00:00:00 GMTEmail OTP and SMS OTP compared on price in India, DLT, delivery, SIM swap and phishing risk, with when to use each. https://signops.dev/blog/passkeys-vs-otp/https://signops.dev/blog/passkeys-vs-otp/Mon, 19 Oct 2026 00:00:00 GMTHow passkeys work, why they cannot be phished like an OTP, which devices support them, and how to add them next to the login you already have. https://signops.dev/blog/push-authentication-number-matching/https://signops.dev/blog/push-authentication-number-matching/Mon, 19 Oct 2026 00:00:00 GMTWhat push authentication is, how MFA fatigue attacks beat it, why number matching stops them, and how it compares with an OTP. https://signops.dev/blog/rbi-authentication-directions-2025/https://signops.dev/blog/rbi-authentication-directions-2025/Mon, 19 Oct 2026 00:00:00 GMTWhat the RBI's Authentication Mechanisms for Digital Payment Transactions Directions, 2025 ask of apps from 1 April 2026, and the alternatives to SMS OTP they name.