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📰 Dev.to · SMSRoute Dev

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STOP Is Not a String Match: Building an Opt-Out State Machine That Survives Audits

Dev.to · SMSRoute Dev 📣 Digital Marketing & Growth ⚡ AI Lesson 1mo ago

STOP Is Not a String Match: Building an Opt-Out State Machine That Survives Audits

Keyword matching misses accented replies, multi-word messages, and per-sender scoping. A concrete opt-out data model, the race that re-subscribes users, and wha

Your Inbound SMS Webhook Is a Public Endpoint: HMAC Verification, Replay, and Out-of-Order Delivery

Dev.to · SMSRoute Dev 🔐 Cybersecurity ⚡ AI Lesson 1mo ago

Your Inbound SMS Webhook Is a Public Endpoint: HMAC Verification, Replay, and Out-of-Order Delivery

Anyone can POST to your callback URL. Constant-time HMAC checks, timestamp windows, replay caches, and why status callbacks arrive out of order more often than

Parsing Phone Numbers Is Harder Than Parsing Dates: E.164, libphonenumber, and the Inputs That Break You

Dev.to · SMSRoute Dev 📣 Digital Marketing & Growth ⚡ AI Lesson 1mo ago

Parsing Phone Numbers Is Harder Than Parsing Dates: E.164, libphonenumber, and the Inputs That Break You

Store one canonical E.164 form or your uniqueness constraints and OTP dedupe will silently fail. Parse with region, validate correctly, migrate legacy junk.

Exactly-Once Is a Lie: Building Idempotent SMS Sending with Retries That Don't Double-Text Your Users

Dev.to · SMSRoute Dev 🔧 Backend Engineering ⚡ AI Lesson 1mo ago

Exactly-Once Is a Lie: Building Idempotent SMS Sending with Retries That Don't Double-Text Your Users

Naive SMS retries double-text users on timeouts. Idempotency keys, status-aware retry rules, jittered backoff, and an outbox worker stop duplicate OTPs cold.