Developer Guide: Handling M-Pesa STK Push Timeouts and Webhook Validation in Node.js

A technical guide published on DEV Community outlines common failure points when integrating African payment gateways such as M-Pesa, Paystack, and Flutterwave into Node.js backends. The article identifies three key issues: STK Push timeouts caused by late PIN entry or dropped network requests, inconsistent phone number formatting, and unvalidated webhook payloads that expose systems to spoofing. The guide proposes a TypeScript-based solution using a phone number normalizer function to standardize Kenyan phone formats before sending payment requests. It also recommends using the Zod library for strict runtime validation of incoming webhook payloads to prevent malformed or malicious data from reaching the database. Additionally, a background polling function is suggested to reconcile pending transactions when webhook callbacks are never received by the server.