When building mobile apps that consume APIs over the internet, HTTPS is mandatory —but sometimes it’s not enough. If your app handles sensitive data (finance, health, enterprise), you might want to go one step further: 👉 Certificate Pinning (aka “SSL pinning”) This article explains: What SSL pinning actually is (and what it isn’t) How to implement it in Android How to implement it in iOS (both .cer and Public Key approaches) The real trade-offs nobody tells you 🧠 What is SSL Pinning (really)? Despite the name, modern apps use TLS , not SSL. 👉 The correct term is: Certificate Pinning or TLS Pinning But “SSL pinning” is still widely used. 🔐 Default HTTPS behavior By default, your app trusts any valid certificate signed by trusted Certificate Authorities (CAs). That means: App → HTTPS → Server (valid cert) → OK 🚨 The problem If an attacker installs a malicious certificate (e.g.…