I Reverse-Engineered TikTok’s Algorithm — You Won’t Believe What I Found

Ever wondered why TikTok’s “For You” feed feels like it reads your mind? As a software developer, I couldn’t help but get curious about what’s actually happening under the hood — so I dug into solid sources, read published research, and played around as a user. Here’s what I found, written in plain English, no AI jargon, and every detail grounded in real engineering logic.

The Secret? It’s All in the Signals

What makes TikTok so sticky isn’t magic at all. The secret lies in how well the app pays attention to every tap, swipe, and second you spend in it.

Here’s what TikTok’s system logs:

• How long you watch any video (that’s called “retention”).
• Every like, share, follow — you name it.
• Comments, rewatches, skips.
• What hashtags, music, or captions show up in what you watch.
• Basics like your language or region (but this matters far less than your actual usage).

High-Level Architecture (UML-style Diagram)

Here’s a developer’s-eye view of how it all fits together:

+---------+        +-----------------+…