If you look at how most cloud IDEs and code sandboxes work today, they almost all share the same underlying architecture: you type code in the browser, it gets sent over a WebSocket to a Node.js or Docker container on a remote server, the server compiles it, and sends the result back. It works, but it introduces a massive bottleneck: Network Latency. Every keystroke is fighting against ping times. If the server is under load, or your Wi-Fi drops for a second, your flow state is completely ruined. While building NitroIDE, I wanted to see if I could bypass the server entirely. I wanted to build an execution engine that responds at the exact speed of thought—0ms latency. Here is exactly how I built a local-first live preview engine entirely in the browser, and how you can do it too. The Secret Weapon: iframe and srcdoc When most developers think of iframes, they think of embedding YouTube videos or loading external URLs via the src attribute.…