About Renala
Renala is a free macOS disk space analyzer that displays disk usage as an interactive squarified treemap. Select any drive or folder, and Renala scans it in seconds, rendering every file and directory as a proportionally sized rectangle. The treemap uses cushion shading to encode directory depth, so you can spot the largest files at a glance without reading a single label.
The blog
This blog is a 18-article case study documenting how Renala went from zero macOS experience to a published Mac App Store app. It covers the full stack of a native Mac utility: the squarified treemap algorithm, POSIX bulk scanning, Lambert cushion shading, SwiftUI layout and state management, Swift 6 strict concurrency, memory optimization (from 1.2 GB down to 469 MB for million-file volumes), localization across eleven languages, App Sandbox security, and the App Store review process.
Each article focuses on a specific technical decision or obstacle, with code, diagrams, and interactive explainers. No hand-waving, no marketing copy.
Get Renala
Renala is available for free on the Mac App Store. It requires macOS 14 Sonoma or later.
