Bonsplit: Tabs and window splits manager for native macOS applications

What it does

Bonsplit is a macOS library for SwiftUI developers that adds tabbed interfaces and split pane layouts to native applications. Developers can create tabs with icons and dirty indicators, split panes horizontally or vertically, update tab properties dynamically, and navigate between panes using directional commands. The library includes 120fps animations, drag-and-drop tab reordering, and keyboard navigation.

Who it is for

This is a developer tool for macOS app creators building in SwiftUI. It targets engineers who need multi-pane layouts similar to IDEs, text editors, or document viewers. The target audience wants a pre-built solution rather than coding tabbed interfaces from scratch.

Pricing

The site does not show prices.

How it stands out

Bonsplit is open source on GitHub. The library emphasizes smooth 120fps animations and provides two-way geometry synchronization with external programs. It includes built-in support for tab reordering via drag-and-drop and keyboard-driven pane navigation in four directions. The API appears designed for fine-grained control: developers can target specific panes, create tabs with optional metadata, and observe state changes.

What a founder should check

First, assess the competitive landscape. Other SwiftUI UI libraries and macOS frameworks already handle tabs and splits. Examine whether existing solutions from major frameworks or indie developers already solve this problem well enough that adoption friction is low.

Second, verify switching costs and distribution. Since this is open source, understand how many developers are actively using it, what the maintenance burden looks like, and whether being free creates challenges for monetization if the goal is to build a business around it.

Third, evaluate the moat. A tabbing library has limited defensibility unless paired with a larger platform or ecosystem. Check whether competitors can quickly replicate the 120fps animations, drag-and-drop, and geometry sync features, and how much of the value depends on proprietary implementation versus standard macOS capabilities.

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