MiniSwift — Swift Compiler for the Web

New · Studio IDE

Compiler · SwiftUI · Foundation · Metal — from scratch in C

Swift, compiled<br>in your browser.

A full Swift IDE and the complete SwiftUI runtime — write code, watch it render live. No Apple runtime, no LLVM, no install.

Open Studio<br>See live demos

also new<br>minikotlin.run

miniswift.run/studio

Live SwiftUI preview<br>Console REPL<br>File management<br>Autocomplete<br>⌘K palette<br>Shareable links

Headline · the entire SwiftUI runtime in your tab

SwiftUI, compiled in your browser.

Plain Swift source — including @State, NavigationStack, Toggle, Path, the works. Hit a tab and our in-browser compiler tokenises, parses, type-checks, and lowers to UIIR — then the canvas renderer paints it onto a real iPhone frame. Tap a button → @State mutates → an identity-aware diff engine rebuilds only the affected subtree. No iframe, no JS shim, no native runtime — just Swift → C compiler → WASM → canvas pixels. The same pipeline you'd ship to a phone, running in your tab.

Counter<br>@State · button

Greeting<br>Toggle · ternary

Stack<br>VStack · shapes

Profile<br>composition

Counter.swift<br>edit · live<br>@State · button

swift → lexer → parser → sema → uiir → canvas

Live preview<br>tap the buttons

Our compiler. Our UIIR. Our renderer. Our diff engine. All under one roof in 71K lines of C — no React, no Web Components, no proprietary runtime. The same pipeline you'd target a phone with, just landing on a canvas instead of CoreAnimation.<br>Open in Studio →

Bonus · MSL → WGSL on the side

Metal, too.

Because once you have your own compiler infrastructure, why stop at Swift? libMetal tokenises Apple MSL, lowers to MIR, emits WGSL — WebGPU paints the fragment. Edit the shader, move the mouse, watch it react. Same C-only philosophy: no LLVM, no third-party transpiler.

Tunnel<br>polar coords

Plasma<br>sine fields

Raymarch<br>distance field

Mandelbrot<br>fractal

Metaballs<br>implicit field

Tunnel.metal<br>edit · live<br>polar coords

metal → lexer → parser → mir → wgsl → webgpu

WebGPU canvas<br>atan2 + fract

The 177 KB libMetal WASM tokenises ~106 keywords, lowers to MIR with 90+ builtin rewrites, then emits WGSL plus a JSON pipeline-metadata sidecar — the same library you'd link against in C.<br>Open in Studio →

Plain Swift, Right Here

Edit, hit ▶ Run — compiler runs in your tab.

main.swift

Run

Press Run or Cmd+Enter...

Open MiniSwift Studio for the full editor, live preview and a console.

71K

Lines of C

compiler · stdlib · foundation · swiftui · metal

52

SwiftUI Views

stacks · shapes · paths · canvas · maps

75

Modifiers

layout · style · gestures · sheets · alerts

Dependencies

no npm · no llvm · no clang

Everything You Need to Run Swift

Full Language Support

Structs, classes, enums, protocols, generics, closures, async/await, error handling, pattern matching — all compiled to WebAssembly.

Standard Library

Array, Dictionary, Set, String (Unicode 17.0), Optional, Result, Range — 290 runtime functions with 180+ inlined method handlers.

Foundation

Date / Calendar arithmetic + formatting, URL components & resolution, JSON encode/decode, UUID, UserDefaults, Unicode tables — 70+ runtime functions exposed via a JS bridge.

Metal Shaders

Compile MSL (Metal Shading Language) to WGSL right in the browser. vec3 / mat4 math, mesh primitives (cube · sphere · plane · grid), camera + location passthrough — runs on WebGPU.

WebAssembly Backend

Direct IR-to-WASM compilation. No LLVM, no clang, no Binaryen. Structured control flow, dead code elimination, constant folding.

Plugin Architecture

Modular design: compiler core knows zero about stdlib. Modules register type declarations, IR handlers, and WASM builtins via plugin API.

SwiftUI Runtime ★ headline

The whole declarative UI surface — 52 views, 75 modifiers, sheets, alerts, gestures, Path & Canvas drawing — rendered to canvas via our own UIIR JSON. Identity-aware diff engine surgically rebuilds just the affected subtree on every @State mutation. Same Swift code you'd ship to a phone, no edits.

751 Tests, 100% Pass

Comprehensive test suite covering collections, concurrency, generics, error handling, strings, numerics. Zero regressions policy.

Compiler Pipeline

.swift

Lexer

Parser

Sema

IR Gen

SSA

Optimizer

WASM

.wasm