React Native iOS, in the browser

Pricing

A new React Native iOS simulator.

No Mac, no XCode, no problem.A 100% web-based iOS simulator for React Native.
Makes agents 10x faster and simulators ∞ cheaper.

Download (macOS)

macOS (Intel)Linux (x64)

npm i -g sootsim

Use Cases

Make iOS React Native development as easy as localhost

Point sootsim at any Metro or Vite dev server and your unmodified bundle boots in a browser tab — same hot reload, same gestures, no Xcode in the loop.

+Apple silicon, Intel Mac, Windows, Linux, and headless Chromium all run the same engine in a browser tab.

+Real apps boot today: Bluesky, Uniswap, Expensify, Artsy, Takeout, and 3pc — straight from the demo registry, unpatched.

Hand a teammate or client a URL with a walkthrough of the live app

Instantly record flows into shareable preview links. Both a real bundle and video recording are instantly shareable at a /preview/<id> link.

+People with the link can watch your flow instantly, but also pause and continue the app at any point.

+Entirely client-side — no server bridge causing your demo to feel slow.

Turn every pull request into a tappable preview

A GitHub App runs sootbot in your CI, drives the PR build with a recorded flow, and posts a sticky comment with a video and /preview/<id> link.

+One sticky comment updates as the build progresses — no thread-spam, no broken inline images.

+A failed step keeps the screen, app tree, console, and error payload together, packaged for download.

Run your existing Detox and Maestro flows 100x cheaper

Detox files run unchanged through a Jest preset; bun sootsim maestro plays .maestro/*.yaml against headless Chromium on Linux CI — no Mac runner, no second test stack.

+Existing from 'detox' imports keep working through sootsim/detox/jest-preset — zero test edits.

+Keep the iOS simulator for the final-mile parity check; run the rest of your matrix on Linux for pennies.

Features

Wraps your existing Metro or Vite dev server

A Vite plugin and a Metro plugin attach sootsim without forking your bundler config, or run sootsim open <port> against a live one.

+globalThis.__d and __r are trapped before factories run, so the bundle boots as if it shipped to a real device.

+npm i -g sootsim; the WebSocket bridge auto-starts on port 7668 and the engine shell is served from /__soot/.

Inspect, drive, and record from one CLI

38 top-level verbs talk to the running tab over a WebSocket on port 7668, with per-tab claim leases gating writes.

+tap, type, find, tree, eval, record, flow, screenshot, debug snapshot/diff — every verb is a bridge call.

+flow start / flow keep / flow end records a live session and exports a Maestro-compatible YAML you can replay in CI.

Agents read the canvas as a semantic DOM

A worker-hosted overlay mirrors the render tree into real <button>, <input>, <textarea>, <a>, and <h2> elements with full ARIA.

+aria-label, aria-disabled, aria-checked, aria-busy, aria-expanded, and data-testid come straight off the node.

+Auto-settle extends when the CLI detects an agent env (CLAUDECODE, CODEX_THREAD_ID, CURSOR_TRACE_ID); MCP browser tools query directly.

One render path drives previews, screenshots, and recordings

record, screenshot, and screenshots --plan all capture from the same canvas that runs the live app, inside the tab.

+Recording encodes inside the page — WebM via MediaRecorder, MP4 via VideoEncoder + mp4-muxer, GIF via gifenc. No ffmpeg.

+A YAML plan composes App Store slides; --capture-only and --compose-only split capture from composition for staged CI use.

Engine

A clean-room iOS + RN re-implementation, drawn in Skia

react-reconciler builds the tree, Yoga 3 lays it out, and CanvasKit (Skia compiled to WASM) paints it onto one canvas per surface.

+Three threads: host owns the page, shell worker owns iOS chrome and native UI, tenant worker runs your bundle on OffscreenCanvas.

+Your bundle and pure-JS RN libraries run unmodified; View, Text, ScrollView, gestures, and animation are sootsim's own.

200+ React Native libraries already wired

220+ native modules are stubbed against browser APIs; 350+ pure-JS packages compose sootsim's primitives without a shim.

+Reanimated, Gesture Handler, Screens, FlashList, SVG, MMKV, WebView, Vision Camera, Skia, Notifee — covered.

+@gorhom/bottom-sheet, navigation, gifted-chat, and calendars run as-is — a golden rule of the engine: never re-create pure-JS logic.

iOS chrome and overlays drawn in the same canvas

Status bar, Dynamic Island, keyboard, alerts, action sheets, image picker, notifications, control center, app switcher, home grid, and lock screen all live in the shell worker.

+A seven-stage SkSL liquid-glass shader (SDF → normals → rim → specular → body → rim → composite) drives every glass surface.

+Scroll uses iOS's rubber-band curve 1 − 1/((raw·0.55)/dim + 1); emoji and SF Pro mix through Intl.Segmenter.

A two-runner conformance suite keeps the parity claim honest

Each shared case runs on a real iOS simulator and on sootsim; assertions read layout, focus, scroll state, and event order from both.

+A library-conformance suite covers Reanimated, Gesture Handler, Screens, MaskedView, PagerView, KeyboardController, Drawer, TabView, and ExpoUI.

+Visual proof captures publish per case per device, content-addressed in R2, rendered side-by-side at /proof.

Compatibility

Core

99%

128 pixel-checks

Top 100

88%

88 of 100 native

Top 500

29%

146 of 500 native

top 500 native libraries by weekly downloads

verified

works

partial

not yet

native

all

Essentials(5 of 5)

react-native

the framework itself · 54 pixel-checked surfaces

97%

react-native-gesture-handler

DrawerLayout (passthrough noop), NativeViewGestureHandler still lacks native-scroll coupling and handlerTag semantics, cross-detector simultaneousWithExternalGesture/requireExternalGestureToFail, ForceTouch semantics are placeholder-only

99%

react-native-screens

freezeEnabled/enableFreeze (always false), statusBarStyle/Hidden/navigationBarColor/Hidden ignored, replaceAnimation differentiation, formSheet/pageSheet modal differences, integrated search bar placements

99%

react-native-keyboard-controller

per-frame keyboard progress events (smooth `onMove` requires SAB-backed shared values driven from the shell-side keyboard animation; deferred — see plans/real-worklets.md)

98%

react-native-keyboard-controller sootsim

react-native-reanimated

layout animation builders are exported but no enter/exit animation actually plays, useScrollViewOffset returns static 0, useAnimatedSensor static, useReducedMotion always false, useAnimatedKeyboard height tracking returns 0

98%

All Packages(166 of 202)

1-12 of 166

1 / 14

expo-video

player.duration stays 0 (no timeupdate listener), player.currentTime not synced from element, statusChange/volumeChange/timeUpdate events not emitted, useEvent hook not exported, DRM support absent

100%

react-native-pager-view

overdrag (accepted but ignored), offscreenPageLimit (accepted but ignored), pageMargin, keyboardDismissMode, native scroll fidelity (momentum physics differ)

99%

@mozzius/expo-dynamic-app-icon

noop icon switching — correct for browser, useDynamicAppIcon hook is functional

100%

@react-native-async-storage/async-storage

full localStorage-backed implementation

100%

@react-native-community/checkbox

HTML checkbox input with accentColor tinting

100%

@react-native-community/datetimepicker

HTML date/time/datetime-local input; Android imperative API stubbed

100%

@react-native-masked-view/masked-view

engine-level masked-view node with canvaskit saveLayer + BlendMode.DstIn alpha compositing

100%

@react-native-picker/picker

HTML select element with full Picker API including Picker.Item, modes, focus/blur

100%

@welldone-software/why-did-you-render

intentional noop — wdyr mutates React internals and crashes sootsim's bridged React

100%

expo-glass-effect

liquid glass via CanvasKit _liquidGlass style descriptor; hooks and availability covered

100%

expo-linear-gradient

CanvasKit gradient shader via _gradientColors style prop, full API

100%

expo-sms

SMS not available on web; isAvailableAsync returns false, sendSMSAsync returns cancelled (correct)

100%

1-12 of 166

1 / 14

verified

works

partial

not yet