GitHub - jo-duchan/tapflow: Self-hosted iOS & Android simulator streaming for the whole team

A self-hosted Appetize / BrowserStack alternative for mobile QA teams Run iOS simulators and Android emulators in any browser — no toolchain setup, no device pool, no cloud uploads. Your builds, streams, and recordings stay on infrastructure you control. 📖 Docs  ·  🚀 Quick Start  ·  🎥 Demo  ·  🎬 Setup

new-demo.mp4

v0.x: tapflow is under active development. Breaking changes may appear in minor versions until v1.0.0. See ROADMAP for the full plan.

Why tapflow? Mobile QA usually depends on access to simulators, emulators, or physical devices — and that access is uneven across a team. For mobile developers it means opening Xcode or Android Studio on a Mac. For everyone else, it often means asking a mobile developer every single time:

Backend developer — "How do I install the sandbox build to check what was deployed?" Product manager — "I keep installing and removing versions just to compare behavior." Designer — "I need to check the layout across screen sizes, but I don't have the right devices."

Physical devices add their own overhead — OS-version coverage, availability, charging, storage, handoff. Cloud simulator services solve access, but they require uploading internal builds to a third-party service and paying for remote devices while your own Macs can already run the same simulators. We hit this exact problem, so we built tapflow.

Solution The catch

Appetize / BrowserStack Recurring cost — and app builds are uploaded to a third-party cloud

Physical devices Cost, availability, OS coverage, management overhead

Xcode / Android Studio Each teammate needs a Mac and a full mobile toolchain

tapflow Reuse your own Macs — data stays on infrastructure you control, and the whole team does QA from a browser

What tapflow does tapflow connects three parts:

A self-hosted relay server (Linux or Mac) A macOS agent that drives iOS simulators and Android emulators A browser dashboard for the rest of the team

The agent connects outbound to the relay. Teammates open the dashboard, pick an available device, and interact with it remotely — while the simulators and emulators keep running on your own Macs. What tapflow is not tapflow doesn't replace native mobile development tools. Mobile developers still use Xcode, Android Studio, and their build tooling. tapflow makes the running simulators and emulators accessible to the rest of the team through a browser — it isn't an automation framework or a device farm. How it works Browser (your team) ←─ WebSocket ─→ Relay Server ←─ WebSocket (outbound) ─→ Mac Agent (Linux / Mac) (iOS · Android)

The Mac Agent connects outbound to the relay — no inbound firewall rules needed. Anyone on the team opens the dashboard in any browser and sees all available devices. Touch events are forwarded in real time; the screen streams back to the browser. The relay also serves the dashboard SPA on the same port — no separate web server needed.

Quick Start 1. Install npm install -g tapflow # or: yarn global add tapflow | pnpm add -g tapflow 2. Set up the environment On the Mac that will run an agent, install the simulator/emulator prerequisites in one step: tapflow setup Skip this on a relay-only server (Linux). See Environment Setup for details. 3. Start relay + agent tapflow start # ✓ Relay started on http://localhost:4000 # ✓ iOS Agent connected (3 simulators available) This starts both the relay and the agent on the same Mac (local mode).

4. Create the first admin account Open http://localhost:4000 in your browser. tapflow redirects you to /setup to create the admin account.

Headless server? Use tapflow admin init to create the admin account via CLI instead.

5. Open the dashboard Navigate to http://localhost:4000 and sign in with the account you just created.

Having issues? Run tapflow doctor to re-check prerequisites at any time.

Requirements

Component Requirements

Relay server Node.js ≥ 20, any OS (Linux/macOS), ~512 MB RAM

iOS Agent macOS, Xcode + iOS Simulator runtime (or run tapflow setup ios), Node.js ≥ 20

Android Agent macOS, Java + Android SDK with an AVD (or run tapflow setup android), Node.js ≥ 20

Browser (QA) Any modern browser — Chrome, Firefox, Safari, Edge

Agents run on macOS only (they drive the iOS Simulator and Android emulator on a Mac). The relay runs anywhere.

Features

No mobile toolchain for QA users — teammates test from a browser without installing Xcode, Android Studio, or local simulator tooling. Self-hosted by default — app builds, device streams, recordings, and account data stay on infrastructure you control. Use your existing Mac setup — run agents on Macs that already have the iOS Simulator or Android emulator available. API-first — REST endpoints and Personal Access Tokens support CI/CD and AI-agent workflows.

What's included:

Browser streaming — iOS & Android at ~30 fps, no extra app on the device. Both stream H.264 through a 2-tier decoder (WebCodecs on secure contexts, WASM/tinyh264 on plain HTTP), which removes the media-element buffer from the decode path. Resolution adapts to the connection — native on a secure context, downscaled on plain-HTTP LAN.1 Codec fallback — the stream negotiates the codec per client and falls back to JPEG when a hardware or WASM decoder isn't available, so older browsers still work. Touch, swipe & pinch — real-time input forwarded to the simulator or emulator. Deeplink toolbar — open supported deeplinks directly from the QA toolbar. Keyboard shortcuts — trigger simulator toolbar actions from the keyboard.

App Center — upload .app.zip / .apk and track builds by status (Backlog / In Progress / Done / Rejected). Session recordings — record and share QA sessions, kept on the relay for ~72 hours, then purged automatically. Screenshot REST endpoint — GET /api/v1/sessions/:sessionId/screenshot for CI and AI agents. Mac resource monitoring — CPU & RAM per agent, to spot overloaded hosts before assigning sessions. Team management — invite links, roles (Admin / Developer / QA / Viewer), and Personal Access Tokens. MCP Server (experimental) — @tapflowio/mcp-server lets Claude Code and other LLM agents control simulators as native tools.

1 On a real LAN, decode-to-present measures in the low tens of milliseconds (p50 ~11–17 ms with the WASM software decoder; faster with WebCodecs on HTTPS); end-to-end "glass-to-glass" latency adds your network's round trip on top. See the performance & latency reference for the full measurements, conditions, and known limitations.

Security & Privacy tapflow is self-hosted by design — build files, device streams, and session recordings stay on infrastructure you control, never sent to a third-party service.

Data Where it stays

App binaries (.app.zip / .apk) Relay storage

Device streams (video · touch) The relay ↔ browser path you host

Session recordings Relay storage; expire after 72h, then purged

Account & team data The relay's SQLite DB

Third-party simulator cloud Not required

LAN-first — the agent ↔ relay leg is internal traffic; the device stream never transits a third party. Authenticated by default off-host — the relay accepts unauthenticated connections only from its own machine (localhost). Browsers reaching it from elsewhere sign in; agents on another machine present an agent-scope token. PAT + roles — Personal Access Tokens carry scopes (builds:write for CI uploads, agent for remote agents), and team roles (Admin / Developer / QA / Viewer) govern dashboard access.

Found a vulnerability? See SECURITY.md. For the full model, read Security & Privacy. Self-Hosting Local (single Mac) Relay and agent on the same machine — ideal for a single developer or small team.

tapflow start Team (separate relay server) Run the relay on a Linux server or dedicated Mac. Each Mac with simulators runs the agent. Relay server: # Recommended: PM2 for automatic restarts npm install -g pm2 tapflow JWT_SECRET=$(openssl rand -hex 32) pm2 start tapflow --name relay -- relay start pm2 save && pm2 startup Each Mac agent: tapflow agent start --relay wss://your-relay-url --token <agent-token>

A relay on a different machine accepts an agent only with an agent-scope token — create one in Settings → Tokens (Admin only). Agents on the relay's own machine (tapflow start) need no token. See Remote relay authentication. For nginx / Caddy reverse proxy setup and external access, see Self-Hosting the Relay.

CLI Reference

Command Description

tapflow start Start relay + agent together (local mode)

tapflow relay start Start relay only

tapflow agent start --relay <url> [--token <pat>] Start agent and connect to a relay (remote relays need an agent-scope token)

tapflow init Scaffold tapflow.config.json

tapflow admin init Create the first admin account (CLI fallback)

tapflow doctor [platform] Diagnose prerequisites (Node, iOS, Android)

tapflow setup [platform] Install & configure the local environment

tapflow devices List available simulators and emulators

tapflow boot <name|udid> Boot a simulator or emulator

tapflow status Show connected agents, devices, active sessions

tapflow reset Shut down all simulators and emulators

tapflow logs Show recent relay log entries

Full reference → CLI docs Documentation www.tapflow.dev Getting Started

Introduction Quick Start Requirements

Setup

Self-Hosting the Relay Security & Privacy Agent Setup Uploading Builds (CI/CD) Scaling Mac Resources

Dashboard

First-time Setup Dashboard Overview

AI Agent

MCP Server (experimental)

Reference

CLI Reference Configuration REST API

Troubleshooting Contributing tapflow is actively developed and PRs are welcome — see CONTRIBUTING.md for branch strategy, commit conventions, and an architecture overview.

For deep dives, the contributor notes cover the SimulatorKit reverse-engineering and the streaming render pipeline. Requirements: Node.js ≥ 20, pnpm ≥ 9 git clone https://github.com/jo-duchan/tapflow.git cd tapflow pnpm install pnpm dev License MIT — Copyright © 2026-present tapflow contributors

tapflow bundles scrcpy-server (Apache-2.0) for Android screen streaming. See NOTICE for full attribution.