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An MCP server + browser SDK that gives AI coding assistants direct sensory access to a live web application. Audio, visuals, performance, network, security, and console — captured from the browser, analyzed in real time, delivered via MCP.

"The beat sounds muddy" → your AI captures 3 seconds, measures the spectral centroid at 580 Hz with 45% energy below 250 Hz, and tells you exactly why.

What It Does

How It Works

Browser (Web Audio API)
    ↓ MediaRecorder taps the AudioContext output node
    ↓ Uploads WebM blob via HTTP POST
Express Middleware (your dev server)
    ↓ Stores captures in memory, dispatches commands via SSE
MCP Server (stdio — runs inside your IDE)
    ↓ Retrieves captures, sends to CodedSwitch analysis API
AI Coding Assistant
    → "Your bass band is 42% of the mix (high), spectral centroid
       is 580 Hz (muddy), and timing jitter is 23ms — the scheduler
       is drifting under load."

The key difference from every other audio MCP: this taps the Web Audio graph directly, bypassing room acoustics, microphone hardware, and the need to export files.

Quick Start

1. Install

npm install webear

2. Add the Express middleware to your dev server

import express from 'express'
import { webearMiddleware } from 'webear/middleware'

const app = express()
app.use(express.json())

// Mount the audio debug bridge (automatically disabled in production)
app.use('/api/webear', webearMiddleware())

app.listen(5000)

3. Add the client snippet to your web app

Option A — auto-detect everything (Tone.js or raw Web Audio)

import WebEar from 'webear/client'
WebEar.init()

Option B — explicit AudioContext

const ctx = new AudioContext()
const masterGain = ctx.createGain()
masterGain.connect(ctx.destination)

WebEar.init({ audioContext: ctx, outputNode: masterGain })

Option C — Tone.js project

import * as Tone from 'tone'
WebEar.init({ toneJs: true })

Option D — Three.js WebGL Game

import * as THREE from 'three'
const listener = new THREE.AudioListener()
camera.add(listener)
WebEar.init({ tapNode: listener.getInput() })

Option E — plain script tag

<script src="node_modules/webear/client-snippet.js"></script>
<script>WebEar.init()</script>

4. Configure your IDE

Claude Code (.mcp.json in project root):

{
  "mcpServers": {
    "webear": {
      "command": "npx",
      "args": ["webear"],
      "env": {
        "WEBEAR_BASE_URL": "http://localhost:5000",
        "CODEDSWITCH_API_KEY": "your-key-here"
      }
    }
  }
}

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "webear": {
      "command": "npx",
      "args": ["webear"],
      "env": {
        "WEBEAR_BASE_URL": "http://localhost:5000",
        "CODEDSWITCH_API_KEY": "your-key-here"
      }
    }
  }
}

Windsurf (mcp_config.json):

{
  "webear": {
    "command": "npx",
    "args": ["webear"],
    "disabled": false,
    "env": {
      "WEBEAR_BASE_URL": "http://localhost:5000",
      "CODEDSWITCH_API_KEY": "your-key-here"
    }
  }
}

5. Get an API key — optional, and not to start

analyze_audio works with no key and no account. If ffmpeg is on your PATH, it decodes and analyzes the capture on your machine and returns a basic report: duration, loudness, peak level and whether the audio is clipping. Nothing is uploaded. Try the tool before you sign up for anything.

A key unlocks the parts that need more than arithmetic:

To get one:

1. Create a free account at codedswitch.com.
2. Go to codedswitch.com/developer (also in the account menu as Developer API).
3. Click Generate API Key — that value is your CODEDSWITCH_API_KEY. Keys start with wbr_.

Free tier: 50 analyses/day. No credit card required.

6. Start your dev server, open your app, play audio, then ask your AI:

"Capture 3 seconds and tell me why the bass sounds muddy."

"Compare the audio before and after my last commit."

"Is there any clipping in the high-frequency range?"

Example Output

analyze_audio

── Audio Analysis Report ──────────────────────────────
Duration:          3.02s

── Loudness ─────────────────────────────────────────
RMS:               -12.4 dBFS
Peak:              -1.2 dBFS
Dynamic range:     11.2 dB
Crest factor:      3.63
Clipping:          none

── Tone ──────────────────────────────────────────────
Spectral centroid: 2847 Hz
DC offset:         0.00012 (ok)

── Frequency Bands ───────────────────────────────────
Sub  (20-80 Hz):   8.2%
Bass (80-250 Hz):  22.1%
Mid  (250-2k Hz):  38.4%
Hi-mid (2-6k Hz):  21.8%
High (6k+ Hz):     9.5%

── Rhythm ────────────────────────────────────────────
Estimated BPM:     92
Onset count:       12
Timing jitter:     4.2 ms std dev

── Summary ───────────────────────────────────────────
Loudness: -12.4 dBFS RMS, peak -1.2 dBFS. Tone: balanced (centroid 2847 Hz).
Band mix — sub: 8% | bass: 22% | mid: 38% | hi-mid: 22% | high: 10%.
Rhythm: estimated 92 BPM, 12 onsets detected. Timing: very tight (< 5 ms jitter).

diff_audio

── Audio Diff: a1b2c3d4… → e5f6g7h8… ──

── Loudness ──────────────────────────────────────────
  RMS: -14.2 dBFS → -12.4 dBFS  (+1.8 dBFS)
⚠ Peak: -3.1 dBFS → -0.2 dBFS  (+2.9 dBFS)
⚠ CLIPPING INTRODUCED — gain staging regression

── Tone ──────────────────────────────────────────────
⚠ Spectral centroid: 2847.0 Hz → 1920.0 Hz  (-927.0 Hz)

── Interpretation ────────────────────────────────────
A gain bug was introduced that causes clipping.
Tonal character changed noticeably — EQ or filter behaviour may have shifted.

Configuration

Environment Variables

Middleware Options

webearMiddleware({
  maxCaptures: 50,       // Max captures in memory (default: 50)
  maxAgeMins: 10,        // Auto-evict after N minutes (default: 10)
  maxUploadBytes: 50e6,  // Max upload size (default: 50MB)
  devOnly: true,         // Disable in production (default: true)
})

Client Options

WebEar.init({
  audioContext: myCtx,             // Your AudioContext instance
  outputNode: myGainNode,          // The node to tap (defaults to destination)
  toneJs: true,                    // Auto-detect Tone.js context
  bridgeBase: '/api/webear',  // Override API path
  devOnly: true,                   // Only init outside of production (default: true)
})

Requirements

• Node.js >= 18
• A browser that supports MediaRecorder (Chrome, Firefox, Edge, Safari 14+)
• A CODEDSWITCH_API_KEY for analysis (free at codedswitch.com)

Who Is This For?

• Web Audio / Tone.js developers — debug beats, synths, effects, and mixing without leaving your IDE
• Game audio developers — verify sound effects, spatial audio, and mixing in real-time
• Music app builders — catch regressions between code changes with diff_audio
• Podcast / streaming apps — validate audio quality, levels, and encoding
• Anyone whose app makes sound — if it has a Web Audio graph, your AI can now hear it

Why Not Just Use the Microphone?

Microphone MCPs capture room sound — your fan noise, chair creaks, and room reverb are all in the recording. webear taps the Web Audio API before it hits the DAC, giving you a clean digital signal with no room artifacts.

Web Perception — Full Sensor Suite

WebEar started as audio-only. Web Perception expands it to 6 senses:

Install the full browser SDK

import { WebPerception } from 'webear/perception'

WebPerception.init({
  apiKey: 'wbr_YOUR_API_KEY',
  relayUrl: 'https://www.codedswitch.com',
  sensors: ['ear', 'eye', 'sense', 'nerve', 'shield', 'log'],
})

Or use a single sensor:

import { WebEar } from 'webear/perception'

WebEar.init({
  apiKey: 'wbr_YOUR_API_KEY',
  ear: { audioContext: myCtx, audioNode: masterGain },
})

Connect via MCP (hosted relay — no local server required)

{
  "mcpServers": {
    "webear": {
      "url": "https://www.codedswitch.com/api/webear/mcp/sse",
      "headers": {
        "Authorization": "Bearer wbr_YOUR_API_KEY"
      }
    }
  }
}

Available MCP Tools

Get an API Key

1. Create a free account at codedswitch.com.
2. Open codedswitch.com/developer — also linked as Developer API in the account menu.
3. Click Generate API Key and copy it. Keys start with wbr_.

Free tier: 50 analyses/day, no credit card required.

Changelog

2.0.1

• Fixed the getting-started path for API keys. The previous instruction ("Settings → WebEar") was wrong — there is no WebEar section under Settings. Keys live at codedswitch.com/developer (linked as Developer API in the account menu). Both the Quick Start and the Web Perception sections now point to the correct place.
• The SDK's "missing API key" console error now links straight to the key page.

Contributing

See CONTRIBUTING.md.

License

MIT — see LICENSE

Author

Built by @asume21 — CodedSwitch

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