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<table class="header">
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    <td colspan="2" rowspan="2" class="width-auto">
      <h1 class="title">krach</h1>
      <span class="subtitle">live coding audio</span>
    </td>
    <th>Version</th>
    <td class="width-min">v1.0</td>
  </tr>
  <tr>
    <th>Updated</th>
    <td class="width-min"><time style="white-space: pre;">2026-03-23</time></td>
  </tr>
  <!-- <tr>
    <th class="width-min">Author</th>
    <td class="width-auto"><a href="https://argmin.xyzhttps://github.com/Bendrien"><cite>Jonas
KöhlerAnyere Bendrien</cite></a></td>
    <th class="width-min">License</th>
    <td>MIT</td>
  </tr> -->
</table>
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<nav id="TOC" role="doc-toc">
<h2 id="toc-title">Contents</h2>
<ul class="incremental">
<li><a href="#what-is-krach" id="toc-what-is-krach">What is
krach?</a></li>
<li><a href="#how-it-works" id="toc-how-it-works">How it works</a></li>
<li><a href="#operator-dsl" id="toc-operator-dsl">Operator DSL</a></li>
<li><a href="#synth-design" id="toc-synth-design">Synth design</a></li>
<li><a href="#pattern-algebra" id="toc-pattern-algebra">Pattern
algebra</a></li>
<li><a href="#architecture" id="toc-architecture">Architecture</a></li>
<li><a href="#install" id="toc-install">Install</a></li>
<li><a href="#links" id="toc-links">Links</a></li>
<li><a href="#credits" id="toc-credits">Credits</a></li>
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</nav>
<h2 id="what-is-krach">What is krach?</h2>
<p>A live coding audio system. Write synths in Python, wire them as a
graph, sequence with composable patterns, hear changes instantly.</p>
<div class="sourceCode" id="cb1"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Define a synth — just a Python function</span></span>
<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> acid_bass() <span class="op">-&gt;</span> krs.Signal:</span>
<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>    freq <span class="op">=</span> krs.control(<span class="st">&quot;freq&quot;</span>, <span class="fl">55.0</span>, <span class="fl">20.0</span>, <span class="fl">800.0</span>)</span>
<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a>    gate <span class="op">=</span> krs.control(<span class="st">&quot;gate&quot;</span>, <span class="fl">0.0</span>, <span class="fl">0.0</span>, <span class="fl">1.0</span>)</span>
<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a>    cutoff <span class="op">=</span> krs.control(<span class="st">&quot;cutoff&quot;</span>, <span class="fl">800.0</span>, <span class="fl">100.0</span>, <span class="fl">4000.0</span>)</span>
<span id="cb1-6"><a href="#cb1-6" aria-hidden="true" tabindex="-1"></a>    env <span class="op">=</span> krs.adsr(<span class="fl">0.005</span>, <span class="fl">0.15</span>, <span class="fl">0.3</span>, <span class="fl">0.08</span>, gate)</span>
<span id="cb1-7"><a href="#cb1-7" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> krs.lowpass(krs.saw(freq), cutoff) <span class="op">*</span> env <span class="op">*</span> <span class="fl">0.55</span></span>
<span id="cb1-8"><a href="#cb1-8" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb1-9"><a href="#cb1-9" aria-hidden="true" tabindex="-1"></a><span class="co"># Define an effect — takes audio input</span></span>
<span id="cb1-10"><a href="#cb1-10" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> reverb(inp: krs.Signal) <span class="op">-&gt;</span> krs.Signal:</span>
<span id="cb1-11"><a href="#cb1-11" aria-hidden="true" tabindex="-1"></a>    room <span class="op">=</span> krs.control(<span class="st">&quot;room&quot;</span>, <span class="fl">0.7</span>, <span class="fl">0.0</span>, <span class="fl">1.0</span>)</span>
<span id="cb1-12"><a href="#cb1-12" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> krs.reverb(inp, room) <span class="op">*</span> <span class="fl">0.8</span></span>
<span id="cb1-13"><a href="#cb1-13" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb1-14"><a href="#cb1-14" aria-hidden="true" tabindex="-1"></a><span class="co"># Create nodes, route, play</span></span>
<span id="cb1-15"><a href="#cb1-15" aria-hidden="true" tabindex="-1"></a>bass <span class="op">=</span> kr.node(<span class="st">&quot;bass&quot;</span>, acid_bass, gain<span class="op">=</span><span class="fl">0.3</span>)</span>
<span id="cb1-16"><a href="#cb1-16" aria-hidden="true" tabindex="-1"></a>verb <span class="op">=</span> kr.node(<span class="st">&quot;verb&quot;</span>, reverb, gain<span class="op">=</span><span class="fl">0.3</span>)</span>
<span id="cb1-17"><a href="#cb1-17" aria-hidden="true" tabindex="-1"></a>bass <span class="op">&gt;&gt;</span> verb                                       <span class="co"># route signal</span></span>
<span id="cb1-18"><a href="#cb1-18" aria-hidden="true" tabindex="-1"></a>bass <span class="op">@</span> kr.seq(<span class="st">&quot;A2&quot;</span>, <span class="st">&quot;D3&quot;</span>, <span class="va">None</span>, <span class="st">&quot;E2&quot;</span>).over(<span class="dv">2</span>)      <span class="co"># play pattern</span></span>
<span id="cb1-19"><a href="#cb1-19" aria-hidden="true" tabindex="-1"></a>bass[<span class="st">&quot;cutoff&quot;</span>] <span class="op">=</span> <span class="dv">1200</span>                               <span class="co"># set control</span></span></code></pre></div>
<h2 id="how-it-works">How it works</h2>
<p><strong>Python</strong> defines synths and patterns.
<strong>Rust</strong> runs the engine. <strong>FAUST</strong>
JIT-compiles DSP to native audio.</p>
<pre><code>Python (define)          Rust (execute)              Audio
──────────────           ──────────────              ─────
kr.node(&quot;bass&quot;, fn)  →  FAUST JIT compile       →  CoreAudio
bass @ pattern       →  pattern → curves         →  block-rate automation
bass[&quot;cutoff&quot;] = v   →  SetControl               →  node parameter
bass &gt;&gt; verb         →  graph rebuild + crossfade →  seamless routing</code></pre>
<p>Two symbols: <code>kr</code> (the audio graph) and <code>krs</code>
(DSP primitives). That’s the entire API.</p>
<h2 id="operator-dsl">Operator DSL</h2>
<p>Everything is a node. Routing uses <code>&gt;&gt;</code>. Patterns
use <code>@</code>. Controls use <code>[]</code>.</p>
<div class="sourceCode" id="cb3"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>bass <span class="op">=</span> kr.node(<span class="st">&quot;bass&quot;</span>, acid_bass, gain<span class="op">=</span><span class="fl">0.3</span>)</span>
<span id="cb3-2"><a href="#cb3-2" aria-hidden="true" tabindex="-1"></a>verb <span class="op">=</span> kr.node(<span class="st">&quot;verb&quot;</span>, reverb, gain<span class="op">=</span><span class="fl">0.3</span>)</span>
<span id="cb3-3"><a href="#cb3-3" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb3-4"><a href="#cb3-4" aria-hidden="true" tabindex="-1"></a>bass <span class="op">&gt;&gt;</span> verb                           <span class="co"># route signal</span></span>
<span id="cb3-5"><a href="#cb3-5" aria-hidden="true" tabindex="-1"></a>bass <span class="op">&gt;&gt;</span> (verb, <span class="fl">0.4</span>)                    <span class="co"># route with send level</span></span>
<span id="cb3-6"><a href="#cb3-6" aria-hidden="true" tabindex="-1"></a>bass <span class="op">@</span> kr.seq(<span class="st">&quot;A2&quot;</span>, <span class="st">&quot;D3&quot;</span>).over(<span class="dv">2</span>)      <span class="co"># play pattern</span></span>
<span id="cb3-7"><a href="#cb3-7" aria-hidden="true" tabindex="-1"></a>bass <span class="op">@</span> <span class="st">&quot;A2 D3 ~ E2&quot;</span>                   <span class="co"># mini-notation shorthand</span></span>
<span id="cb3-8"><a href="#cb3-8" aria-hidden="true" tabindex="-1"></a>bass <span class="op">@</span> <span class="va">None</span>                            <span class="co"># hush</span></span>
<span id="cb3-9"><a href="#cb3-9" aria-hidden="true" tabindex="-1"></a>bass[<span class="st">&quot;cutoff&quot;</span>] <span class="op">=</span> <span class="dv">1200</span>                  <span class="co"># set control</span></span>
<span id="cb3-10"><a href="#cb3-10" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb3-11"><a href="#cb3-11" aria-hidden="true" tabindex="-1"></a><span class="cf">with</span> kr.transition(bars<span class="op">=</span><span class="dv">8</span>):           <span class="co"># all changes fade over 8 bars</span></span>
<span id="cb3-12"><a href="#cb3-12" aria-hidden="true" tabindex="-1"></a>    bass[<span class="st">&quot;gain&quot;</span>] <span class="op">=</span> <span class="fl">0.8</span></span>
<span id="cb3-13"><a href="#cb3-13" aria-hidden="true" tabindex="-1"></a>    kr.tempo <span class="op">=</span> <span class="dv">140</span></span></code></pre></div>
<h2 id="synth-design">Synth design</h2>
<p>Write DSP functions in Python. They transpile to FAUST and
JIT-compile via LLVM. Hot reload on save. Auto-smoothing on all non-gate
parameters.</p>
<div class="sourceCode" id="cb4"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> kick() <span class="op">-&gt;</span> krs.Signal:</span>
<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a>    gate <span class="op">=</span> krs.control(<span class="st">&quot;gate&quot;</span>, <span class="fl">0.0</span>, <span class="fl">0.0</span>, <span class="fl">1.0</span>)</span>
<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a>    env <span class="op">=</span> krs.adsr(<span class="fl">0.001</span>, <span class="fl">0.25</span>, <span class="fl">0.0</span>, <span class="fl">0.05</span>, gate)</span>
<span id="cb4-4"><a href="#cb4-4" aria-hidden="true" tabindex="-1"></a>    <span class="cf">return</span> krs.sine_osc(<span class="fl">55.0</span> <span class="op">+</span> env <span class="op">*</span> <span class="fl">200.0</span>) <span class="op">*</span> env <span class="op">*</span> <span class="fl">0.9</span></span>
<span id="cb4-5"><a href="#cb4-5" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb4-6"><a href="#cb4-6" aria-hidden="true" tabindex="-1"></a>kr.node(<span class="st">&quot;kick&quot;</span>, kick, gain<span class="op">=</span><span class="fl">0.8</span>)</span>
<span id="cb4-7"><a href="#cb4-7" aria-hidden="true" tabindex="-1"></a>kr.play(<span class="st">&quot;kick&quot;</span>, kr.hit() <span class="op">*</span> <span class="dv">4</span>)</span></code></pre></div>
<h2 id="pattern-algebra">Pattern algebra</h2>
<p>TidalCycles-inspired composable patterns. Every operation returns a
pattern.</p>
<div class="sourceCode" id="cb5"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>a <span class="op">+</span> b           <span class="co"># sequence</span></span>
<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a>a <span class="op">|</span> b           <span class="co"># layer (simultaneous)</span></span>
<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a>p <span class="op">*</span> <span class="dv">4</span>           <span class="co"># repeat</span></span>
<span id="cb5-4"><a href="#cb5-4" aria-hidden="true" tabindex="-1"></a>p.over(<span class="dv">2</span>)       <span class="co"># stretch to 2 cycles</span></span>
<span id="cb5-5"><a href="#cb5-5" aria-hidden="true" tabindex="-1"></a>p.swing(<span class="fl">0.67</span>)   <span class="co"># swing feel</span></span>
<span id="cb5-6"><a href="#cb5-6" aria-hidden="true" tabindex="-1"></a>p.mask(<span class="st">&quot;1 1 0 1&quot;</span>)           <span class="co"># suppress events</span></span>
<span id="cb5-7"><a href="#cb5-7" aria-hidden="true" tabindex="-1"></a>p.sometimes(<span class="fl">0.3</span>, reverse)   <span class="co"># probabilistic transform</span></span>
<span id="cb5-8"><a href="#cb5-8" aria-hidden="true" tabindex="-1"></a>p.every(<span class="dv">4</span>, reverse)          <span class="co"># transform every 4th cycle</span></span>
<span id="cb5-9"><a href="#cb5-9" aria-hidden="true" tabindex="-1"></a>p.spread(<span class="dv">3</span>, <span class="dv">8</span>)               <span class="co"># euclidean rhythm</span></span>
<span id="cb5-10"><a href="#cb5-10" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb5-11"><a href="#cb5-11" aria-hidden="true" tabindex="-1"></a>kr.struct(rhythm, melody)    <span class="co"># impose rhythm onto melody</span></span>
<span id="cb5-12"><a href="#cb5-12" aria-hidden="true" tabindex="-1"></a>kr.cat(a, b, c)             <span class="co"># play each for 1 cycle, loop</span></span>
<span id="cb5-13"><a href="#cb5-13" aria-hidden="true" tabindex="-1"></a>kr.p(<span class="st">&quot;x . x . x . . x&quot;</span>)    <span class="co"># mini-notation</span></span></code></pre></div>
<h2 id="architecture">Architecture</h2>
<p>Single-process Rust binary. Patterns compile to block-rate automation
curves (~172 updates/sec). Lock-free audio thread. FAUST hot-reload.</p>
<pre><code>noise/
├── audio-engine/      Rust — graph runtime, crossfade, automation
├── audio-faust/       Rust — FAUST LLVM JIT, hot reload
├── pattern-engine/    Rust — pattern sequencer, rational time, curve compiler
├── krach-engine/      Rust — unified binary (one process, one socket)
├── krach/             Python — live coding REPL, IR, DSP transpiler, patterns
└── krach-mcp/         Python — MCP server (25 tools for Claude Code to drive krach)</code></pre>
<h2 id="install">Install</h2>
<div class="sourceCode" id="cb7"><pre
class="sourceCode bash"><code class="sourceCode bash"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Prerequisites: macOS, Rust, Python 3.13+, uv, FAUST + LLVM</span></span>
<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a><span class="ex">brew</span> install faust llvm</span>
<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a><span class="bu">export</span> <span class="va">LLVM_SYS_181_PREFIX</span><span class="op">=</span><span class="va">$(</span><span class="ex">brew</span> <span class="at">--prefix</span> llvm<span class="va">)</span></span>
<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a><span class="fu">git</span> clone https://github.com/krachio/noise.git <span class="kw">&amp;&amp;</span> <span class="bu">cd</span> noise</span>
<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a><span class="ex">cargo</span> build <span class="at">--release</span> <span class="at">-p</span> krach-engine</span>
<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a><span class="bu">cd</span> krach <span class="kw">&amp;&amp;</span> <span class="ex">uv</span> sync <span class="kw">&amp;&amp;</span> <span class="bu">cd</span> ..</span>
<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a><span class="ex">./bin/krach</span></span></code></pre></div>
<h2 id="links">Links</h2>
<p><a href="https://krach.io/noise/docs/">Documentation</a> · <a
href="https://github.com/krachio/noise">GitHub</a> · <a
href="https://krach.io/noise/try/">Try it</a> · <a
href="https://github.com/krachio/noise/blob/main/LICENSE">GPL-2.0-or-later</a></p>
<h2 id="credits">Credits</h2>
<p>Design: <a
href="https://github.com/owickstrom/the-monospace-web">the-monospace-web</a></p>
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