ctrlb-decompose

Turn millions of noisy log lines into compact patterns with typed variables, quantiles, anomalies, and LLM-ready output.

Runs as a CLI, in the browser via WASM, or as a Rust library — no logs ever leave your machine.

Website: ctrlb.ai

Try it in 60 seconds

No install, no signup — the whole pipeline (CLP encoding, Drain3 clustering, typing, stats) runs client-side in WebAssembly.

1. Open ctrlb.ai/decompose
2. Paste or drop in a log file (or click Generate Example to try it with sample data)
3. Hit Analyze and watch thousands of lines collapse into a handful of typed patterns

Before / after

A real 56,482-line Apache-style error log, decomposed live in the browser demo:

Before — raw, repetitive, un-skimmable:

[Thu Jun 09 06:07:05 2005] [error] env.createBean2(): Factory error creating channel.jni:jni ( channel.jni, jni)
[Thu Jun 09 06:07:05 2005] [error] config.update(): Can't create channel.jni:jni
[Thu Jun 09 06:07:05 2005] [error] env.createBean2(): Factory error creating vm: ( vm, )
[Thu Jun 09 06:07:05 2005] [error] config.update(): Can't create vm:
[Thu Jun 09 06:07:05 2005] [error] env.createBean2(): Factory error creating worker.jni:onStartup ( worker.jni, onStartup)
... 56,477 more lines like this ...

After — 25 typed patterns, ranked by volume, in 246ms:

ctrlb-decompose: 56,482 lines → 25 patterns (100.0% reduction)
Time range: 06:07:04 UTC → 03:49:01 UTC

Pattern #1 [ERROR] (20,862 occurrences, 36.9%)
  "<TS> [error] [client <*>] <*> <*> <*> <*> <*>"
  Variables:
    IPv4:   456 unique values
    String: 46 unique values
    Enum:   does (100.0%), to (0.0%)
    Enum:   not (100.0%), serve (0.0%)
    Enum:   exist (100.0%), directory (0.0%)
    String: 81 unique values

Pattern #2 (7,044 occurrences, 12.5%)
  ...

Output modes

HUMAN mode — colored, for terminal investigation:

LLM OPTIMIZE mode — compact markdown for feeding into an LLM:

Resources

How It Works

ctrlb-decompose uses a two-stage normalization and clustering pipeline that processes logs in a single streaming pass with minimal memory footprint.

                         ┌──────────────────────────────────────────────┐
                         │            ctrlb-decompose pipeline          │
                         └──────────────────────────────────────────────┘

  Raw Log Lines
       │
       ▼
┌──────────────┐    Strip & parse timestamps (ISO 8601, Apache,
│  Timestamp   │    syslog, Unix epoch, etc.) into normalized
│  Extraction  │    <TS> markers with DateTime values.
└──────┬───────┘
       │
       ▼
┌──────────────┐    Replace integers, floats, IPs, and strings
│     CLP      │    with compact placeholder bytes. Structurally
│   Encoding   │    identical lines now produce the same "logtype."
└──────┬───────┘
       │
       ▼
┌──────────────┐    Tree-based similarity clustering (Drain3) groups
│   Drain3     │    logtypes into patterns. Differing tokens become
│  Clustering  │    <*> wildcards. Incremental — no second pass needed.
└──────┬───────┘
       │
       ▼
┌──────────────┐    Merge CLP-decoded values with Drain3 wildcard
│   Variable   │    positions. Classify each variable into semantic
│  Extraction  │    types: IPv4, UUID, Duration, Enum, Integer, etc.
│  & Typing    │
└──────┬───────┘
       │
       ▼
┌──────────────┐    DDSketch quantiles (p50/p99), HyperLogLog
│  Statistics  │    cardinality estimation, top-k values, temporal
│ Accumulation │    bucketing, and reservoir-sampled example lines.
└──────┬───────┘
       │
       ▼
┌──────────────┐    Frequency spikes, error cascades, low-cardinality
│   Anomaly    │    flags, bimodal distributions, and clustered
│  Detection   │    numeric detection.
└──────┬───────┘
       │
       ▼
┌──────────────┐    Keyword-based severity (ERROR > WARN > INFO > DEBUG),
│   Scoring    │    temporal co-occurrence, shared variable correlation,
│ & Correlation│    and error cascade detection across patterns.
└──────┬───────┘
       │
       ▼
┌──────────────┐
│    Output    │──── Human (ANSI terminal) / LLM (compact markdown) / JSON
└──────────────┘

Stage 1 — CLP Encoding

CLP (Compressed Log Processor) encoding normalizes variable tokens into typed placeholders, so structurally identical lines produce identical logtypes regardless of the actual values:

Input:   "Request from 10.0.1.15 completed in 45ms status=200"
Logtype: "Request from <dict> completed in <float>ms status=<int>"

Stage 2 — Drain3 Clustering

The Drain algorithm builds a prefix tree over logtypes and groups them by token similarity (configurable threshold, default 0.4). Where tokens diverge, the template gains a <*> wildcard. This runs incrementally — each line is processed once with no second pass.

Variable Classification

Extracted variables are classified into semantic types for richer analysis:

Memory Efficiency

• Drain3 clusters: O(k) with LRU eviction (default 10k max)
• Quantiles: DDSketch — fixed ~200 bytes per numeric slot, no raw value storage
• Cardinality: HyperLogLog++ — ~200 bytes per high-cardinality variable
• Examples: Reservoir sampling — bounded buffer per pattern

Installation

macOS (Homebrew)

brew tap ctrlb-hq/tap
brew install ctrlb-decompose

Debian / Ubuntu

curl -LO https://github.com/ctrlb-hq/ctrlb-decompose/releases/download/v0.1.0/ctrlb-decompose_0.1.0-1_amd64.deb
sudo dpkg -i ctrlb-decompose_0.1.0-1_amd64.deb

Build from source

git clone https://github.com/ctrlb-hq/ctrlb-decompose.git
cd ctrlb-decompose
cargo build --release
# Binary at target/release/ctrlb-decompose

Usage

# Pipe from stdin
cat /var/log/syslog | ctrlb-decompose

# Read from file
ctrlb-decompose server.log

# LLM-optimized output (compact, token-efficient)
ctrlb-decompose --llm app.log

# JSON output
ctrlb-decompose --json app.log

# Top 10 patterns with 3 example lines each
ctrlb-decompose --top 10 --context 3 app.log

Options

ctrlb-decompose [OPTIONS] [FILE]

Arguments:
  [FILE]          Log file path (reads stdin if omitted or "-")

Options:
      --human         Human-readable output with colors (default)
      --llm           LLM-optimized compact markdown
      --json          Structured JSON output
      --top <N>       Show top N patterns (default: 20)
      --context <N>   Example lines per pattern (default: 0)
      --no-color      Disable ANSI colors
      --no-banner     Suppress header/footer
  -q, --quiet         Suppress progress messages
  -h, --help          Show help
  -V, --version       Show version

Output Formats

ctrlb-decompose has three output modes, all driven off the same analysis pass — pick the one that fits where you're reading it. See the before/after screenshots above for --human and --llm side by side in the browser demo.

┌──────────────────────────────────────────────────────────────────┐
│ ctrlb-decompose: 80,000 lines -> 3 patterns (100.0% reduction) │
└──────────────────────────────────────────────────────────────────┘
  Time range: 14:22:01 UTC -> 16:35:10 UTC

Pattern #1 (75,211 occurrences, 94.0%)
  "<TS> INFO [<*>] Request from <*> completed in <*> status=<*>"
  Variables:
    HexID:    804 unique values
    IPv4:     27 unique values
    Duration: mean=46, p50=45, p99=116, min=3, max=169
    Integer:  mean=224, p50=198, p99=498, min=200, max=503

Pattern #2 [WARN] (2,773 occurrences, 3.5%)
  "<TS> WARN [<*>] Connection pool exhausted, waiting <*>"
  Variables:
    HexID:    726 unique values
    Duration: mean=526, p50=529, p99=889, min=150, max=900

{
  "summary": {
    "total_lines": 80000,
    "pattern_count": 3,
    "patterns_shown": 1,
    "patterns_omitted": 2,
    "time_range": {
      "start": "2026-08-21T14:22:01.051+00:00",
      "end": "2026-08-21T16:35:10.707+00:00"
    }
  },
  "patterns": [
    {
      "id": 1,
      "template": "<TS> INFO [<*>] Request from <*> completed in <*> status=<*>",
      "count": 75211,
      "frequency_pct": 94.0,
      "severity": "info",
      "variables": [
        { "slot": 0, "type": "HexID", "unique_count": 804 },
        { "slot": 1, "type": "IPv4", "unique_count": 27 },
        { "slot": 2, "type": "Duration", "unique_count": 157 },
        { "slot": 3, "type": "Integer", "unique_count": 4 }
      ]
    }
  ]
}

Claude Code Plugin

Use ctrlb-decompose directly from Claude Code — no CLI knowledge needed. The plugin installs ctrlb-decompose automatically and lets you analyze logs just by asking.

Install

/plugin marketplace add ctrlb-hq/ctrlb-decompose
/plugin install ctrlb-decompose@ctrlb-hq

Usage

Just describe what you want in plain language:

• "Analyze the errors in /var/log/app.log"
• "What are the most common patterns in this log file?"
• "Summarize these logs and highlight anomalies"

Claude will check if ctrlb-decompose is installed (and walk you through installation if not), run the analysis, and explain the results — surfacing errors first, calling out anomalies, and suggesting what to investigate next.

See github.com/ctrlb-hq/ctrlb-decompose/tree/main/plugin for full details.

License

MIT