LOGAN - Log Analyzer

A fast, AI-ready log file viewer built with Electron. Handles tens of millions of lines with virtual scrolling, integrates with AI agents via MCP (75+ tools), connects to live serial/logcat/SSH streams, decodes binary/tokenized formats, and provides deep analysis and correlation tools — all in one desktop app.

TL;DR

Download and run — grab the latest build from GitHub Releases:

Platform	File
Linux	`.AppImage` or `.deb`
Windows	`LOGAN.Setup.x.x.x.exe`

Build from source:

git clone https://github.com/SolidKeyAB/logan.git
cd logan
npm install
npm start

Linux only: sudo apt install -y build-essential cmake python3 before npm install.

Features

Core Viewer

Virtual scrolling — Constant memory usage and smooth 60fps, even on files with tens of millions of lines
Fast search — Powered by ripgrep (10-100x faster), with regex, wildcard, whole word, and case-sensitive modes
Multiple tabs — Open and switch between files without losing state
Minimap — Bird's-eye overview with color-coded error/warning indicators, click to jump
Jump to problem — A cheap severity index lets you leap to the next/previous fatal/error/warning with F8 / Shift+F8, even on huge files
Start-here pill — On open, a severity pill appears in the tab bar (fatal/error/warning counts) with a pulldown that jumps to the first problem, suggests a column layout, and opens the full brief — remembered per file
Word wrap & zoom — Toggle wrapping, adjust font size with Ctrl+/- or mouse wheel
Columns panel — Auto-detect delimited/whitespace-aligned columns; name them, show/hide/mute, freeze the header, drag-to-resize, and save reusable column layouts and column patterns (grok/regex)
Fold repeats — One-click top-bar toggle that collapses repeating blocks in the viewer into ▶ ×N headers you click to expand — compress a noisy log while keeping its structure
JSON auto-format — Pretty-print JSON files on open

AI Agent Integration

Setup Wizard — Guided setup: auto-detects Claude Code CLI and configures the agent connection
MCP support — 75+ tools auto-discovered by Claude Code, Cursor, and other MCP clients via .mcp.json
Agent Chat tab — Bidirectional messaging between LOGAN and AI agents with SSE real-time bridge
Claude Code integration — Launch Claude Code directly from LOGAN with full MCP tool access
Built-in agent — One-click launch from the Chat tab, handles triage/search/crash analysis/bookmarking
HTTP API — Full REST API for custom agents (bash, Node.js, Python) — see LOGAN-AGENT.md
Connection indicator — Shows agent name and status, enforces single-agent connection
Custom agent scripts — Point to your own agent via ~/.logan/agent-config.json
Interrupt (⏹ Stop) — Stop the agent's current task without killing the session; it acknowledges and goes back to waiting
Findings & reports — The agent pins clickable findings in the viewer (logan_report_finding), hands off a whole batch for you to tick through (logan_import_findings), and saves a Jira-ready Log Analysis Report (logan_save_report)
Evidence pack — One compact briefing (severity, crashes, components, discovered fields, filter hints, optional baseline delta) instead of dozens of exploratory calls (logan_evidence_pack)
Logs + environment — Attach the static capture context (build id, firmware, device, feature flags) as typed facts that auto-inject into briefings and baselines (logan_context_attach)
Session memory — A per-file scratchpad the agent writes so it can resume after a reconnect (logan_memory_read/logan_memory_write)
Agent-driven charts — The agent can render trend charts straight into the Trends panel (logan_trend_show)
Investigation patterns — The agent's investigative steps are recorded and can be saved as named, re-runnable, composable templates with requirement pre-flighting (see docs/INVESTIGATION_TEMPLATES.md)
Run-vs-run diff — Semantic template diff of a failing run against a last-known-good one — what shapes are new, vanished, or shifted (logan_diff_runs)

Live Connections

Serial monitor — Connect to serial ports with auto-device discovery
Android logcat — Stream logcat output with device listing
SSH shell — Remote log tailing via SSH with key/password auth
Datadog — Fetch logs directly from Datadog APIs
Multi-connection — Up to 4 parallel connections, each with its own live card and density minimap
Session recording — Save live sessions to file for later analysis
SSH profiles — Save, load, and manage connection profiles; auto-import from ~/.ssh/config
SFTP browser — Browse and download remote files

Analysis & Filtering

Log analysis — Pattern detection, duplicate grouping, level distribution, and time range stats
Context Search — Define multi-pattern contexts (must + clue patterns) with proximity-based correlation for root cause analysis; tree view and timeline density bar
Advanced filtering — Multi-group filter expressions (AND/OR), level filters, include/exclude patterns, context lines
Time gap detection — Find gaps between timestamps with configurable thresholds
Crash investigation — Deep-dive into crash sites with surrounding context and auto-bookmarking
Component analysis — Investigate a specific component's health across the log
Time-range analysis — Focus on a specific time window
Baseline comparison — Save log fingerprints and compare future logs against them to detect regressions
Search configs — Persistent multi-pattern search with color-coded highlighting, batched with live progress and per-config found-counts (Ctrl+8)
Pattern distance — Measure how far two patterns sit from each other (line gaps): between two search configs, or ad hoc via right-click → Distance from "..." with an over-the-log diagram and click-to-jump
Trends — Discover log variables (key=value/JSON), search them by name, and chart any field over time, as value-flips, or correlated with an event; booleans chart as a 0/1 step line
Signals — Overlay multiple numeric signals (including MF4 channels) on one shared time axis with normalize toggle and click-to-line
Cadence / missing-sequence — Pick a repeating event, auto-detect its period, and flag skipped occurrences and drift with a negative-space strip and click-to-line
Recipes — Save the agent's investigation steps as named, re-runnable recipes; replay one on any log to search, trend, and pin clickable findings in one click

Multi-file & Correlation

Single session — Combine several open files into one continuous read-only view (no on-disk merge) so every tool runs across the set at once
Time Sync — Merge 2+ files onto one wall-clock timeline, colour-tagged by source, with click-to-line — and optionally merge to file for a materialized interleaved log
Run-vs-run diff — Fold two runs into message templates and set-diff them: new shapes, vanished shapes, and frequency shifts between a failing run and a good one
Compare & baseline — Side-by-side diff view, plus fingerprint baselines to catch regressions across runs

Decoding & Formats

Esotrace / vtrace decode — Byte-identical decode of binary vtrace logs into the official 11-column format, on demand from the toolbar or auto-detected on open
Sherlog token decode — Expand @LOG <id> {json} tokenized lines back into readable text using a discoverable token database
Column patterns — Grok (%{name}) / paint-tokens / raw-regex → a compiled named-capture regex that drives live columns over any format

Saved setup & portability

Saved panel — Every saveable entity (search configs, sessions, column layouts/patterns, highlight groups, bookmark sets, trend properties, baselines, investigations, contexts, constants) is enumerable in one searchable panel — apply, reveal, or copy each
Portable catalogue — Export your reusable global setup to a single .logan-pack file (optionally encrypted) and import it on another machine

Annotations

Bookmarks — Mark lines with comments and colors, save/load bookmark sets, export
Highlights — Color-code patterns with regex support, per-file or global, organized in groups
Notes drawer — Freeform notes per file with auto-save and Save-As (Ctrl+Shift+N)
Save snippets — Extract selected line ranges to .notes.txt files

Split & Diff

File splitting — Break huge files into manageable parts
Split view — View two files side by side
Diff view — Compare files with aligned hunk display, additions/deletions/modifications

Media

Video sync — Open a screen recording alongside logs, set a sync point, click lines to seek video (Ctrl+9). Plays MP4/WebM/Ogg directly; AVI/MKV/WMV are auto-converted to MP4 via ffmpeg (cached per file)
Image viewer — View PNG, JPG, SVG images with zoom in the bottom panel

Built-in Tools

Tabbed terminal — Quake-style drop-down with multiple shells and SSH sessions (Ctrl+`)
Folder browser — Open folders, browse files, search across multiple files
Activity history — Track searches, filters, bookmarks, and other actions per file (Ctrl+7)

Persistence

Per-file .logan/ sidecar storage for bookmarks, highlights, notes, video sync, and history
Global ~/.logan/ for highlight groups, bookmark sets, baselines, and settings
State survives across sessions — reopen a file and everything is restored

Requirements

Node.js 18+
ripgrep (optional, recommended for fast search)

Installing ripgrep

macOS:

brew install ripgrep

Ubuntu/Debian:

sudo apt install ripgrep

Windows:

choco install ripgrep

Arch Linux:

sudo pacman -S ripgrep

If ripgrep is not installed, LOGAN falls back to a stream-based search.

Installation

Download Pre-built Packages

Download the latest release from GitHub Releases.

Platform	Download
macOS (Apple Silicon)	`LOGAN-x.x.x-arm64.dmg`
macOS (Intel)	`LOGAN-x.x.x-x64.dmg`
Linux (AppImage)	`LOGAN-x.x.x.AppImage`
Linux (Debian)	`logan_x.x.x_amd64.deb`
Windows (Installer)	`LOGAN.Setup.x.x.x.exe`
Windows (Portable)	`LOGAN.x.x.x.exe`

Build from Source

Linux (Debian/Ubuntu) prerequisites — needed for native modules (node-pty, better-sqlite3):

sudo apt update
sudo apt install -y build-essential cmake python3

Then build:

git clone https://github.com/SolidKeyAB/logan.git
cd logan
npm install
npm start        # builds and launches LOGAN

To package a distributable binary for your platform:

npm run package          # macOS
npm run package:win      # Windows
npm run package:linux    # Linux
npm run package:all      # all platforms

CLI Command

Register the logan command globally (one-time, after install):

npm link

Then open log files from any terminal:

logan myfile.log                # launch LOGAN with file
logan /path/to/other.log        # open in existing window if LOGAN is running
logan                           # launch LOGAN with no file

If LOGAN is already running, the file opens in the existing window. If not, a new instance launches with the file.

AI Agent Integration

LOGAN exposes a full log-analysis API that AI agents can use. Four integration paths:

Method	How
Claude Code (recommended)	Click "Launch Agent" → Setup Wizard auto-detects CLI and configures MCP
MCP clients (Cursor, Windsurf)	Tools auto-discovered via `.mcp.json` — just open the project
Custom scripts	Hit the HTTP API directly or use the `logan-listen` CLI helper
Built-in agent	Click "Launch Agent" → select "Built-in Agent" — no setup needed

Quick Start: Agent Setup Wizard

Open the Chat tab (bottom panel, chat icon)
Click Launch Agent (or the gear icon next to it)
The wizard auto-detects available tools (Claude Code CLI, etc.)
Choose your agent type and click Save & Launch

The wizard saves configuration to ~/.logan/agent-config.json. Subsequent launches skip the wizard.

See LOGAN-AGENT.md for the full API reference, example scripts, and integration guide.

Keyboard Shortcuts

Shortcut	Action
Ctrl+O	Open file
Ctrl+T	Open in new tab
Ctrl+W	Close tab
Ctrl+Tab / Ctrl+Shift+Tab	Next / previous tab
Ctrl+F	Focus search
F3 / Ctrl+G	Next match
Shift+F3	Previous match
Ctrl+B	Toggle bookmark
Ctrl+H	Highlight all occurrences of selection
Ctrl+Shift+H	Highlight first occurrence per line
Ctrl+Shift+S	Save selected lines to notes
F8 / Shift+F8	Jump to next / previous problem (fatal/error/warning)
PageDown / PageUp	Scroll one full page
Ctrl+D / Ctrl+U	Half page down / up (Mac-friendly)
Option+Down / Option+Up	Fast scroll (5 lines at a time)
Ctrl++ / Ctrl+- / Ctrl+0	Zoom in / out / reset
Ctrl+R	Reload current file from disk
Ctrl+1...5	Toggle sidebar panels (Folders / Bookmarks / Highlights / Stats / History)
Ctrl+6 / Ctrl+7	Toggle Overview / Time Gaps (bottom)
Ctrl+8	Toggle search configs
Ctrl+9	Toggle video player
Ctrl+\	Toggle panel visibility
Ctrl+`	Toggle terminal
Ctrl+Shift+N	Toggle notes drawer
Ctrl+Shift+R	Toggle search results
Alt+Z	Toggle word wrap
Esc	Close active panel/overlay

License

MIT

Name		Name	Last commit message	Last commit date
.github		.github
assets		assets
bin		bin
docs		docs
examples		examples
scripts		scripts
src		src
.cursorrules		.cursorrules
.gitignore		.gitignore
.mcp.json.example		.mcp.json.example
AGENTS.md		AGENTS.md
CLAUDE.md		CLAUDE.md
LICENSE		LICENSE
LOGAN-AGENT.md		LOGAN-AGENT.md
MANUAL.md		MANUAL.md
README.md		README.md
package-lock.json		package-lock.json
package.json		package.json
tsconfig.json		tsconfig.json
vitest.config.ts		vitest.config.ts

Navigation Menu

Repository files navigation

LOGAN - Log Analyzer

TL;DR

Features

Core Viewer

AI Agent Integration

Live Connections

Analysis & Filtering

Multi-file & Correlation

Decoding & Formats

Saved setup & portability

Annotations

Split & Diff

Media

Built-in Tools

Persistence

Requirements

Installing ripgrep

Installation

Download Pre-built Packages

Build from Source

CLI Command

AI Agent Integration

Quick Start: Agent Setup Wizard

Keyboard Shortcuts

License

About

Releases

Packages

Contributors

Languages

Latest commit

History

Folders and files

Repository files navigation

LOGAN - Log Analyzer

TL;DR

Features

Core Viewer

AI Agent Integration

Live Connections

Analysis & Filtering

Multi-file & Correlation

Decoding & Formats

Saved setup & portability

Annotations

Split & Diff

Media

Built-in Tools

Persistence

Requirements

Installing ripgrep

Installation

Download Pre-built Packages

Build from Source

CLI Command

AI Agent Integration

Quick Start: Agent Setup Wizard

Keyboard Shortcuts

License

About

Topics

Resources

Stars

Watchers

Forks

Releases

Packages

Contributors

Languages