A fast, AI-ready log file viewer built with Electron. Handles 14 million+ lines with virtual scrolling, integrates with AI agents via MCP, connects to live serial/logcat/SSH streams, and provides deep analysis tools — all in one desktop app.
- Virtual scrolling — Constant memory usage and smooth 60fps, even with multi-million line files
- 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
- Word wrap & zoom — Toggle wrapping, adjust font size with Ctrl+/- or mouse wheel
- Column visibility — Auto-detect delimited columns and show/hide them
- JSON auto-format — Pretty-print JSON files on open
- MCP support — 30+ 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
- 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
- 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
- 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 (Ctrl+8)
- 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.txtfiles
- 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
- Video sync — Open a screen recording alongside logs, set a sync point, click lines to seek video (Ctrl+9)
- Image viewer — View PNG, JPG, SVG images with zoom in the bottom panel
- 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)
- 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
- Node.js 18+
- ripgrep (optional, recommended for fast search)
macOS:
brew install ripgrepUbuntu/Debian:
sudo apt install ripgrepWindows:
choco install ripgrepArch Linux:
sudo pacman -S ripgrepIf ripgrep is not installed, LOGAN falls back to a stream-based search.
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 |
git clone https://github.com/SolidKeyAB/logan.git
cd logan
npm install
npm start # builds and launches LOGANTo 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 platformsRegister the logan command globally (one-time, after install):
npm linkThen 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 fileIf LOGAN is already running, the file opens in the existing window. If not, a new instance launches with the file.
LOGAN exposes a full log-analysis API that AI agents can use. Three integration paths:
| Method | How |
|---|---|
| MCP clients (Claude Code, Cursor) | 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" in the Chat tab — no setup needed |
See LOGAN-AGENT.md for the full API reference, example scripts, and integration guide.
| 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 |
| 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+1...7 | Toggle panels (Folders/Stats/Analysis/Gaps/Bookmarks/Highlights/History) |
| 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 |
MIT
