Drop a log file or livestream one. Search it in seconds. Keep it fully offline. Let your AI agent query it.
LogSonic is a local-first log analytics app for Windows, Mac, and Linux. One self-contained binary serves a fast browser UI, auto-detects log formats, indexes everything for full-text search, and ships an MCP server so Claude, Cursor, Windsurf, or any MCP client can query your local logs. No telemetry. No cloud. No network calls.
Stream logs into LogSonic while the browser is open. logsonic tail can follow a server-side file or read stdin, publish rows to the UI in real time, keep indexing in the background, and let you pause/resume the browser feed without stopping ingestion.
tail -f /var/log/app.log | logsonic tail - --source app
logsonic tail -f /var/log/app.log --source appRows are searchable immediately, including rows skipped while the browser feed was paused. See Live Streaming or run the combined import + Livestream demo:
node demo/combined-demo.mjsInstall on macOS with Homebrew:
brew tap logsonic/logsonic
brew install logsonic
logsonicOr download a pre-built binary from GitHub Releases, then open:
http://localhost:8080
For Linux, Windows, Docker, source builds, storage locations, and the macOS app behavior, see Installation.
- Engineers who cannot send logs to cloud tools.
- AI-native developers who want local logs available to MCP clients.
- Backend and SRE teams debugging large log dumps without standing up ELK.
| LogSonic | lnav | Logdy | GoAccess | Datadog/ELK | |
|---|---|---|---|---|---|
| Fully offline / local-first | yes | yes | yes | yes | no |
| Browser GUI | yes | terminal | yes | HTML report | yes |
| Auto-detect log formats | yes | partial | no | web logs only | yes |
| AI agent access (MCP) | yes | no | no | no | partial |
| Indexed full-text search | yes | yes | no | no | yes |
| Single binary, no deps | yes | yes | yes | yes | no |
| Live tail / streaming | yes | yes | yes | yes | yes |
- Format detection with log2grok, including custom saved Grok patterns.
- Multi-file import with per-file format confirmation.
- Smart timestamp resolution for logs with missing years, timezones, or dates.
- Bleve-backed full-text search with field shorthand, regex, exclusions, and boolean operators.
- Live tailing from stdin or server-side files.
- MCP server for AI clients.
- Color rules, event histogram, source filters, and dark/light themes.
- Local file-based storage with retention controls.
- Installation: Homebrew, app bundle, binaries, Docker, source builds, and storage paths.
- Configuration: command flags, environment variables, CLI subcommands, and examples.
- Getting Started: importing logs, searching, and MCP setup links.
- Live Streaming:
logsonic tail, stdin streaming, server-side file following, and demos. - Timestamp Resolution: how LogSonic derives real timestamps and when to override.
- Development: local backend/frontend setup, tests, E2E, and Swagger generation.
- Architecture: backend, frontend, storage, and MCP architecture.
- MCP Setup: configure Claude Desktop, Cursor, Windsurf, or another MCP client.
- Agent Playbook: query patterns and workflow guidance for AI clients.
How does LogSonic handle large log files?
It indexes logs with Bleve and stores local file-based indices for fast search over large datasets.
Can I use custom log formats?
Yes. Paste a Grok pattern during import or save custom patterns for reuse.
Is my data sent to any servers?
No. LogSonic runs locally and keeps data on your machine.
For issues, feature requests, or questions, open an issue on the GitHub repository.
LogSonic is released under the MIT License.