INFO live log viewer · macOS · Windows · Linux
Like tail -f with a window around it. Five million lines open in 25 milliseconds, a level filter answers in 15, and a stack trace stays in one piece.
Free and open source (MIT). No account, no telemetry.
Try it: click a level, Alt-click for only that level, type in the search, freeze.Simulated in your browser. The real one reads real files.
DEBUG took 25ms
The Rust backend keeps 16 bytes per line in memory and leaves the rest on disk. That is why half a gigabyte feels like a small file.
500 MB, 5.1 million lines, Apple Silicon, release build. All measurements
INFO seven ways to find it
ERROR levels
TRACE to FATAL, with chips that count while the file grows. Continuation lines inherit the level of their entry, so a filter never tears an exception apart.
A recognised format becomes a table with one column per field: time, level, thread, logger, message.
WARN filter tree
Text or regex, levels, a field, a time span, a section between two markers. A request id in the head and “Timeout” in its stack trace match together.
Mark text and press a key to filter on it, or to exclude it.
INFO filter tabs
A filter opens as a tab of its own and filters further: app.log › ERROR › OrderService › 4711. Change a filter above and every tab below follows live.
FATAL timeline
A strip above the log stacks the entries of the whole file over time. Peaks and bursts of errors stand out, a silence is hatched: “no entries 10:04–10:51”.
Click to jump there, drag a window and make it a filter.
ERROR overview ruler
The bar right of the log shows where errors and warnings lie, as density and not as one solid colour. Bookmarks are flags, notes are diamonds.
This page has one too. Look right.
DEBUG detail panel
Head line and stack trace without the cut at the screen edge. Embedded JSON or XML is indented and coloured by its own tokenizer, so 64-bit ids stay exact.
INFO dashboard
Errors per minute, the error rate, took as mean and maximum. Panels start from templates and show their SQL to change. Click a bar to land on its first line.
INFO and the rest of the toolbox
Measurements in the text become columns of their own. The app suggests them on opening; units are converted, so took > 500 ms also finds 1.2s.
Up to 16 logs in one tab, sorted by timestamp, each with a colour stripe. New lines keep coming in live.
Stay at the end while you are there, scroll up and it pauses. Freeze holds a tab still while filters and search keep working.
Filter or highlight, regular expressions, case, jump between matches. Full text over 5 million lines in 0.7 s.
The selection, the view or the whole file. Written by the backend in the background: 500 MB as text in half a second.
One key sets a flag in the gutter and on the ruler, another jumps to the next. They survive in a workspace.
Files, merges, every filter tab, bookmarks, notes and layout in one file. Paths are kept relative too, so a folder with logs can be shared.
Put a note on an entry, then copy lines with file, time span and filter as Markdown or Jira markup for the ticket.
WARN not every log is a file
Every source without a file writes into a spool on disk, and the app tails that like any log. So filters, timeline, dashboard, export and merge work for all of them.
FATAL OutOfMemory, explained
Over the Model Context Protocol, Claude Code, Claude Desktop or Cursor see your tabs and use the app’s engines instead of reading whole files. The answer shows up in the window: a filter tab, a note, the line scrolled into view.
Off by default. No port while it is off. Opening files and exporting ask you first.
31 tools, three tiers, the safety modelWhat went wrong in app.log in the last 30 minutes?
get_timeline 1 outage, 1 burst of errors at 10:07
run_sql errors by logger since 09:40
open_filter_tab app.log › ERROR › ConnectionPool
add_note line 4,538 “KI: first exhausted pool”
The connection pool ran out at 10:07:33. 450 errors follow, all from OrderService.place. I opened a tab with them and left a note on the first one.
DEBUG theme = …
From One Dark to Solarized Light to a C64. The window frame follows, and “follow system” takes a light and a dark one of your choice.
INFO started on 3 platforms
One app, built with Tauri, Rust and Angular. The automated tests run on all three systems.
Apple Silicon and Intel in one universal app.
.dmgReads the Windows event logs too, of this computer or another one.
installer · .msiFor desktops with WebKitGTK.
.deb · AppImage$ log-commander /var/log/app.log
Free and open source under the MIT license. The packages are not signed yet.
