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A Kookaburra sitting on a scroll



A terminal application to view, tail, merge, and search log files (plus JSONL).

🎬 Viewing a single file

Keep calm and log files

See Toolong on for a calming introduction to Toolong.


Screenshot 2024-02-08 at 13 47 28
  • Live tailing of log files.
  • Syntax highlights common web server log formats.
  • As fast to open a multiple-gigabyte file as it is to open a tiny text file.
  • Support for JSONL files: lines are pretty printed.
  • Opens .bz and .bz2 files automatically.
  • Merges log files by auto detecting timestamps.


I spent a lot of time in my past life as a web developer working with logs, typically on web servers via ssh. I would use a variety of tools, but my goto method of analyzing logs was directly on the server with *nix tools like as tail, less, and grep etc. As useful as these tools are, they are not without friction.

I built toolong to be the tool I would have wanted back then. It is snappy, straightforward to use, and does a lot of the grunt work for you.


Screenshot 2024-02-08 at 13 47 28 Screenshot 2024-02-08 at 13 48 04
Screenshot 2024-02-08 at 13 49 22 Screenshot 2024-02-08 at 13 50 04


🎬 Merging multiple (compressed) files
🎬 Viewing JSONL files
🎬 Live Tailing a file


Toolong is currently best installed with pipx.

pipx install toolong

You could also install Toolong with Pip:

pip install toolong


If you use pip, you should ideally create a virtual environment to avoid potential dependancy conflicts.

However you install Toolong, the tl command will be added to your path:


In the near future there will be more install methods, and hopefully your favorite package manager.


Toolong works on Linux, macOS, and Windows.

Opening files

To open a file with Toolong, add the file name(s) as arguments to the command:

tl mylogfile.log

If you add multiple filenames, they will open in tabs.

Add the --merge switch to open multiple files and combine them in to a single view:

tl access.log* --merge

In the app, press f1 for additional help.


In addition to specifying files, you can also pipe directly into tl. This means that you can tail data that comes from another process, and not neccesarily a file. Here's an example of piping output from the tree command in to Toolong:

tree / | tl


This guy. An ex web developer who somehow makes a living writing terminal apps.


If you follow me on Twitter, you may have seen me refer to this app as Tailless, because it was intended to be a replacement for a tail + less combo. I settled on the name "Toolong" because it is a bit more apt, and still had the same initials.


Toolong v1.0.0 has a solid feature set, which covers most of my requirements. However, there is a tonne of features which could be added to something like this, and I will likely implement some of them in the future.

If you want to talk about Toolong, find me on the Textualize Discord Server.


I am grateful for the LogMerger project which I referenced (and borrowed regexes from) when building Toolong.


Toolong is not the first TUI for working with log files. See lnav as a more mature alternative.