Which log viewer should you use on a Mac?

A Mac already has two ways to read a log: Console and the Terminal. Whether you need anything else depends on the file. A small log opens anywhere; a log of several gigabytes, one that is still being written, or one full of terminal colour codes is where the tools start to differ. We make Log Viewer, so it is in this list, but each option below is described from its own documentation and the table says where others are the better pick.

Console: the system log, and simple searches

Console is built for the Mac's own unified log. It streams messages live from your Mac or a connected device and opens .logarchive bundles with sorting and time filters. It also lists the text logs under Log Reports and lets you search inside one. What Apple does not document is the rest of a log reader's job for arbitrary files: regular-expression filtering, colour codes or comparing two logs.

less and tail -f: always there

less opens files of any size quickly because it reads from disk as you scroll. Inside it, &pattern shows only matching lines, F follows new lines like tail -f, and less -R shows ANSI colours. The limits are the ones of a terminal: one file per view, and commands to remember rather than controls to click.

less -R +F /var/log/app.log

BBEdit: a text editor that copes with big files

BBEdit keeps working in a free mode after its 30-day trial, and Bare Bones says large files present no intrinsic problem, though some operations may be limited above 2 GB. Its grep search and multi-file search are strong. It is an editor rather than a log viewer, so a live follow mode and colour-code rendering are not part of its documented features; Git integration needs the paid licence.

VS Code: fine for small logs

VS Code highlights .log files out of the box. Above 20 MB or 300,000 lines it turns off tokenization, wrapping, folding and several other features to avoid freezing, and above 50 MB extensions no longer see the file at all, so log-highlighting extensions stop helping exactly when a log gets big.

lnav: the power tool for the terminal

lnav detects common log formats, merges several files into one timeline, follows files as they grow, filters with regular expressions and even lets you query logs with SQL. If you live in the terminal and handle server logs daily, it is hard to beat. It is keyboard driven with no graphical interface. Install it with Homebrew: brew install lnav.

klogg: a fast open-source GUI, with caveats

klogg reads huge files from disk rather than memory, searches with AND, OR and NOT, and reloads a file when it changes. Its last stable release is from June 2022 and that Mac build is for Intel processors, so an Apple silicon Mac needs Rosetta to run it.

Log Viewer: a Mac app for the whole job

Log Viewer memory-maps files so a multi-gigabyte log opens straight away, filters to matching lines and exports them, follows a file through rotation and truncation, renders ANSI colours, compares two logs side by side and can redact secrets before you share one. It is free on the Mac App Store with no in-app purchases. It is a viewer, not an editor, and it does not query logs with SQL the way lnav does.

Which one to choose

• The Mac's own system log: Console.
• A quick look at a file in a terminal session: less, with -R for colours.
• Heavy, repeated server log analysis from the terminal: lnav.
• Editing the file as well as reading it: BBEdit.
• Opening, filtering and following big log files in a Mac window: Log Viewer.