Show HN: Lightweight log viewer with Python-powered filtering and formatting

I'd like to share "klp", a command-line log viewer for investigating small to medium-sized log files (up to ~100k lines). While there are faster and more mature log viewers out there, I think klp has some features that might be interesting:

- Visualize log level patterns with --levelmap showing the density of different log levels over time (e.g., IIIWWEEE for a sequence of INFO, WARNING, ERROR)

- Visual separation of time gaps with --mark-gaps INTERVAL (e.g., 1h) to spot suspicious quiet periods

- Condense bursts of events with --fuse INTERVAL (e.g., 1h) to highlight when activity starts and ends

- Built-in regexes for common patterns (URLs, IPs, file paths, email addresses, common error messages, and many others)

- Python expressions for complex filtering: --where "int(status) >= 500 and 'timeout' in message.lower()"

- Built-in support for logfmt, JSON Lines, CSV, SQLite and others, plus ability to write ad-hoc parsers in Python on the command line

- Custom output formatting using Python code and templates

klp is a single Python file with no dependencies beyond Python 3.7+. Install with pip install klp-logviewer or download the file from GitHub:

<https://github.com/dloss/klp>

I originally built this for my own debugging needs at work where I couldn't install other tools. When my employer allowed me to open-source it (MIT license), I added more features to explore ideas I hadn't seen in other log tools.

Since I'm just a single developer maintaining this in my spare time, I've included a carefully curated list of more robust alternatives in the README.

I welcome your feedback on klp and its features, and would be delighted if these ideas inspire other log tools - especially approaches like visual time gaps, fusing events and log level maps.