.log file format
View, search, inspect, merge, and learn how log files are used for debugging, monitoring, server activity, app errors, audit trails, system events, and development workflows.
Also known as: Log Files
Format
.log
Original files stay unchanged. Tools download a new file when output is generated.
Every tool listed here works with .log files and runs in your browser. If the task you need is not here, the related formats below may cover it.
Open and inspect log files with search-friendly browser tools.
Merge log files chronologically or manually by arranging files before export.
Open, search, and inspect plain text files in your browser.
Merge plain text files in your chosen order with clean spacing between files.
Clean common OCR mistakes from copied scans and extracted document text.
A .log file is whatever the application writing it decided to emit. Some use a structured convention like the Common Log Format or line-delimited JSON; plenty use free-form text that changed between releases. Any tool that reads logs generically has to treat them as text first and infer structure second.
Comparing logs from two systems means reconciling their timestamps, and that is rarely trivial. One may write local time with no offset, another UTC with an ISO 8601 suffix, another epoch seconds. Add a daylight-saving transition and events can appear out of order or duplicated. Establish what timezone each file is in before drawing conclusions from the sequence.
Production logs rotate: renamed, compressed, and eventually deleted. The consequence is that the file you have often starts mid-incident, and the lines before the interesting error are in a different file. When you are reconstructing a timeline, merging the rotated files back into one chronological stream is usually the first step.
Up to a point — the file is read locally, so the limit is your device's memory. Multi-gigabyte logs are better split or filtered with a command-line tool first.
Merge them in chronological order and confirm that all files use the same timezone convention. Mixed local and UTC timestamps produce a timeline that looks plausible and is wrong.
Frequently — IP addresses, usernames, email addresses, session tokens, and full request URLs all commonly end up in logs. Treat a log file as sensitive until you have checked.