The file is read in pieces on your device. Nothing is uploaded, so private logs stay private. Open a large log file, filter by level and time, search it and jump from error to error. It is free and runs in your browser.
How to read a log file
- Press Open a log file, or press Try an example. Press Stop if a very large file takes too long.
- Choose which levels to show under Show these lines.
- Type in Find to search. Use From and To to limit the time range, or Any time to remove the limit.
- Use Previous error and Next error to step through problems.
- Use Go to line to jump to a line number.
- Press Download shown lines to save what you filtered.
Built for big files
The file is streamed rather than loaded in one go, so lines appear while it reads, and only the lines on screen are drawn. Gzipped logs (.gz) are unpacked as they stream. Files with a few million lines work well on a typical laptop; the limit is your device's memory.
Levels and times
Levels are read from common formats: ERROR, WARN, INFO and DEBUG words, [error] tags, level=warn fields, JSON logs with a level field, numeric levels from JSON loggers, Android logcat letters and Python tracebacks. Stack trace lines take the level of the line above. Timestamps are read from ISO 8601, Apache and Nginx access logs, syslog and JSON time fields.
Tips for finding the problem
- Start by showing only errors, then widen to warnings around the time of the failure.
- Use the time filter to narrow down to the minutes when the problem happened.
- Search for an ID, such as a user or request number, to follow one thing through the log.
- Hide noisy lines such as health checks so the real messages stand out.
- Save the filtered lines to share with a teammate or support, after removing private details.
Who uses it
Developers, system administrators and website owners checking why something broke, and support staff reading logs from customers. For timing jobs, see the cron expression tool, and to compare two logs, the diff checker.
Questions
How do I find every error quickly?
Turn on only the Error and Fatal levels, or keep everything visible and use Next error to step through them in context. Click any line to see it in full below the list.
Can I search with a regular expression?
Yes. Turn on Regular expression and type a pattern such as user=\d+ or (timeout|refused). Hide matching lines turns the search around, which is handy for removing noise like health checks.
How does the time filter treat time zones?
Timestamps with a zone, like Z or +02:00, are exact. Timestamps without one are read in your local time zone, or in UTC if you turn that option on, and the From and To boxes use the same choice.
Can I save what I filtered?
Download shown lines saves exactly the lines that match your filters as a .log file.