Log Viewer

What it's for

Find what matters in a log file. Application, server and system logs run to thousands of lines; this shows them as entries you can narrow down by level, text and time, with a stack trace or other multi-line message kept with the line it belongs to.

For example, when a customer sends a 50 MB application log and says it failed “around ten past nine”, open it here, untick everything but errors and warnings, and set the times either side.

How to use it

Choose a log file or drop it on the page (or paste lines under Or paste lines). Levels are recognised from words such as ERROR, WARN and INFO near the start of a line, from JSON logs’ level field and from syslog priorities; each level gets a box with its count. Times are read from ISO dates, Apache and nginx access logs, syslog and JSON time fields.

• Contains keeps entries with that text, or matching a regular expression written as /pattern/flags.
• From and To keep entries in that time range.
• Show each entry’s time in my time zone adds a column of times converted from the zone the log gives (the choice is remembered).

Entries with more lines fold open. Copy these and Save these take every entry that passes the filters.

Example

Under Or paste lines, paste these and press Show:

2026-10-06 09:00:01,123 INFO  Starting app
2026-10-06 09:00:02,500 WARN  Disk at 91%
2026-10-06 09:00:03,000 ERROR Request failed
java.lang.IllegalStateException: boom
	at com.example.Foo.bar(Foo.java:12)
2026-10-06T09:00:04Z DEBUG done

The message says 4 of 4 entries (6 lines). The error keeps its two lines of stack trace. Untick Info and type /disk|fail/i under Contains, and 2 entries are left: the warning and the error.

Good to know

Up to 2,000 entries are shown at once, though Copy and Save include them all. Very large files are limited by the browser’s memory. A time without a zone is read as this device’s time, and syslog lines without a year as this year. Logs whose entries don’t start with a time are grouped only by indented and stack trace lines.