Error Log Cleaner

Filter out noise and extract only the ERROR or EXCEPTION lines.

Cut a noisy log down to the lines that matter

A busy application can write thousands of INFO and DEBUG lines around the one that explains an outage. The Error Log Cleaner scans pasted text line by line and returns only the entries that look like failures, so you can read, share or attach them to a ticket without scrolling through the rest.

How to use it

Paste your log into the Input Data box. Press Sample to load a five-line example, or Clear to reset the field.
Click Process Now.
Read the filtered lines in the results panel, together with the counts Total Scanned and Errors Found.
Use Copy to put the lines on your clipboard or Download to save them as result.txt.

If the box is empty you will be asked to enter logs. If nothing matches, a green message tells you that no errors were found and how many lines were checked.

What counts as an error line

A line is kept when, ignoring case, it contains any of these words: ERROR, FATAL, EXCEPTION or FAIL. Because the test is a substring search, it also catches words such as errors, failed, failure and NullPointerException, and it does not care whether the word is a level tag or part of a message. Blank lines are skipped and are not counted in the total. Lines are output exactly as pasted, without any reformatting.

Everyday uses

Pulling failure lines out of a CI build log before pasting them into a bug report.
Scanning a copied section of a web server or application log after an incident.
Making a quick summary of what went wrong overnight in a scheduled job.
Trimming a log so it fits within a chat message or a support form.

Limitations to be aware of

Only single lines are matched. A multi-line stack trace will lose every continuation line that does not itself contain one of the keywords, such as the indented at ... entries, so use the Stack Trace Formatter for those. False positives are possible: a line that says no errors occurred, or a request path containing the word fail, will be kept. Lines using other level names, for example CRITICAL or SEVERE, are ignored unless they also contain a matching word. The filtering runs in your browser using the text you paste, with no file upload step.

Related Tools

Frequently Asked Questions

Which words does the cleaner look for?

It keeps any non-empty line containing ERROR, FATAL, EXCEPTION or FAIL, in any letter case. Since it is a substring match, words like failed, errors and NullPointerException also match. Other level names such as CRITICAL are not searched for.

Why are some lines from my stack trace missing?

The filter checks each line on its own. Indented at lines in a trace usually contain no keyword, so they are dropped. Paste the trace into the Stack Trace Formatter instead to keep and highlight every line.

Can it produce false matches?

Yes. A message such as no errors found or a URL containing the word fail will match. The tool cannot judge context, so scan the extracted lines and ignore the ones that are not real problems.

What are the two counts shown?

Total Scanned is the number of non-empty lines in your input, and Errors Found is how many of those matched. Comparing them gives a rough sense of how noisy the log was.

What format is the download?

The Download button saves the extracted lines as a plain text file called result.txt. If the result panel shows the no-errors message instead of lines, that message is what will be saved.