ULogViewer

See every log.
Spot every signal.

A cross-platform log viewer that supports reading, parsing, and analyzing various types of logs.

Available for
Installation and Upgrade Guide | View on GitHub
ULogViewer

πŸ“£ What's Changed in 2026.0 Preview

  • Support filtering log profiles in the Select log profile dialog.
  • Support temporarily showing raw log lines even when log patterns are defined.
  • Support filtering logs by multiple log levels.
  • Support editing visible log properties of the current non-built-in log profile in the log viewer.
  • Support importing application data from an existing ULogViewer instance.
  • Support using C# 14 as scripting language.
  • Improve user experience of the Select log profile dialog and log chart.
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πŸ“£ What's Changed in 4.1

  • Support setting text filter as exclusionary to filter logs without text matched by the pattern.
  • Support formatting CLEF data when reading raw logs through Standard output (stdout), File and HTTP.
  • Add CLEF Files built-in log profile.
  • Support specifying default log level in case of value of raw log level cannot be mapped or not presented.
  • Add Error, Exception and Warning log properties.
  • Allow specifying locale of time span/timestamp for log reading and writing.
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πŸ—„ Supported Log Data Sources

  • Standard Output (stdout)
  • Files
  • Windows Event Log Windows
  • Windows Event Log File
  • HTTP/HTTPS
  • TCP (without SSL)
  • UDP
  • SQLite Database
  • Azure CLI Pro
  • MySQL Database Pro
  • SQL Server Database Pro
  • Log Data Source Script Pro
  • Embedded log Data Source Script Pro

πŸ“– Log Profiles

Each log profile defines:
  • What log data source should be used.
  • How to parse log data into structured logs.
  • Which properties of the log should be displayed in the list.
  • Which properties of the log should be used to generate charts. Pro
  • How to output logs back to text (e.g., copying).
Currently there are 41 built-in log profiles:
  • Android Device Event Log
  • Android Device Log
  • Android Device System Trace macOSLinux
  • Android Log Files
  • Android Kernel Log Files
  • Android Process Memory Monitor Template
  • Android System Memory Monitor
  • Android System Trace File
  • Apache Access Log Files
  • Apache Error Log Files
  • Apple Devices Log
  • Apple Device Simulators Log macOS
  • Azure Webapp log Files Pro
  • Azure Webapp Log Stream ProTemplate
  • CLEF Files Prov4.1+
  • Git Log
  • Git Log (Simple)
  • Linux Kernel Log Linux
  • Linux Kernel Log Files
  • Linux Real-time System Wide Log Linux
  • Linux System Log Linux
  • Linux System Log Files
  • macOS Installation Log macOS
  • macOS Real-time System Wide Log macOS
  • macOS System Log Files
  • NLog (TCP)
  • Raw Text In Files
  • Raw HTTP/HTTPS Response
  • Raw Text From Standard Output (stdout) v4.0+
  • Raw Text From TCP Client
  • Specific Android Device System Trace Templatev4.0+
  • Specific Apple Device Log Template
  • Specific Apple Device Simulator Log Template
  • ULogViewer Log File
  • ULogViewer Real-time Log
  • Windows Event Log Files
  • Windows Event Logs Template
  • Windows Event Logs (Application) Windows
  • Windows Event Logs (System) Windows
  • Windows Event Logs (Security) Windows
  • Windows Event Logs (Setup) Windows
You can also create, copy or export your own log profiles according to your requirement.

Video Tutorial (Please open subtitles)

Create a simple log profile based on a log file:

πŸ” Log Filtering

Log filtering is one of the most important features in ULogViewer that helps you find and analyze problems from logs. You can filter logs by:
  • Text filter defined by a regular expression.
  • Level (Priority) of the log.
  • Process ID of the log, if available.
  • Thread ID of the log, if available.
  • Marked logs.
For text filter, you can also predefine some filters you may use frequently and filter logs by combination of these text filters.
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πŸ“Œ Log Marking

When viewing logs, you can mark some logs with different colors which are important for you. There is a separated side panel to list all marked logs to help you to jump to marked log quickly. Marked logs will be kept if you are viewing logs from files so that you don’t need to mark them again when you open log files next time.

πŸ“Š Log Analysis

Except for log filtering, you can also define rule sets or write scripts to analyze logs. Log analysis runs in the background separately and generates results to a separate side panel. Currently there are 4 types of log analysis supported:
  • Key Log Analysis
    Find logs with a specific text pattern and level. You can extract information from the log and put it in the result message.
  • Operation Duration Analysis
    Find operations marked by specific starting and ending logs and calculate their duration. You can extract information from the log and put it in the result message.
  • Operation Counting Analysis
    Find operations marked with a specific text pattern and level, then count the number of operations that occurred for each given time frame. You can extract information from the log and put it in the result message.
  • Log Analysis ScriptPro
    Write script to analyze logs according to your requirement completely.
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πŸ“” See Also