Log Analyzer
Analyze and filter application logs. Find errors and warnings quickly.
Input Logs
No Logs Yet
Paste your log content in the text area above, upload a log file, or load an example to get started.
What is Log Analysis?
Log analysis is the process of reviewing application logs to understand what your software is doing, identify errors, and diagnose issues. Logs are chronological records of events that occur during application execution.
Why Logs Are Important
- Debugging: Identify the root cause of errors and exceptions
- Monitoring: Track application health and performance
- Auditing: Record user actions and system events
- Troubleshooting: Investigate production issues without access to debuggers
Common Log Levels
How to Use the Log Analyzer
- Input Your Logs: Paste log content into the text area or upload a .log or .txt file
- Review Summary: Check the summary panel showing total lines and counts by log level
- Filter by Level: Click filter buttons to show only errors, warnings, info, or debug logs
- Search Logs: Use the search box to find specific text. Matches are highlighted in yellow
- Export Results: Copy filtered logs to clipboard or download them as a text file
Tip: Start by filtering to show only errors and warnings to quickly identify critical issues.
Reading Log Levels
ERROR / FATAL
Critical issues requiring immediate attention. Application functionality is broken or severely impaired.
ERROR: Failed to connect to database
FATAL: Application startup failed
WARN / WARNING
Potential problems or unexpected situations. Application continues running but behavior may be degraded.
WARN: Retrying connection (attempt 2/3)
WARNING: Deprecated API usage detected
INFO
Normal application events marking important milestones. Used to track application flow.
INFO: Application starting
INFO: Configuration loaded successfully
DEBUG / TRACE
Detailed diagnostic information for development. Helps understand what the code is doing step-by-step.
DEBUG: Loading config from /etc/app
TRACE: Entering method processData()
Common Log Patterns
Stack Traces
Multi-line error details showing the call stack. Look for the first line to identify the error type, then trace backwards to find where in your code the error originated.
at Database.connect(/app/db.js:45)
at Application.init(/app/index.js:23)
Connection Errors
Failed network or database connections. Check network availability, firewall rules, and connection strings.
ERROR: ECONNREFUSED localhost:5432
Memory Issues
Out of memory errors indicate the application needs more heap space or has a memory leak.
ERROR: Cannot allocate memory
Authentication Failures
Failed login attempts or invalid credentials. Check authentication configuration and user permissions.
ERROR: Invalid token or expired session
Debugging Best Practices
📍 Read Systematically
Don't jump randomly through logs. Read chronologically to understand the sequence of events leading to an error.
🎯 Focus on Errors First
Filter to show only errors and warnings. These indicate problems that need attention before looking at info logs.
⏰ Check Timestamps
Pay attention to when errors occur. Multiple errors at the same time might indicate a single root cause.
🔄 Look for Patterns
Repeated errors might indicate a loop or retry mechanism. Understanding patterns helps identify systemic issues.
🔍 Use Search Effectively
Search for specific error messages, user IDs, or request IDs to trace a particular issue through the logs.
📝 Correlate with Code
Match log messages with your source code. File names and line numbers in stack traces point to problematic code.