Log File Analyzer

The Log File Analyzer is a 100% client-side tool that parses, categorizes, and visualizes log files directly in your browser. It automatically detects log formats (Apache, Nginx, Syslog, application logs, JSON), categorizes entries by severity level, identifies errors and stack traces, detects security threats, and provides insights through interactive charts—all without uploading any data to external servers.

Our tool supports a wide range of log formats: Apache Combined/Common, Nginx, Syslog, IIS, JSON logs, and general Application logs (with timestamp + level + message structure). You can also define custom regex patterns for proprietary log formats using named capture groups.

The tool samples the first 100 lines of your log file and tests them against predefined regex patterns for known formats. If more than 50% of lines match a specific format pattern, that format is selected. For JSON logs, it attempts to parse each line as JSON. If no format matches, it falls back to a general application log parser that looks for common timestamp and level patterns.

Our security analyzer uses rule-based pattern matching to detect: SQL Injection attempts (UNION SELECT, OR 1=1, etc.), Path Traversal attacks (../, %2e%2e), XSS patterns (<script>, javascript:, onerror handlers), Brute Force attempts (multiple failed logins from same IP), and Suspicious IP activity (IPs with high error rates). Each threat is categorized by severity level.

The error analyzer groups similar error messages together by hashing the first 100 characters, counts occurrences to identify the most frequent errors, and detects stack traces using patterns like "at function()" or "Traceback". This helps you prioritize fixes by focusing on errors that occur most frequently rather than one-off issues.

Yes! For files larger than 50MB, our tool uses streaming/chunked processing to read the file in 1MB chunks, preventing browser memory crashes. You'll see a progress indicator showing lines processed, data size, and elapsed time. There's no strict limit—the actual maximum depends on your browser and device memory.

If your logs contain response time data (e.g., "200ms", "1.5s"), the Performance tab displays: Average response time, Minimum/Maximum times, 95th percentile (P95), Slowest requests list, Throughput (requests/second), and Error rate over time. This helps identify performance bottlenecks and slow endpoints.

Our rule-based anomaly detection looks for: Error spikes (when errors per hour exceed 3x the average), Log gaps (periods longer than 10 minutes with no entries, indicating potential downtime), and Unusual patterns like sudden traffic changes. You can adjust the sensitivity in Settings to catch more or fewer anomalies.

Yes! The Advanced Search tab supports regex patterns, case-sensitive search, and whole-word matching. We also provide quick-search buttons for common patterns like IP addresses, SQL queries, authentication events, and server errors—no regex knowledge required.

You can export your analysis in multiple formats: CSV (spreadsheet-compatible data), JSON (structured analysis with all metrics), and PDF (printable report summary). The export includes log entries, error summaries, security findings, and performance metrics based on your current filters.

100% Private. All log parsing and analysis happens entirely in your browser using JavaScript. Your log files, IP addresses, error messages, and any sensitive data are never uploaded to any server. This makes the tool safe for analyzing production logs, security-sensitive data, and confidential system information.