Log Pattern Analyzer - Free Online Tool

Log Content

Paste multi-line log content. The analyzer detects timestamps, log levels, and extracts metadata automatically.

Analysis Results

What is the Log Pattern Analyzer?

The Log Pattern Analyzer detects patterns in log content by grouping similar lines, counting frequent errors, identifying log levels (error, warn, info, debug), and extracting metadata like IP addresses, HTTP status codes, URL paths, and user agent strings. It works with any text-based log format including Apache, Nginx, syslog, and application logs.

How to Use

Paste your log content into the input area
The analysis runs automatically as you type (with debounce)
Review results in grouped sections: Levels, Groups, Errors, and Metadata
Use the Export button to download a full report

Use Cases

Incident investigation — Quickly identify the most frequent errors and their first occurrence
Access log analysis — Extract unique IPs, request paths, and status codes from web server logs
Pattern discovery — Group similar log lines to find recurring issues hidden in noise
Level breakdown — See the distribution of error, warn, info, and debug messages at a glance
Bot detection — Extract user agent strings to identify crawlers and automated clients

Example: Analyzing an Apache Access Log

Given a sample Apache access log:

192.168.1.50 - - [15/Jan/2024:10:24:01 +0000] "GET /api/users HTTP/1.1" 200 1234 "-" "Mozilla/5.0"
10.0.0.1 - - [15/Jan/2024:10:24:02 +0000] "POST /api/login HTTP/1.1" 401 89 "-" "curl/7.88"
192.168.1.50 - - [15/Jan/2024:10:24:03 +0000] "GET /api/users/1 HTTP/1.1" 404 Not Found

The analyzer extracts IPs (192.168.1.50, 10.0.0.1), identifies paths (/api/users, /api/login, /api/users/1), detects status codes (200, 401, 404), and recognizes the Apache/CLF timestamp format.

Supported Timestamp Formats

ISO 8601 — 2024-01-15T10:23:45.123Z
Apache/CLF — 15/Jan/2024:10:24:01 +0000
Syslog — Jan 15 10:23:45
Date-time — 2024-01-15 10:23:45
Unix epoch — 1705312345

Line Grouping Algorithm

Similar lines are grouped by normalizing variable parts — timestamps become <TIMESTAMP>, IPs become <IP>, UUIDs become <UUID>, and numbers become <N>. This reveals recurring patterns that differ only in their dynamic values.

Privacy and Security

All analysis happens entirely in your browser using JavaScript. Your log content is never transmitted to any server. No data is stored, logged, or shared. For large inputs (over 200KB), processing automatically offloads to a Web Worker to keep the page responsive.

Frequently Asked Questions

What does the Log Pattern Analyzer do?

The Log Pattern Analyzer detects patterns in log content: it identifies timestamps, groups similar lines, counts frequent errors, detects log levels (error, warn, info, debug), and extracts metadata like IP addresses, HTTP status codes, URL paths, and user agent strings.

What log formats are supported?

The analyzer works with any text-based log format. It recognizes timestamps in ISO 8601, Apache/CLF, syslog, and Unix epoch formats. Log levels are detected from common markers like ERROR, WARN, INFO, DEBUG, FATAL, and CRITICAL regardless of case.

How does line grouping work?

Similar lines are grouped by normalizing variable parts (timestamps, IPs, UUIDs, and numbers) into placeholders. This reveals recurring patterns — for example, repeated error messages that differ only in their request ID or timestamp are grouped together.

What metadata is extracted from logs?

The tool extracts IPv4 and IPv6 addresses, HTTP status codes (when found in HTTP-related context), URL paths from HTTP methods (GET /path, POST /path, etc.), and user agent strings (Mozilla, curl, Python, and other common clients).

What are the input size limits?

The tool warns at 1MB and rejects input above 10MB. For large inputs over 200KB, processing is automatically offloaded to a background thread (Web Worker) to keep the page responsive.

Can I analyze Apache or Nginx access logs?

Yes. The analyzer handles Apache Combined/Common Log Format and Nginx access logs natively. It extracts IPs, request paths, status codes, and user agents from these formats automatically.

Is my log data sent to a server?

No. All analysis happens entirely in your browser. Your log content never leaves your device. No data is stored, logged, or transmitted.