How to Read Log Files Faster with Search and Level Filters

Log files are the diary of software systems. They record what happened, when it happened, and often why. But reading raw logs is tedious — especially when you are looking for a specific error among thousands of lines. Filelume parses log files in your browser and turns them into filterable event streams.

Why logs are hard to read

A typical log file is a long sequence of timestamped messages:

2026-07-24 10:23:15 INFO  Application started
2026-07-24 10:23:16 DEBUG Loading configuration from /etc/app/config.yaml
2026-07-24 10:23:17 WARN  Deprecated option 'legacy_mode' found
2026-07-24 10:23:18 ERROR Failed to connect to database: connection refused
2026-07-24 10:23:19 INFO  Retrying connection (attempt 1/3)
2026-07-24 10:23:20 INFO  Database connection established

Finding every ERROR in a 10,000-line log file by hand is impractical. Filelume parses the log, extracts levels and timestamps, and lets you filter instantly.

How Filelume parses logs

Filelume supports multiple log formats:

JSONL/NDJSON: Each line is a JSON object with structured fields.
Timestamp-level-message: The most common format — a timestamp followed by a level and message.
Syslog-style: Standard syslog format with facility and severity.
Web access log: Apache/Nginx access logs with request details.
Stack-trace continuation: Multi-line entries where stack traces follow error messages.
Generic raw line: When no pattern is detected, each line is treated as a raw event.

The parser automatically detects the format and shows a confidence score. You can override the parser if the detection is wrong.

Filtering and search

Once parsed, you can:

Filter by level: Show only ERROR and WARN, or any combination.
Search full text: Find any string across all events.
Time range: Focus on a specific time window.
Source: Filter by the component or module that logged the event.
HTTP status: For web logs, filter by response status code.

Timeline and statistics

Filelume shows a timeline visualization and summary statistics:

Total events parsed
Events per level (INFO, WARN, ERROR, etc.)
Time range covered
Parse confidence percentage
Unparsed line count

Exporting log data

Filelume can export filtered log data:

Filtered CSV — only the events matching your filters.
Filtered XLSX — a genuine Excel workbook with the filtered events.
Filtered TXT — a plain text file with the filtered events.

Exports respect all active filters, so you can extract exactly the subset you need.

No upload required

Log files can contain sensitive information — internal hostnames, user identifiers, error details. Filelume processes logs entirely in your browser. The content never leaves your device.

Start reading logs

Open the Log Viewer and load any .log, .txt, or .jsonl file. The parser detects the format automatically, and you can start filtering immediately.