Log Viewer for Large Files

v1.4.0Live

Inspect large log files with clean formatting, quick filters, and browser-only privacy.

⌘K

#	Timestamp	Severity	Message
243	10:00:01.452	INFO	Connection established on port 8080 from IP 192.168.1.42
244	10:00:02.105	DEBUG	Payload size: 1024 bytes. Parsing JSON body...
245	10:00:02.880	WARN	Latency spike detected in region us-east-1. Response time: 450ms
246	10:00:05.001	INFO	User authentication successful. Session ID: sess_892301
247	10:00:05.120	ERROR	Failed to write to database: connection timeout. at Database.connect (db.js:42)
248	10:00:06.332	INFO	Retrying connection (attempt 1/3)
249	10:00:06.400	WARN	Cache miss for key user_profile_882. Fetching from origin.
250	10:00:07.150	DEBUG	Health check: status 200 OK
251	10:00:08.012	INFO	Scheduled task 'CleanupTempFiles' started.

What this tool does

The Log Viewer loads text-based log files in your browser and presents them in a readable format. Paste logs or drop a file and the viewer keeps timestamps and levels aligned so you can scan quickly.

It is built for large files where standard editors struggle. Long lines remain readable, and consistent spacing makes error patterns and repeated events easy to spot.

All processing happens locally in the browser. There is no upload or login, so production logs and sensitive data stay private.

Why it is useful

Logs are noisy by nature. When you are hunting for a single error or a burst of warnings, a clean viewer helps you find signal without jumping between tools.

Support and operations teams frequently receive log snippets through tickets or chat. This tool gives them a quick, safe way to inspect the data without storing it elsewhere.

Browser-only parsing keeps things fast and compliant. You can review logs on a locked-down machine without installing anything.

Common use cases

Error triage

Scan for ERROR or WARN lines and confirm the surrounding context.

Performance reviews

Look for slow requests or repeated timeouts in large server logs.

Support investigations

Inspect a customer-provided log file without uploading it to third-party services.

Release validation

Check log output after a deployment to confirm expected events and health checks.

Data extraction

Copy a filtered subset of lines for a bug report or incident summary.

Workflow notes

Start with a short time window and confirm the log format. Once the pattern is clear, widen the scope to see trends. A consistent layout makes it easier to spot anomalies like bursts of errors or repeated retries.

Use consistent identifiers when searching, such as request_id or user_id. Logs often include multiple services, and a shared ID is the quickest way to connect events across systems.

If logs are structured, keep the raw line intact while you scan. Even when you filter, having the original line helps preserve context for incident reports and follow-up analysis.

Common pitfalls to avoid

Mixing log sources can create confusion when timestamps use different time zones. Confirm the time zone before drawing conclusions about ordering.

Very long lines can hide critical details past the wrap point. If something looks incomplete, check the full line and avoid truncation.

Avoid over-filtering. Narrow filters can hide the surrounding context that explains why an error occurred.

Practical guidance

Logs are most useful when you build a narrative. Start by identifying the event you care about, then expand outward in time to see what happened before and after. The viewer keeps timestamps aligned so you can follow that sequence without losing your place.

If you maintain multiple environments, verify which environment the log came from. A staging log can look similar to production, but the root cause and data may differ. Add environment markers or prefixes when possible so you can spot them quickly in the viewer.

When preparing an incident summary, extract a short, relevant subset of lines. Include the first error, any retries, and the final resolution. The viewer makes it easy to copy only the meaningful lines without sharing unrelated data.

Additional notes

When analyzing logs for performance issues, look for patterns like repeated timeouts or increasing response times. The viewer lets you scan for these patterns without running heavy analytics or exporting to another tool.

Consider redacting sensitive values before sharing log snippets. The viewer is private by default, but once you copy lines into a ticket they can spread quickly. Remove tokens, emails, or IDs you do not need.

Keep a simple naming convention for log files that includes date and service. When you open a file in the viewer, that context helps you avoid mixing incidents or misreading older data.

FAQ

Do logs get uploaded to a server?

No. Logs are parsed locally in your browser and never leave your device.

Can I filter by log level?

Yes. The viewer highlights common levels such as INFO, WARN, and ERROR to make them easier to spot.

What file sizes are supported?

Large files are supported, but performance depends on your device. If needed, start with a smaller slice.

Does it support JSON logs?

It works with raw text logs. For structured JSON lines, consider the JSON Viewer or JSON Formatter.

Can I export filtered results?

You can copy the filtered lines directly from the output area for quick sharing.

Is there a dark mode?

The UI focuses on clarity and contrast in light mode to avoid fatigue during long reviews.

DevTools