Access Log Analyzer
Analyze web server access logs online — find 4xx and 5xx errors fast, with nothing uploaded
Free Online Access Log Analyzer
An access log records one line for every request a web server handled: who asked, what they asked for, when, and what the server answered. That is exactly the data you need when something breaks, and exactly the data that is unreadable in raw form once there are more than a few hundred lines. Paste an Apache or Nginx access log here and each request becomes a structured entry with its timestamp, request line, and status code. Responses in the 5xx range are marked as errors and 4xx as warnings, so the handful of failing requests separate themselves from the thousands that succeeded. The format is detected automatically, and the parsing happens in your browser, so a log full of visitor IP addresses is never uploaded.
Key Features
- Auto-detects the log format — Apache Common, Apache Combined, or Nginx combined
- Turns every request into a structured entry with timestamp, request line, and status
- Flags 5xx responses as errors and 4xx as warnings so failures are immediately visible
- One-click severity filter, plus keyword search across paths, referrers, and user agents
- Export the filtered entries as JSON, CSV, or plain text
- Entirely client-side — visitor IPs and request URLs never leave your browser
- Free with no sign-up and no upload quota
Common Use Cases
- Working out which endpoint returned 502s during an outage, and for how long
- Building a redirect map by listing every URL that produced a 404 after a migration
- Separating genuine visitors from bot traffic by filtering on the user agent
- Confirming a fix actually landed by checking that the errors stop at the deploy time
- Finding the referrer that is sending traffic to a page that no longer exists
- Reading a log from a client or production system without sending it to a third party
Frequently Asked Questions
How do I analyze a web server access log?
Paste the log into the box above and click Parse Logs. The format is detected automatically, and each request is broken out into a timestamp, request line, and status code. You can then filter to just the failures or search for a specific path. Click Load sample to see how it works before pasting your own.
How do I find errors in an access log?
After parsing, the severity badges show how many entries fell into each level. Click the ERROR badge to see only requests that returned a 5xx status, or WARN for 4xx. That reduces a log of thousands of lines to the small set that actually failed, which is usually where you want to start.
What formats does the access log analyzer support?
It reads the standard web server formats: the Apache Common Log Format, the Apache Combined Log Format, and the Nginx combined format. These are the defaults on virtually every Apache and Nginx install, so in most cases you can paste your log unchanged.
Can I export the parsed access log?
Yes. Export to JSON, CSV, or plain text. The export respects whatever filter is active, so you can isolate the 5xx requests and open just those in a spreadsheet or feed them into a script.
Is it safe to paste a production access log here?
Yes. The parsing is done in JavaScript in your own browser and no request is made to any server with your log contents. That matters because access logs routinely contain visitor IP addresses, session tokens in query strings, and internal URL structure.
Related Tools
- Nginx Log AnalyzerLocked to the Nginx combined format, with a sample to try.
- Apache Log AnalyzerLocked to the Apache Common and Combined Log Formats.
- Log File AnalyzerThe general analyzer — JSON, syslog, and plain text as well.
- HTTP Header CheckerInspect response headers for security, CORS, and caching.