Processed locally in your browser — not uploaded
AWS ALB Log Parser
Drop in an ALB access log file to get request counts, status-code and method distributions, target response-time percentiles (P50/P95/P99), and the slowest routes and requests. Parsing runs in a background thread so large files don't freeze the page. Nothing is uploaded — the file never leaves your browser.
Drag and drop an AWS ALB access log file (.log / .txt / .gz)
Parsed locally in a background Web Worker — zero data uploaded.
How to use
- Drag and drop an ALB access log file (or a text file with one log line per row) onto the drop zone, or click to browse.
- Parsing runs in a background thread (Web Worker) so the page stays responsive even on large files.
- Review summary metrics: status codes, methods, response-time percentiles, slowest routes and requests.
- Export the summary as CSV if you need to share or archive it.
Understanding the output
Target processing time is the time the backend target took to respond, in milliseconds — it excludes time spent in the load balancer itself. Entries where AWS reports -1 (the load balancer couldn't dispatch the request, e.g. a health-check or connection failure) are excluded from timing averages and percentiles, but still counted in the status-code distribution.
Common issues & tips
- •0 entries parsed: the file isn't in standard ALB access log format (space-delimited fields with quoted request/user-agent segments). CloudFront and Classic ELB logs use a different format.
- •Some lines skipped: usually truncated or manually edited lines with fewer than 14 fields.
Frequently asked questions
- Is my log file uploaded anywhere?
- No. The file is read and parsed entirely in your browser, in a Web Worker. It never leaves your machine.
- What does a target processing time of -1 mean?
- AWS uses -1 when the load balancer couldn't dispatch the request to a target — for example a health-check or connection failure. Those entries are excluded from the average and percentiles but still counted in the status-code breakdown.
- Does this work with Classic Load Balancer or CloudFront logs?
- No — this parser expects the standard Application Load Balancer (ALB) access log format specifically. Classic ELB and CloudFront use different log formats.