HAR File Analyzer
Load a Chrome or Firefox HAR capture in your browser and get a request waterfall, slowest requests, status-code breakdown, and total transfer size instantly.
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What is HAR File Analyzer?
A HAR File Analyzer loads an HTTP Archive (HAR) export from Chrome, Firefox, or Edge DevTools and turns it into a performance dashboard: a request waterfall, the slowest requests, a status-code breakdown, top hosts, total transfer size, and average duration. Instead of scrolling through hundreds of rows in DevTools, you load one file and immediately see which requests are slow, failing, or bloated. Everything is parsed locally in your browser, so sensitive captures stay on your machine.
Key Benefits
- Spot the slowest requests instantly instead of scrolling DevTools row by row
- Status-code breakdown surfaces 4xx and 5xx errors hiding in a long capture
- Waterfall view reveals serialized and long-running requests at a glance
- Total transfer size helps quantify how heavy a page really is
- CSV export and summary report make sharing findings with your team easy
Common Use Cases
- •Debugging a slow page load reported by users or monitoring
- •Reviewing what a third-party script or tag manager actually downloads
- •Auditing page weight before a performance budget review
- •Checking a production capture for failed or blocked requests
- •Sharing a concise network summary with backend or QA teammates
How to Analyze a HAR File
- Export the HAR file: Open Chrome or Firefox DevTools, switch to the Network tab, reproduce the slow page load, right-click the request list, and choose Save all as HAR with content.
- Load the capture: Upload the .har file or paste its JSON into the input box, then click Analyze.
- Read the overview: Check the request count, total transfer size, average duration, and page-load cards, then scan the status-code badges for errors.
- Find the bottlenecks: Review the slowest-requests table and the waterfall to spot long-running or serialized requests, then export the table as CSV if you need it elsewhere.
Key Features
- Visual request waterfall with bars colored by HTTP status class
- Top 5 slowest requests sorted by duration with method, status, and size
- Status-code breakdown and top-host request counts at a glance
- Overview cards for request count, total transfer, and average duration
- Export the full request table as CSV or copy a summary report
- Runs entirely offline - the HAR never leaves your browser
Frequently Asked Questions
What is a HAR file and where do I get one?
HAR (HTTP Archive) is a JSON log of every HTTP request a browser made, including URLs, status codes, timings, and sizes. Open Chrome, Firefox, or Edge DevTools, go to the Network tab, load a page, then right-click the request list and choose Save all as HAR with content.
Does my HAR file get uploaded to a server?
No. The analyzer parses the JSON entirely in your browser, so captures containing cookies, tokens, or proprietary API traffic never leave your device.
Why does the waterfall look a bit different from DevTools?
The waterfall is rebuilt from the startedDateTime and time fields of each entry, with bars positioned by start time relative to the first request. DevTools can draw slightly different shapes because it also has fine-grained phases like blocked, DNS, connect, and SSL.
What is the difference between page load time and average duration?
Page load time comes from the pageTimings onLoad value recorded by the browser and marks when the load event fired. Average duration is the mean of individual request times, which helps spot slow endpoints but says nothing about the overall timeline.