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HAR File Analyzer

Analyze a HAR file with a request waterfall, blocking time, third-party breakdown by host, slow requests, headers, total transfer size and wall time.

HAR File Analyzer

File processing happens entirely in your browser. The HAR contents never reach any server.
(sample)

4 requests, 1 errors, 1 slow

Requests
4
Wall time
1.97 s
Transfer
187.3 KB
Errors
1
Slow (≥500ms)
1

Waterfall

200
220 ms
200
90 ms
200
1.45 s
500
80 ms
blockedfirst-partythird-partyerror (4xx/5xx)

Third-party breakdown

HostReqsBytesTime
cdn.thirdparty.io1175.8 KB1.45 s

Request detail

Select a row to inspect headers and timing breakdown.

Updated . Provided as is. Check the output before you rely on it in production.

How to use HAR File Analyzer

  1. 1

    Load your HAR

    Use Choose HAR file to read a .har export from Chrome, Firefox, or Safari DevTools. The file is parsed with FileReader and stays inside this tab.

  2. 2

    Scan the summary cards

    Requests, wall time, total transfer, error count, and slow-request count surface above the waterfall so you spot the page's biggest issues without scrolling.

  3. 3

    Filter and drill in

    Type into the filter to narrow by URL, host, or status. Click any waterfall row to open headers, MIME type, transfer size, and a per-phase timing breakdown.

  4. 4

    Triage third parties

    The third-party panel ranks external hosts by transferred bytes and total time, to see which vendor scripts dominate the page budget.

Questions and answers

What is HAR File Analyzer?
A HAR (HTTP Archive) file is a JSON export of every request a browser made while loading a page, with timings, headers and sizes. This analyzer reads one locally and shows request count, wall time, transfer size, errors and slow requests, a waterfall with blocking time, third-party hosts and per-request detail.
How big a HAR can it handle?
Most browser HAR exports under fifty megabytes parse and render comfortably. Large captures may slow the waterfall layout because every entry is rendered as an interactive row.
What counts as a third-party request?
A request is third-party when its host does not end with the hostname of the first page recorded in log.pages. The third-party panel groups by host and ranks them by transferred bytes.
Does the file leave my device?
No. The HAR is read with FileReader, parsed in memory, and rendered locally. There is no upload endpoint and no background fetch of the file contents to any server.
For AI agents: how to call this tool

Machine-readable contract, endpoints and examples. Humans can ignore this section.

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/har-file-analyzer/

For automation planning, fetch the canonical contract at /api/tool/har-file-analyzer.json.