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HAR File Viewer

Analyze HAR network captures: total weight, slowest and heaviest requests, failures

What is the HAR File Viewer?

The har file viewer works like this: it loads HAR (HTTP Archive) captures from DevTools and reports total page weight, load time, per-request status/size/timing, failures, and the slowest/heaviest offenders. Everything happens on your device - the input never leaves your tab unless the tool clearly states it performs a server-side lookup.

How to use the HAR File Viewer

1. Record the network log: DevTools → Network tab → reload the page → right-click → "Save all as HAR".
2. Drop the .har file here.
3. Read the summary first (weight, time, errors), then the Slowest and Heaviest tabs for your fix list.

Features

• Instant client-side formatting and validation
• No telemetry on your data
• Copy-ready output with proper escaping

Common mistakes to avoid

• Using the wrong input dialect (JSON vs JSON5, cron 5 vs 6 fields)
• Copying output without checking escaping

Examples

Input	Result
A 6 MB HAR from a slow product page	Heaviest request: a 2.4 MB unoptimized hero image - the fix is obvious in seconds

Best used for

• Getting a reliable answer for har file viewer without installing an app
• One-off tasks done in under a minute from any device
• Checking results before committing them to something important
• Working on a phone where desktop software is unavailable

Privacy

HAR files contain cookies and auth tokens from the recording session - this viewer parses them entirely in your browser, but be careful who you share the raw file with.

Frequently asked questions

Does the file leave my browser?

No - the HAR is parsed locally, which matters because HARs contain cookies, tokens and full request/response bodies.

Why is total size bigger than the page felt?

HARs include every request: images, fonts, analytics beacons, and failed retries that never render.

What is a HAR file and where do I get one?

An HTTP Archive capture of everything a page loaded - record one from your browser DevTools Network panel (Save as HAR) and drop it here to analyse.

Which metrics does the report lead with?

Total page weight, full load time, request counts by type, any failed responses, and the slowest individual requests ranked - the four numbers that explain most slow pages.

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• JSON Formatter - Format, validate, and beautify JSON code online

More like this

Zoven offers 200+ free browser tools. Browse by category - Calculators, Converters, Generators, Developer Tools and Media Tools - or read workflow guides on the Zoven blog.