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HAR Analyzer Online — Free HAR File Viewer & Request Inspector | DevFlow

HAR Analyzer & Request Replay

Analyze HAR files, inspect slow/failed requests, generate replayable curl/fetch code.

Free online HAR (HTTP Archive) analyzer. Upload or paste HAR files to inspect slow and failed requests, view waterfall timing breakdowns (DNS, SSL, TTFB, download), and generate replayable curl or fetch code. Identify performance bottlenecks, cache misses, compression issues, and third-party request problems. All processing happens locally in your browser — no data is sent to any server.

Keywords: har analyzer, har analyzer online, har file viewer, http archive analyzer, network request analyzer, har waterfall chart, analyze har file, har viewer online, inspect http requests, network performance analysis, curl generator from har, har to curl, har to fetch, replay http requests, debug network requests, har file inspector, slow request analyzer, failed request analysis

Tags: network, performance, debugging, http, api

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HAR Analyzer & Request Replay is also known as: HAR Viewer, HAR File Viewer, HTTP Archive Analyzer, Network Request Analyzer, HAR Waterfall Viewer.

How to HAR Analyzer & Request Replay Online

  1. Paste a HAR file JSON or upload a .har file from browser DevTools. Click Analyze or press ⌘↵.

  2. View the request list sorted by time, status, or domain. Slow requests (red) and failed requests (orange) are highlighted at the top.

  3. Click any request to view headers, timing breakdown, and response preview. The waterfall chart shows DNS, SSL, TTFB, and download phases.

  4. Select a request and click 'Copy as cURL' or 'Copy as fetch' to generate replayable code for terminal or code editor.

  5. Use filters to narrow down by domain, status code, or HTTP method. Toggle 'Compare' to load a second HAR for side-by-side analysis.

HAR Analyzer & Request Replay Features

  • Full HAR file parser supporting HAR 1.2 spec — parses all entries, timing, headers, and body content entirely in the browser.

  • Waterfall visualization with color-coded timing phases: DNS (blue), SSL/Connect (purple), Waiting/TTFB (green), Download (orange).

  • Slow request detection with configurable threshold (default 1s). Highlights requests exceeding the threshold in red.

  • Failed request filter — shows all 4xx/5xx responses and network errors in one view.

  • Request detail panel with tabs for Request Headers, Response Headers, Request Body, Response Body, and Timing Breakdown.

  • Curl generator — auto-escapes headers, handles POST body, produces copy-paste ready commands.

  • Fetch code generator — generates async/await JavaScript code ready to run in Node.js or browsers.

  • Cache analysis — identifies304 responses and missing Cache-Control headers.

  • Third-party request detection — flags requests to domains other than the main origin for privacy auditing.

  • Domain grouping with request count, average time, and total size per domain.

  • Status distribution chart — shows count per HTTP status code (200, 301, 404, 500, etc.).

  • Method distribution — GET/POST/PUT/DELETE counts at a glance.

  • Content-Type breakdown — categorizes by MIME type for media, scripts, styles, fonts, etc.

  • Side-by-side HAR comparison — load two HAR files to identify new/removed requests and timing regressions.

  • 100% client-side — your HAR data never leaves the browser. No server uploads.

  • Keyboard shortcuts: ⌘↵ to analyze, ⌘⇧C to copy selected curl, ⌘⇧F to copy fetch, ⌘⇧K to clear.

  • AI-powered explanations: ask AI to explain slow requests, suggest optimizations, or decode response bodies.

  • JSON export — dump full analysis as formatted JSON with ⌘⇧C for CI/CD pipelines.

Frequently Asked Questions

How do I generate a HAR file from my browser?
Chrome/Edge: Open DevTools (F12), go to the Network tab, make sure the record button (circle) is red, right-click anywhere in the request list > 'Save all as HAR with content'. Firefox: Network tab > gear icon > 'Save all as HAR'.
What's included in the waterfall timing?
Each request shows 6 phases: Blocked (queueing), DNS lookup, SSL handshake/Connect, Sending request, Waiting for first byte (TTFB), Receiving content. Longer bars indicate bottlenecks at that phase.
Can I analyze multiple HAR files at once?
Yes. Load your first HAR file, then click the 'Compare' button to load a second file. The tool shows side-by-side views with new/removed requests and timing diffs.
Is my data sent to any server?
No. All parsing and analysis happens entirely in your browser using JavaScript. Your network data never leaves your device.
How do I replay a request from HAR?
Select any request in the list, then use the 'Copy as cURL' or 'Copy as fetch' button in the detail panel. Paste the generated code into your terminal or code editor.
What do the timing colors mean in the waterfall?
Blue = DNS lookup, Purple = SSL/TCP connect, Green = Waiting (TTFB), Orange = Content download. Larger bar segments indicate where time was spent.
How do I filter requests?
Use the filter dropdowns above the request list: filter by domain (e.g., 'api.'), status code (404, 500), or HTTP method (POST, GET). Multiple filters can be combined.
What's the difference between this and Chrome DevTools?
DevTools is great for live inspection but requires keeping the tab open. HAR analysis is better for sharing with teammates, comparing before/after builds, and deeper timing analysis across sessions.
Can I export the analysis results?
Yes. Press ⌘⇧C or click 'Copy JSON' to copy the full analysis as JSON. This includes all entries, timings, domain stats, and status distributions.
How do I identify cache misses?
The tool marks 304 responses as cache hits and flags requests missing Cache-Control headers as potential cache misses. Check the Cache Misses filter.
What does 'third-party' mean?
Requests to domains different from the main page origin (e.g., analytics, CDNs, ads). These are flagged to help identify privacy-leaking third-party scripts.
Does the tool support HTTP/2 and HTTP/3 timings?
Yes. The HAR spec includes timing for HTTP/2 and HTTP/3. The tool parses whatever timing data is available in the HAR log.

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