HAR File Analyzer — Free Online Tool Analyze HAR network captures locally. Find slow requests, failed responses, large transfers, and costly domains without uploading data.
Use this free online HAR File Analyzer directly in your browser. No signup required, no data leaves your device. Part of Utilier — a collection of 133+ developer utilities.
What is HAR File Analyzer? A HAR file is a JSON-formatted archive exported by browser DevTools that records network requests, responses, transfer sizes, timings, and headers for a page load. This analyzer reads a selected HAR file entirely in the browser and turns that dense capture into a quick performance summary.
Slow requests: Ranks the requests that consume the most elapsed time so an API, script, image, or third-party dependency is easy to identify.Domain grouping: Groups activity by host to reveal which first-party and third-party domains contribute most requests, transferred bytes, and failures.Local processing: The browser reads the file you choose; the HAR data is not uploaded to a server.Why use HAR analyzer? A network export may contain hundreds of requests and is difficult to inspect line by line. Sorting by duration, response status, and transfer size narrows a performance or reliability investigation to the requests most likely to matter.
When to use HAR analyzer Use it after exporting a HAR from browser DevTools, while diagnosing a slow page load, auditing third-party activity, or reviewing failed API calls. HAR files can contain cookies and authorization headers, so redact sensitive values before sharing one.
How to use HAR analyzer Export a HAR from the Network panel and choose it here.
Export the capture: In browser DevTools Network, save the captured requests as a HAR file.Select the HAR file: Choose the file from your device; it is parsed locally.Review the summary: Start with failures, largest transfers, slowest requests, and domains with the most total time.Key features Failure detection: Highlights 4xx, 5xx, and failed requests.Transfer analysis: Totals response sizes and reports large individual requests.No upload: Keeps a selected trace in the browser.Examples Slow API response GET /api/search - 2,400 msListed in Slowest requests with status, size, URL, and duration.Failed asset GET /assets/app.js - 404Counted as a failed request and grouped under its domain.Frequently asked questions Does the HAR file leave my device? No. The selected file is parsed locally in the browser.
What is a HAR file? It is a JSON archive of browser network activity, commonly exported from DevTools.
Why are HAR files sensitive? They can include URLs, request bodies, cookies, and authorization headers.
Privacy and availability Runs entirely in your browser — zero server processing No signup or account required Works offline once loaded Fast, lightweight, no external dependencies Available as a browser extension for Chrome and Firefox Tags HTTP Networking Related tools API Tester — Lightweight REST, GraphQL & WebSocket client with auth, body types, query params, and request history.cURL Converter — Convert a curl command to fetch, Axios, React, Python, Go, PHP, Java or Rust — and fetch back to curl.HTTP Header Analyzer — Parse HTTP headers locally and identify caching, CORS, cookie, and security-header concerns.HTTP Status Codes — Searchable reference of HTTP response status codes with their names and meanings.All developer tools JSON Beautifier & Validator — Format, minify and validate JSON. Reports the exact error location.HTML Beautifier & Minifier — Indent or minify HTML. Content of pre/script/style is preserved.CSS Beautifier & Minifier — Pretty-print or minify CSS. 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