HAR Analyzer
A tool that loads a HAR file exported from your browser's developer tools, computes an overall health score, and automatically diagnoses it across four angles: errors, speed bottlenecks, security/privacy, and resource breakdown. All analysis happens in your browser, and the file is never sent to an external server.
Drag and drop a HAR file
or click to choose a file (.har / .json)
Supported formats: .har, .json
How to use
- Drag and drop a HAR file, or load one via "Choose file" (you can export one from Chrome DevTools' Network tab by choosing "Save all as HAR").
- Once loaded, the overall health score appears along with automatic diagnostics across four tabs: "Error Detection", "Speed Bottlenecks", "Security / Privacy", and "Resource Breakdown".
- In the "Request list" below, filter by keyword, status code, or resource type. Click a row to open a drawer with the request/response headers, cookies, and query parameters.
- To analyze a different file, click "Load another file" to load a new one.
About this tool
The HAR Analyzer parses HTTP Archive (HAR) files entirely in your browser and automatically surfaces performance and security issues on a web page. It's useful for incident investigations, performance tuning, or reviewing a HAR file someone shared with you — cases where manually scanning raw JSON entry by entry would be tedious.
The overall health score (out of 100) is computed by deducting points for the number of 4xx/5xx errors, requests that take over 1 second to respond, missing key security headers (CSP, HSTS, X-Frame-Options, and more), the presence of non-HTTPS traffic, and uncompressed or oversized resources. Each tab shows the specific issues behind the score along with concrete improvement advice.
Resources are automatically categorized into eight types — document, JavaScript, CSS, image, font, API/XHR, media, and other — based on the URL extension, MIME type, and metadata such as the `_resourceType` field added by Chromium-based DevTools, so you can see the file size and request count ratio for each type.
Frequently asked questions
Where can I create or export a HAR file?
Open your browser's developer tools (Chrome, Edge, Firefox, etc.), go to the "Network" tab, reload the page, then right-click the request list and choose "Save all as HAR" (or a similarly named option) to save it as a HAR file.
How is the overall health score calculated?
Starting from a perfect score of 100, points are deducted based on the number of 5xx and 4xx errors, requests slower than 1 second, missing security headers, the presence of non-HTTPS traffic, and uncompressed or oversized resources. The breakdown behind the score is shown in each diagnostic tab.
Can it analyze large HAR files?
Yes, as long as your browser's memory allows it. For very large HAR files with several thousand entries or more, loading and rendering the list may take some time.
Is the HAR file I load sent to a server?
No. Loading, parsing, and diagnosing the file all happen entirely with JavaScript in your browser.