What Is a HAR File?
A HAR (HTTP Archive) file is a JSON-formatted log that web browsers can export, capturing every network request made during a browsing session. It records request URLs, headers, response codes, timing data, cookies, and payload sizes. HAR files are essential for performance auditing, debugging slow API calls, investigating failed requests, and documenting network behavior for QA or bug reports.
Why This Tool Exists
HAR files frequently contain sensitive data — session cookies, authentication tokens, API keys embedded in headers, and private request payloads. Most online HAR analyzers require you to upload the file to a remote server, which is a significant security risk for professionals working with production traffic or confidential API data.
HAR Analyzer was built to eliminate that risk entirely. The entire analysis engine runs in your browser. Your HAR file is read locally using the browser's File API, parsed in memory, and never transmitted anywhere. You get full analysis capabilities without any privacy compromise.
What You Can Analyze
- Request timeline — Visualize every network request in chronological order with timing breakdowns.
- Slow request detection — Identify the slowest API calls and static asset loads dragging down page performance.
- Status code filtering — Filter requests by HTTP status code to quickly surface all 4xx and 5xx errors.
- Header inspection — Examine request and response headers for cache-control policies, content types, and CORS settings.
- Payload size analysis — Find oversized responses that are inflating your page weight and transfer times.
- Domain grouping — See which domains are generating the most requests and bandwidth usage.
How to Export a HAR File
In Chrome or Edge, open DevTools (F12), go to the Network tab, reproduce the issue or page load, then right-click any request and select "Save all as HAR with content." In Firefox, use the Network tab → gear icon → Save All As HAR. Then drag and drop the file into this tool for instant analysis.
Built for Privacy
This tool was built by a solo developer who believes that security tooling should not itself be a security risk. Your HAR file stays in your browser — always. No upload, no server, no retention.