HAR File Analyzer

HAR (HTTP Archive) is a JSON-format file that records all HTTP requests and responses captured by a browser's DevTools network tab. It includes request/response headers, timings, body content, and status codes — making it ideal for performance debugging and API analysis.

Open DevTools (F12), go to the Network tab, reproduce the issue, then right-click any request and choose 'Save all as HAR with content'. In Firefox, click the gear icon in the Network tab and select 'Save All as HAR'.

The waterfall chart shows each request's total load time as a horizontal bar relative to the slowest request in the file. Longer bars indicate slower requests. This helps you identify bottlenecks in your page load sequence.

No — all analysis runs entirely in your browser using JavaScript. Your HAR file never leaves your machine, which is important since HAR files often contain sensitive data like authentication tokens and cookies.

Switch to the 'All' tab and use the Status and Type dropdown filters. You can filter to show only errors (4xx/5xx), only JSON responses, only images, and more.

Check the 'Slowest' tab for requests taking the most time, and 'Largest' for the biggest responses. Also look at the 'Errors' tab for any failed requests. High wait times often indicate slow backend processing, while large responses suggest data over-fetching.