Drop in a HAR file exported from your browser's Network panel to inspect every request: a waterfall timeline, status codes, headers, request and response bodies, cookies, timing phases and totals. The file is read locally and never uploaded.
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Open a .har fileDrag and drop it here, or choose a file. Exported from Chrome, Edge, Firefox or Safari DevTools (Network tab → Save all as HAR).
Export a HAR file: open DevTools (F12), go to the Network tab, reload the page and choose Save all as HAR (Chrome/Edge: download icon or right-click; Firefox: gear menu).
Open it here: drag the .har file onto the drop zone or press Choose HAR file. A sample HAR is loaded so you can try the viewer first.
Scan the waterfall and totals to spot slow requests, long waits (TTFB), large downloads and failed calls.
Filter by type, status or URL to focus on API calls, errors or a specific domain, and sort by size or time.
Click a request to see its headers, payload, response body, timing breakdown and cookies, or copy it as cURL.
Reading the timing phases
Phase (HAR field)
What it measures
If it is long
Queued / blocked (blocked)
Time waiting before the request could start (queueing, connection limits, lower priority)
Too many requests to one host, render-blocking resources, browser throttling
DNS (dns)
Resolving the host name to an IP address
Many third-party domains; consider dns-prefetch or fewer domains
Connect (connect)
Opening the TCP connection (includes TLS in HAR)
Distant servers; use a CDN, HTTP/2 or connection reuse
TLS (ssl)
The HTTPS handshake
Old TLS settings or no session resumption; enable TLS 1.3
Send (send)
Uploading the request headers and body
Large uploads or slow upstream bandwidth
Waiting / TTFB (wait)
Time until the first byte of the response arrived
Slow server code, database queries or cold caches
Download (receive)
Receiving the response body
Large files; compress, resize images or lazy-load
How to export a HAR file in each browser
Chrome and Edge: press F12, open the Network tab, reload the page, then click the Export HAR download arrow in the toolbar (or right-click any request and pick Save all as HAR with content). Firefox: press F12, open Network, reload, then use the gear menu and choose Save All As HAR. Safari: enable the Develop menu in Settings, open Web Inspector, go to Network, reload and click Export.
A HAR file captures cookies, tokens and anything you typed into forms during the recording. Record only what you need, and clean the file before sharing it with support teams.
Frequently asked questions
What is a HAR file?
HAR (HTTP Archive) is a JSON format that browsers use to save everything recorded in the Network panel: each request's URL, method, headers, cookies, status, timings and, optionally, the response bodies. Support teams often ask for a HAR file to troubleshoot slow or failing websites.
Is it safe to open my HAR file here?
Yes. The file is read with JavaScript inside your browser and is never uploaded. That matters because HAR files can contain cookies, authorization tokens and form data. Before sharing a HAR file with anyone else, remove or rotate sensitive values.
How do I export a HAR file in Chrome?
Open DevTools with F12 or Ctrl+Shift+I (Cmd+Option+I on Mac), select the Network tab, tick Preserve log if you need several pages, reload the page and reproduce the problem, then click the download arrow (Export HAR) or right-click a request and choose Save all as HAR with content.
What do the waterfall colors mean?
Gray is time spent queued or blocked, teal is the DNS lookup, orange is the TCP connection, purple is the TLS handshake, blue is sending the request, green is waiting for the first byte from the server (TTFB) and light blue is downloading the response. Long green bars point to slow servers; long light-blue bars point to large files or slow connections.
Why is the response body empty?
Browsers do not always store bodies in HAR files: redirects, cached responses and very large or binary resources are often left out, and some export options save headers only. In Chrome use Save all as HAR with content to include them.
What is the difference between transferred and resource size?
Transferred size is what went over the network, including headers and compression (and nearly zero for cached responses). Resource size is the decoded size of the body, which is usually larger for compressed text like JavaScript, CSS and JSON.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.