Drop in a .har file saved from the browser's Network panel. Every request is listed with its status, size and time on a waterfall, the slow and failed ones stand out, and any row opens to show headers and where the time went.
The HAR file is read in your browser and never uploaded. HAR files can hold cookies and tokens — remove them with the HAR Sanitizer before sharing one.
HAR — HTTP Archive — is a JSON format for recording everything a browser did while loading a page: every request and response, their headers, sizes and a timing breakdown for each one. Chrome, Edge, Firefox and Safari can all export one from the Network panel of their developer tools, which makes it the standard way to hand a slow or broken page load to someone else to analyse.
Each bar starts when the request started and is as long as it took. Requests that start late are waiting for something that came before them — usually a script or stylesheet that blocks the page, or a connection limit. Open a request to see where its time went:
Setting up a connection to a new host. Large values on third-party hosts (fonts, tags, CDNs) are a common hidden cost — every new domain pays them once.
Time to first byte: the server thinking. A long wait on the HTML document or an API call points at the back end, not the network.
Downloading the body. Large on big, uncompressed files — check that text is gzip or Brotli compressed and images are sized for the screen.
Queued in the browser before it could start — too many requests to one host, or lower priority than other resources.
A HAR file records the headers of every request, including Cookie, Set-Cookie and Authorization. Anyone who gets the file can often use those to act as you on the site until the session expires. Remove them with the HAR Sanitizer before you attach a HAR to a support ticket or a chat.
Choose the .har file above, or paste its contents. It is read in your browser, and every request appears in the table with its status, size, time and position on the waterfall. Click a row for its headers and timing breakdown.
No. The file is parsed by JavaScript in this page and never leaves your computer.
The Size column shows bytes transferred over the network, which is the compressed size plus headers. A 400 KB script sent with Brotli may transfer as 120 KB. Responses served from cache transfer almost nothing.
Status 0 means the browser got no HTTP answer: the request was blocked (CORS, an ad blocker, mixed content), cancelled by navigation, or the connection failed.
It can. Request bodies of login forms, cookies and Authorization headers are all recorded. Sanitize the file before sharing it.
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