HAR Viewer
Open a .har network export and explore its requests, sizes, status codes, and a timing waterfall — entirely in your browser. Nothing is uploaded.
Prefer the terminal? See the CLI equivalent →About the HAR Viewer
- Waterfall timeline
- Per-request detail
- Timing breakdown
- Instant results
- 100% private — runs in your browser
- Free, no sign-up
A HAR (HTTP Archive) file is a JSON export of the network activity your browser recorded — every request, its headers, timing, size, and response. This tool opens one and lays it out like a DevTools Network panel: a searchable, filterable list of requests with status codes, resource types, sizes, and a timing waterfall you can read at a glance.
It is built for privacy. HAR files routinely contain cookies, authorization headers, and tokens, so sending one to a web service is genuinely risky. Here the file is parsed entirely in your browser — nothing is uploaded — which makes it safe to inspect a HAR captured from a production, authenticated session.
The waterfall breaks each request into its phases — blocked, DNS, connect, TLS, send, wait (time to first byte), and receive — so you can see where the time actually went and spot the slow requests, the 404s, and the oversized responses.
How to use it
- In your browser’s DevTools, open the Network tab, reproduce the activity, then right-click and choose “Save all as HAR”.
- Drop the .har file onto the box (or click to choose it).
- Read the summary, then filter by URL or resource type and scan the waterfall for slow or failed requests.
- Click any request to expand its headers, query string, and per-phase timings.
Waterfall phases
- Blocked
- Time queued waiting for a connection or a free socket.
- DNS
- Resolving the hostname to an IP address.
- Connect / TLS
- Establishing the TCP connection and the TLS handshake.
- Send
- Uploading the request to the server.
- Wait (TTFB)
- Waiting for the server — time to first byte; usually the largest slice.
- Receive
- Downloading the response body.
Frequently asked questions
Is my HAR file uploaded anywhere?+
No. It is read and parsed entirely in your browser with client-side JavaScript. Because HAR files often contain cookies, auth headers, and tokens from a real session, an offline tool is the safe way to inspect them.
How do I create a HAR file?+
Open your browser’s DevTools, go to the Network tab, reproduce the requests you care about, then right-click in the request list and choose “Save all as HAR” (Chrome/Edge) or use the download/export icon (Firefox).
What does “Wait (TTFB)” mean?+
Wait is the time between finishing the request and the first byte of the response arriving — “time to first byte”. A large Wait usually points at slow server-side processing rather than the network.
Why is a request’s size shown as “—”?+
The HAR didn’t record a transfer or content size for it (for example a cached response, or an exporter that omits sizes). The request is still listed with its status and timing.
Works well with
HAR Viewer chains with these tools — send your result straight on:
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