HAR Analyzer

HAR Analyzer: Open a HAR File and Find Slow Requests

Choose a HAR file and get a request waterfall with filters by type, domain and status, a list of errors, and the slowest and heaviest requests. The file is parsed on your computer and is never uploaded, which matters because a HAR usually holds cookies and auth tokens.

Runs in your browser. Your files never leave your device.

Drop a .har here or

A .har or .json export from browser DevTools, up to 100 MB. The file stays on your device.

Got the HAR as text in a ticket? Press Ctrl+V anywhere on this page.

Where the file comes from

  1. Open DevTools, Network tab, and reproduce the problem.
  2. Click the download arrow, or right-click a request and pick Save all as HAR with content.
  3. Drop the saved .har above. Nothing is uploaded.

Sample: checkout page, 48 requests. Drop your own HAR to replace it.

Requests
48
Failed
2
Transferred
1.9 MB
Total time
3.4 s

Failed 2

  • 500POSTapi.example.com/cart/apply-coupon
  • 0GETstatic.example.com/fonts/ui-sans.woff2blocked

Slowest top 3 of 10

  • 1,420 msapi.example.com/cart
  • 1,090 mscdn.example.com/app.js
  • 760 mscdn.example.com/hero.webp

Heaviest top 3 of 10

  • 812 KBcdn.example.com/app.js
  • 612 KBcdn.example.com/hero.webp
  • 48 KBcdn.example.com/app.css
Status Request Size Time 01 s2 s3 s
200 GET shop.example.com/checkout doc 14.2 KB 412 ms
200 GET cdn.example.com/app.css css 48 KB 188 ms
200 GET cdn.example.com/app.js js 812 KB 1,090 ms
0 GET static.example.com/fonts/ui-sans.woff2 font - 41 ms
200 GET cdn.example.com/hero.webp img 612 KB 760 ms
200 GET api.example.com/cart xhr 6.1 KB 1,420 ms
500 POST api.example.com/cart/apply-coupon xhr 0.4 KB 318 ms
blocked
2 ms
dns
-
connect
-
ssl
-
send
1 ms
wait
309 ms
receive
6 ms

Connection reused, so dns, connect and ssl do not apply. 309 ms of waiting before a 500 points at the server.

302 GET metrics.example.net/collect xhr 0.3 KB 96 ms

  • blocked
  • dns
  • connect
  • ssl
  • send
  • wait
  • receive

Clean copy replaces Authorization and Cookie headers, tokens in URLs and bodies, and JWTs with [redacted], and shows you the list before the download. The original on your disk is untouched.

How it works

  1. Export the HARIn DevTools open the Network tab, reproduce the problem, then use the download arrow or right-click a request and choose Save all as HAR with content. Firefox and Safari have the same export in their Network panels.
  2. Drop the file hereDrag the .har onto the page or pick it with the button. Big exports are parsed in a background thread, so the page stays responsive while a 50 MB file loads.
  3. Read the waterfallFilter by request type, domain or status code, sort by duration or size, and open any request to see headers, timings and the response body. Failed requests and anything slower than a second are listed on top.

What a HAR file analyzer shows that the Network tab hides

DevTools shows one session on one machine. A HAR file is that session saved to disk, so a colleague, a support engineer or a QA tester can open it later and see exactly what the browser saw: every request, its status, headers, cookies, timing phases (blocked, DNS, connect, SSL, send, wait, receive) and the response. This page adds what the raw JSON lacks: totals per domain, the share of time spent waiting on the server versus downloading, duplicate requests, redirect chains and the requests that failed outright. It reads HAR 1.1 and 1.2 exports from Chrome, Edge, Firefox, Safari and from proxies like Charles or Fiddler, and tells you which fields were missing instead of guessing.

Remove cookies and tokens before you share a HAR

A HAR export copies the Authorization and Cookie headers, Set-Cookie responses, session IDs in URLs and tokens inside JSON bodies. Anyone who gets the file can replay your login. The Clean copy button writes a new HAR with those values replaced by a placeholder: standard auth headers, cookies, query and #fragment parameters in every address in the file (Referer and Location included), and body fields with names like token, key, secret, password or session, and any JWT it finds. You see the list of what was replaced, and of what it could not check, before you download, and the original file on your disk is untouched. Check the result yourself before attaching it to a ticket; an automatic scrubber cannot know every custom header your app uses.

Questions

Is my HAR file uploaded anywhere?

No. The page has no server side. Parsing, filtering and the cleaned export run in your browser, and the file never leaves your device. The only requests the page makes after it loads are anonymous visit statistics (Google Analytics), and they never carry the file or anything from it. You can check this in the Network tab while you use it.

How large a file can it open?

Up to 100 MB in this version. Files above about 50 MB load in a lighter mode that keeps headers and timings but drops response bodies from memory. If your export is bigger, re-export from DevTools without content or clear the Network log before reproducing the problem.

Which browsers and tools produce a compatible HAR?

Any HAR 1.1 or 1.2 export: Chrome, Edge, Firefox, Safari, Charles, Fiddler, Proxyman, Playwright and Puppeteer. If a field is missing, for example timings in some proxy exports, the related column shows a dash instead of a wrong number.

More detail in the guide: How to Read a HAR File: Timings, Status Codes and What to Look For.