Practical guide

How to Compare HAR Files for Network Debugging

Compare two HAR files to understand browser request changes. Learn how to review added and removed requests while keeping traces private.

Open HAR Comparison Tool

Quick answer

Use this guide when a flow works in one browser trace but fails in another. Comparing HAR files helps reveal missing requests, extra calls, or changed network behavior.

Who this is for

  • Frontend developers debugging network flows
  • QA teams comparing working and failing browser sessions
  • Support teams reviewing customer traces
  • Performance teams checking request changes

What to remove or avoid

  • Cookies and authorization headers before external sharing
  • Private request bodies and customer identifiers
  • Unneeded sensitive query values

What to keep visible

  • Request methods and URLs when safe
  • Status codes and request sequence
  • Added and removed request summary
  • Enough timing context to explain the issue

Useful controls in the tool

  • Upload the before HAR and after HAR.
  • Review added and removed requests.
  • Use fullscreen for long comparison reports.
  • Sanitize HAR files first before sharing them externally.

Step-by-step

  1. 1Export the working HAR and failing HAR.
  2. 2Load both into the comparison tool.
  3. 3Review added and removed requests.
  4. 4Check whether auth, redirects, or missing calls explain the issue.
  5. 5Share only sanitized findings.

Example

Before:
Before: GET /api/users
After: GET /api/users
After: POST /api/payment

After:
+ POST /api/payment

What to do after review

  • Use the HAR sanitizer before sending traces to third parties.
  • Confirm whether added requests are expected.
  • Check missing requests first when a page fails to load.
Tip: Compare HAR files to find request changes, then sanitize before sharing the trace.

Related tools

HAR Comparison Tool

Compare HAR exports and request changes.

Open tool
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