HAR Viewer — HTTP Archive Analyzer

Upload a HAR file exported from your browser DevTools to inspect requests, sizes, rich JSON viewer, and timings with a clear waterfall view.

Drag & drop HAR file or click to uploadExport a HAR from your browser DevTools (Network tab) and drop it here.

Features

Waterfall Timeline

Visualize when requests start and how long they take, grouped by MIME type color.

Request Table

Filterable list with method, path, status, type, time, and size.

Summary Stats

Totals for duration, requests, transfer size, and top domains.

Advanced Features

Rich JSON Viewer

Code and Tree modes for headers, payloads, and bodies with syntax highlighting.

Large‑File Friendly

Smart formatting path with Web Worker fallback for big JSON blocks.

Fullscreen Analysis

Expand filters and the waterfall timeline to focus on deep investigations.

Copy Anything

One‑click copy for headers, payloads, and response bodies.

Filters & Search

Type, Domain, and URL search filters to isolate the right requests fast.

Privacy‑First

Runs entirely in your browser — no uploads, no servers, no tracking.

Use Cases

Performance Debugging

Spot long requests, waterfall gaps, and heavy domains.

Third-party Analysis

Identify third-party hosts slowing down your page.

Regression Checks

Compare HARs across deploys to catch performance regressions.

Education

Teach network waterfalls and request lifecycles to teams.

What Is a HAR File?

A HAR (HTTP Archive) is a JSON log of all HTTP requests your page makes. This viewer transforms it into an easy‑to‑read report with a waterfall timeline and per‑request details — entirely in your browser for privacy.

Requests

  • Method, URL, HTTP version
  • Headers (e.g., Content-Type, Authorization)
  • Payload for POST/PUT (auto-formatted if JSON)

Responses

  • Status code and text
  • MIME type and size
  • Headers and body (with Base64 decoding & JSON pretty‑print)

Filtering & Focus

Type

Document, Script, Stylesheet, Image, Font, API/XHR, Other.

Domain

Limit to a hostname to isolate third‑party impact.

Search

Find requests by URL substring quickly.

Fullscreen

Expand filters + waterfall for deep analysis.

Performance Insights

Find slowest requests and blocking phases to speed up your pages.

Debugging Power

Inspect exact headers and payloads for failed or unexpected calls.

Third‑party Control

Measure the cost of external scripts, trackers and SDKs.

Privacy‑First

Runs 100% client‑side — your HAR never leaves your device.

Shareable Workflow

Attach HARs to bug reports to reproduce and fix faster.

Education

Teach network waterfalls and request lifecycles to teams.

Glossary

DNS

Domain lookup time before connecting to the server.

TTFB

Time to First Byte — server processing + network latency.

MIME Type

Content type of a response, e.g., text/html or application/json.

Caching

How resources are stored and re‑used to avoid repeat downloads.

Performance Best Practices

  • Minimize third‑party scripts and defer non‑critical ones.
  • Enable HTTP/2 or HTTP/3 for multiplexed requests.
  • Use strong caching headers for static assets.
  • Compress text responses (gzip/br) and optimize images.
  • Coalesce API calls and paginate server responses.
  • Monitor top domains and time‑to‑first‑byte in HARs.

Frequently Asked Questions

Is my HAR uploaded anywhere?
No. Analysis is 100% client‑side and stays on your device.
Can I copy headers and bodies?
Yes. Use the Copy buttons in Request, Response and Headers tabs.
How do I focus on API calls?
Select the API/XHR type filter and optionally a domain in the Domain filter.