A HAR file is a JSON export of the browser Network panel. It contains request URLs, response statuses, timings, headers, content sizes, and related page metadata.

Are captured URLs or headers uploaded?

No. The HAR JSON is read by your browser and analyzed in the page. The tool does not call an API or send the file to a server.

What should I fix first?

Start with failed 4xx/5xx requests, the slowest requests, assets over 500 KB, weak caching on static assets, and missing security headers on the main HTML response.

Can I share the output with a teammate?

Yes, but review it first. HAR files and reports can expose private URLs, query strings, hostnames, cookies, or internal API routes.

Turn a slow-page complaint into a concrete issue

Export HAR from DevTools, paste the Markdown report into an issue, and include the top slow requests and oversized assets.

Review third-party cost before launch

Check how many requests go to external hosts and whether the main document is missing security headers.

HAR Performance Analyzer - local network export audit

Upload a Chrome DevTools HAR file and get a local performance, cache, host, asset, status, and security-header report.

Runs locally
Category Developer & DevOps
Best for Formatting, validating, shrinking, or inspecting code-adjacent text.

Load file

Runs locally in your browser. Files are not uploaded. Text limit: 8 MB.

Output format

Input

{
  "log": {
    "version": "1.2",
    "pages": [
      {
        "id": "page_1",
        "title": "https://example.com/",
        "startedDateTime": "2026-05-28T08:00:00.000Z"
      }
    ],
    "entries": [
      {
        "startedDateTime": "2026-05-28T08:00:00.120Z",
        "time": 420,
        "request": {
          "method": "GET",
          "url": "https://example.com/",
          "headers": []
        },
        "response": {
          "status": 200,
          "headers": [
            {
              "name": "content-type",
              "value": "text/html"
            }
          ],
          "content": {
            "size": 42000,
            "mimeType": "text/html"
          },
          "headersSize": 900,
          "bodySize": 14800
        }
      },
      {
        "startedDateTime": "2026-05-28T08:00:00.600Z",
        "time": 1280,
        "request": {
          "method": "GET",
          "url": "https://cdn.example.net/app.js",
          "headers": []
        },
        "response": {
          "status": 200,
          "headers": [
            {
              "name": "content-type",
              "value": "application/javascript"
            },
            {
              "name": "cache-control",
              "value": "max-age=3600"
            }
          ],
          "content": {
            "size": 860000,
            "mimeType": "application/javascript"
          },
          "headersSize": 700,
          "bodySize": 240000
        }
      },
      {
        "startedDateTime": "2026-05-28T08:00:01.100Z",
        "time": 260,
        "request": {
          "method": "GET",
          "url": "https://api.example.com/v1/profile",
          "headers": []
        },
        "response": {
          "status": 500,
          "headers": [
            {
              "name": "content-type",
              "value": "application/json"
            }
          ],
          "content": {
            "size": 1800,
            "mimeType": "application/json"
          },
          "headersSize": 600,
          "bodySize": 1800
        }
      }
    ]
  }
}

Output

# HAR Performance Report

- Requests: 3
- Transferred: 253 KB
- Response body: 251 KB
- Third-party requests: 2
- Failed requests: 1

## Status Buckets
| bucket | count |
| --- | --- |
| 2xx | 2 |
| 3xx | 0 |
| 4xx | 0 |
| 5xx | 1 |
| other | 0 |

## Slowest Requests
| method | status | time_ms | size | url |
| --- | --- | --- | --- | --- |
| GET | 200 | 1280 | 235 KB | https://cdn.example.net/app.js |
| GET | 200 | 420 | 15 KB | https://example.com/ |
| GET | 500 | 260 | 2.3 KB | https://api.example.com/v1/profile |

## Large Assets
No assets over 500 KB.

## MIME Types
| mime | count |
| --- | --- |
| text/html | 1 |
| application/javascript | 1 |
| application/json | 1 |

## Hosts
| host | requests |
| --- | --- |
| example.com | 1 |
| cdn.example.net | 1 |
| api.example.com | 1 |

Requests

Transferred

253 KB

Failed

Third-party

Warnings

Main HTML is missing security headers: content-security-policy, strict-transport-security, x-content-type-options, referrer-policy
1 cacheable-looking assets have weak Cache-Control.

What this tool does

HAR Performance Analyzer turns a browser network export into a readable engineering report without sending the capture anywhere. Load a `.har` file from Chrome, Edge, Firefox, or another browser, and the tool summarizes request count, transferred bytes, body bytes, failed requests, third-party hosts, MIME types, the slowest requests, large assets, weak cache headers, and missing security response headers on the main HTML document.

It is built for the moment after a page feels slow but before you open a heavy observability product. Product engineers can paste the Markdown into an issue, performance owners can export the request table as CSV, and founders can check a landing page capture before asking someone to optimize it. The JSON output keeps the raw metrics structured enough for follow-up automation.

Tool details

Input: Files + Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy + Download; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 36 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Developer & DevOps · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How HAR Performance Analyzer fits into your work

Use it in the small gaps between coding, reviewing, debugging, and shipping.

Developer jobs

Formatting, validating, shrinking, or inspecting code-adjacent text.
Preparing snippets for documentation, tickets, commits, or handoff.
Checking a small payload quickly without switching tools.

Developer checks

Run irreversible transforms like minify or obfuscate on a copy.
Keep secrets out of pasted snippets unless the tool explicitly stays local.
Use your normal tests or linter before shipping transformed code.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Turn a slow-page complaint into a concrete issue
Export HAR from DevTools, paste the Markdown report into an issue, and include the top slow requests and oversized assets.
Review third-party cost before launch
Check how many requests go to external hosts and whether the main document is missing security headers.

Common pitfalls

A HAR export can include sensitive URLs and headers, so do not publish the raw file.
Transfer size can be browser-dependent when cache is involved; compare captures under the same cache setting.

Privacy

HAR parsing runs locally. Review reports before sharing because URLs, query strings, and hostnames may still be sensitive.

FAQ

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Folks in your role tend to reach for these alongside this tool.

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HAR Performance Analyzer - local network export audit

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How HAR Performance Analyzer fits into your work

Developer jobs

Developer checks

Good next steps

Real-world use cases

Turn a slow-page complaint into a concrete issue

Review third-party cost before launch

Common pitfalls

Privacy

FAQ

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