How to Open and Extract a HAR File

What a HAR file is and why you need to open it

A HAR file (HTTP Archive) is a record of everything your browser sent and received while loading a web page — every image, script, stylesheet, and data request, along with timing information and response details. Your browser creates it automatically; you just need to save it. Opening a HAR file means reading that record, usually to see why a page loaded slowly, why something didn't work, or to share the data with a developer who can diagnose the problem.

HAR files are plain text files formatted as JSON, so you can open them in any text editor. However, a text editor shows you raw code that is hard to read. Most people use a dedicated HAR viewer — a tool that organizes the data into tables and charts — or import the file into your browser's developer tools, where you can see exactly what happened during page load.

The file itself is small, usually under a few megabytes, and contains no executable code, so it is safe to open and share. The main thing to know is that a HAR file records URLs you visited and data you sent, so be careful about sharing it with people you do not trust.

Key Takeaways

A HAR file is a text record of all network activity that happened while you loaded a web page, saved by your browser.
You can open a HAR file in any text editor, but a dedicated viewer or your browser's developer tools will show the data in an organized, readable format.
Chrome, Firefox, and Edge all have built-in tools to view HAR files without installing anything extra.
Before sharing a HAR file with anyone, review it for sensitive information like passwords, tokens, or personal URLs.

Open a HAR file in your browser's developer tools

The fastest way to view a HAR file is to use the tool that created it — your browser's developer tools. Chrome, Firefox, and Edge all have a Network tab that can import and display HAR data in a readable format.

In Chrome or Edge: Open developer tools by pressing F12 or Ctrl+Shift+I (Windows) or Cmd+Option+I (Mac). Click the Network tab. Right-click anywhere in the Network panel and select "Import HAR file". Choose your HAR file from your computer. The Network tab will now show all the requests, responses, and timing data in organized columns — you can click any request to see its full details.

In Firefox: Open developer tools with F12 or Ctrl+Shift+I (Windows) or Cmd+Option+I (Mac). Click the Network tab. Click the settings icon (three horizontal lines) in the top right of the Network panel, then select "Import HAR". Choose your file. Firefox will display the same organized view of all network activity.

Once the file is imported, you can sort by request type, size, or time, and click any entry to see headers, response body, cookies, and timing breakdowns. This is the best way to diagnose loading problems because you can see exactly which requests were slow or failed.

Open a HAR file in a text editor

If you just need to look at the raw data or do not have a browser handy, any text editor will open a HAR file. On Windows, right-click the HAR file, select "Open with", and choose Notepad or any text editor you have installed. On Mac, right-click (or Ctrl+click) the file, select "Open With", and choose TextEdit or another editor.

The file will display as JSON — structured text with curly braces, square brackets, and key-value pairs. It is readable but dense. You can search within the file using Ctrl+F (Windows) or Cmd+F (Mac) to find specific URLs, response codes, or timing data. If the file is very large, a text editor may slow down, so the browser method is usually faster.

Some text editors, like Visual Studio Code, have built-in JSON formatting that makes the file easier to scan. If you open the file and it looks like a jumbled block of text, your editor may not be formatting it. Try copying the contents into an online JSON formatter (search "JSON formatter" in your browser) to see the structure more clearly.

Use an online HAR viewer

If you do not want to use your browser's developer tools, several free online HAR viewers will display the file in a clean, organized format. Popular options include HAR Viewer (hosted by the W3C), Fiddler's online viewer, and Waterfall — each shows request timelines, response details, and performance metrics in a visual layout.

To use an online viewer: go to the viewer's website, click the upload or import button, and select your HAR file from your computer. The viewer will parse the file and display all network requests in a table or timeline. You can then click individual requests to see headers, cookies, response body, and timing information.

The advantage of an online viewer is that you do not need to open developer tools or install software. The disadvantage is that you are uploading your HAR file to a third-party server. Since HAR files can contain sensitive data (URLs, tokens, cookies), only use an online viewer you trust, or review the file in a text editor first to remove sensitive information.

Create a HAR file from your browser

Before you can open a HAR file, you need to create one. Your browser records network activity automatically — you just need to save it.

In Chrome or Edge: Open developer tools (F12 or Ctrl+Shift+I). Click the Network tab. Make sure the red record button in the top left is active (it should be by default). Load the page you want to record, or perform the action that is causing a problem. Once the page has finished loading, right-click anywhere in the Network panel and select "Save all as HAR with content". Choose where to save the file on your computer.

In Firefox: Open developer tools (F12 or Ctrl+Shift+I). Click the Network tab. Load the page or perform the action you want to record. Once finished, right-click in the Network panel and select "Save All As HAR". Choose your save location.

The file will be saved with a .har extension. It will contain all requests made during the time the Network tab was open, so close the tab or clear it before recording if you want to exclude earlier activity.

Review a HAR file for sensitive information before sharing

HAR files record everything your browser sent and received, which can include passwords, authentication tokens, API keys, personal URLs, and cookie data. Before you share a HAR file with a developer, support team, or anyone else, open it in a text editor and search for sensitive information you want to remove.

Look for entries containing "password", "token", "key", "authorization", "cookie", or any personal data. You can delete entire request objects (the sections enclosed in curly braces) or edit specific fields to remove sensitive values while keeping the structure intact. Save the edited file and share that version instead.

If you are not sure what is safe to share, ask the person requesting the file what they need to see. Often they only need to see timing data and request URLs, not response bodies or headers. Removing the response body is usually safe and removes most sensitive data.

Frequently Asked Questions

Can I open a HAR file on my phone?

Most phones do not have a built-in HAR viewer. You can email the file to yourself and open it on a computer, or use an online HAR viewer from your phone's browser. Some mobile browsers like Chrome have developer tools, but importing HAR files is not always supported on mobile versions.

What if my HAR file will not open in developer tools?

The file may be corrupted or not a valid HAR file. Try opening it in a text editor first to confirm it starts with a curly brace and contains JSON. If it looks like gibberish, the file may have been saved incorrectly. Try creating a new HAR file by recording network activity again. If the file is valid JSON but your browser will not import it, try a different browser or an online viewer.

How large can a HAR file be?

A typical HAR file is a few hundred kilobytes to a few megabytes, depending on how many requests were made and how much data was transferred. Very large files (over 50 MB) can slow down text editors and some viewers. If your file is huge, try opening it in your browser's developer tools rather than a text editor, or split the recording into smaller sessions.

Do I need to install software to open a HAR file?

No. Your browser's developer tools are built in, and any text editor will open the file. Online viewers require no installation either. The only reason to install software is if you want a dedicated HAR analysis tool with advanced features, but that is not necessary for basic viewing.

Can I edit a HAR file and save it?

Yes. Open it in a text editor, make changes to the JSON (being careful not to break the structure), and save it with the .har extension. You can then import the edited file into developer tools or a viewer. This is useful for removing sensitive data before sharing, but be careful — if you accidentally delete a curly brace or comma, the file will no longer be valid JSON.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.