View your Email Archives
Instantly and Securely

Mbox Viewer is a 100% private, client-side tool to read `.mbox` files from Google Takeout or other backups. Your data never, ever leaves your computer.

Install from Chrome Store for Free

Simple, Powerful, Visual.

See how easy it is to get started in just three steps.

1

Launch and Load

Open the extension and simply drag & drop your `.mbox` file or an entire folder. The application immediately starts processing your emails locally.

A screenshot of the Mbox Viewer application showing the drag and drop area for files.
2

Browse and Search

Your emails appear in a clean, intuitive interface. Use the powerful search bar to instantly find what you're looking for across thousands of messages.

A screenshot showing the main interface of Mbox Viewer with a list of emails.
3

Filter, View, and Export

Click on any email to view it in full. Use advanced filters for date ranges or attachments, and export important emails as `.eml` or `.pdf` files.

A screenshot of an opened email within the Mbox Viewer, showing the content and attachment options.

new_releasesNow on Version 1.5

We've rebuilt the engine from the ground up for massive archives.

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Rebuilt Processing Engine

Experience significantly faster and more stable performance, especially with multiple or complex Mbox files.

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New Dual-Mode for Huge Files

The app now intelligently switches to a robust database mode for archives over 1GB, preventing browser crashes. We've tested it on files up to 25GB.

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Performance & Expectations

The app processes roughly 1 million emails every 5 minutes. When loading very large files, your browser may warn that the page is unresponsive. This is expected. Please click "Wait". The app has not crashed.

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For the Nerds: Console Log

For the curious, open your browser's developer console (F12 or Ctrl+Shift+I) to see a detailed, real-time log of the import process, including speed and progress.

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Clear Error Codes

If something goes wrong, you'll see a specific code to help us diagnose issues much faster. Common codes include:

  • ERR-PARSE-001: File is likely corrupted.
  • ERR-DB-001: Browser database error.
  • ERR-PDF-001: Failed to generate PDF.

A Full-Featured Email Toolbox

Everything you need to manage your email archives, built with privacy as the priority.

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100% Private & Offline

All processing happens in your browser. Your files are never uploaded, ensuring complete data privacy.

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Blazing Fast Performance

Engineered to handle large Mbox archives (multi-gigabyte) without freezing your browser.

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Advanced Search & Filter

Instantly find emails by sender, subject, date, or content. Combine filters for precision searching.

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Light & Dark Modes

Switch themes for comfortable viewing day or night. Your preference is automatically saved.

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Multiple Export Options

Save individual emails as `.eml`, `.html`, or even print-ready `.pdf` files for archiving and sharing.

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Multi-File & Folder Support

Drag and drop multiple `.mbox` files or an entire folder from Google Takeout at once.

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Raw Source View

For technical users, inspect the complete, unaltered source code of any email, including all headers, with a single click.

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Email Security Insights

Instantly view the historical SPF, DKIM, and DMARC authentication results embedded in the email headers to verify sender authenticity.

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Secure Attachment Handling

Easily see all attachments associated with an email. Download them securely to your local machine for safe viewing.

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Chromebook Optimized

Designed to be lightweight and efficient, making it the perfect Mbox viewer for ChromeOS and other resource-constrained devices.

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Dual-Mode Engine (v1.5)

Intelligently switches between memory mode for speed and database mode for stability with huge archives (25GB+ tested).

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Preserves Data Integrity

The application opens your Mbox files in read-only mode. It will never modify or alter your original archive files, ensuring their integrity.

Your Questions, Answered

Getting Started

An Mbox file is a standard format for storing a collection of email messages. It's essentially a plain text file where emails are concatenated one after another. Services like Google Takeout and email clients like Thunderbird use this format to let you export and download your email data.

Go to Google Takeout, deselect all products, then select only "Mail". Follow the steps to create an export. Google will email you a link to a ZIP file. You must first unzip this file on your computer. Inside, you will find a `Mail` folder containing one or more `.mbox` files that you can drag into the viewer.

Security & Privacy

Yes, it's 100% secure. This is the most important feature. The tool is entirely client-side, meaning your files are never uploaded to our servers or any third party. All processing happens locally in your browser on your own computer.

Yes. After the initial installation and first load, the entire application is self-contained and works 100% offline. You do not need an internet connection to open and view your local Mbox files.

Never. The application opens your Mbox files in read-only mode. It will never modify or alter your original archive files in any way. This ensures the integrity of your backups is always preserved.

Core Features & Functionality

To provide the best performance and stability, the app automatically chooses how to handle your files:
  • Memory Mode (Files < 1 GB): Blazing fast and responsive, perfect for most day-to-day archives.
  • Database Mode (Files > 1 GB): For huge archives (we've tested up to 25 GB), this mode uses your browser's internal database (IndexedDB). It is much more stable and prevents crashes, but requires a one-time "Preparing database" step that can be slow to start.

The search bar performs a quick-filter on the 'From', 'To', and 'Subject' fields. For more advanced searching, you can combine this with filters, for example, to search for a specific word only in emails received within a certain date range that also have attachments.

You can see a list of all attachments for each email. For security reasons, the viewer does not generate previews directly in the app. Clicking an attachment will download it securely to your computer, where you can open it with your system's default application. This prevents any potentially malicious code from running in your browser.

These are email authentication standards that verify a sender's identity to prevent spam and phishing. Our viewer shows you the historic pass/fail status recorded in the email's headers, giving you insight into its authenticity at the time it was received.

Open the email you wish to save. Click the three-dot menu icon in the top-right of the email view panel. You can choose to export as `.eml` (a standard single-email file), `.html`, or `.pdf`. To print, we recommend exporting as a PDF first and then printing the resulting file.

Performance & Technical Questions

No, it is not broken. This is expected behavior with very large files. Processing gigabytes of text is extremely demanding for a web browser. When you see this warning, please click the "Wait" button. The app is working hard in the background and has not crashed. Processing speed is roughly 1 million emails every 5 minutes, depending on your computer's speed.

A web browser has limited access to your computer's RAM. For example, on a system with 4GB of RAM, a browser can typically only use about 1-1.5GB before becoming unstable. This is why we built our Dual-Mode system:
  • Memory Mode (Files < 1GB): For smaller files, the app loads everything into your browser's memory. This is extremely fast.
  • Database Mode (Files > 1GB): To prevent crashes with huge files, the app switches to using your browser's internal database. This initial setup is slower, but it allows the app to handle massive archives (25GB+) without crashing. This is the trade-off for stability.

Once a file is processed, all its data is stored for your current session (either in memory or the database). You do not need to drag and drop the file again to refresh the view. Simply clicking a sort button (e.g., "Date") or applying/removing a filter will instantly reload the email list from the already-processed data, which is much faster than starting over.

Error codes help us diagnose issues much faster. If you contact support, please include the code. Common codes include:
  • ERR-PARSE-001: Failed while reading the Mbox file. This usually means the file is corrupted or not a standard Mbox format.
  • ERR-DB-001: The internal browser database had a problem. This can happen if your browser has very limited storage space or is in a private/incognito mode that restricts database access.
  • ERR-PDF-001: Failed to generate a PDF, likely due to a very complex or non-standard email format. Try exporting as HTML instead.
  • ERR-ATTACH-001: Could not decode an attachment. The attachment data within the Mbox file may be corrupted.

The viewer has a resilient parsing system designed to skip over corrupted sections and load as much valid email data as possible. However, we offer no guarantees. If a file is severely corrupted, it may fail to load entirely. The application is a viewer and cannot repair a corrupted Mbox file.

No, never. This is a view-only application. It opens your Mbox files in "read-only" mode. It does not have the capability to write, edit, or alter your original files in any way. The integrity of your archive is always preserved.

If you encounter an issue, please use the support form at the bottom of this page. For the best assistance, please provide as much detail as possible, including:
  • The size of the Mbox file you are trying to view.
  • The browser and operating system you are using.
  • The exact error code you saw, if any.
  • A description of what you were doing when the problem occurred.

The extension is officially supported on the latest versions of Google Chrome, Microsoft Edge, Brave, and other browsers based on the Chromium engine. It is not available for Firefox or Safari.

Yes, absolutely! The viewer was designed with lightweight systems like Chromebooks in mind. Since it runs entirely in the browser and doesn't require heavy software installation, it's a perfect solution for ChromeOS.

Use Cases & Project Information

This tool is for quick, secure viewing without altering your primary email setup. It's perfect for:
  • Quickly searching a backup without the hassle of a full import.
  • Viewing an archive on a computer where you can't or don't want to install a heavy email client.
  • Ensuring the privacy of a sensitive archive, as the data is never indexed or stored permanently by the app.
  • Technical analysis of email headers and raw source code.

While the viewer provides an accurate representation of the Mbox content and is useful for initial review, it is not a certified forensic tool. For official legal proceedings, you should always consult with a digital forensics professional. The "Raw" view can be useful for inspecting unaltered source data.

Yes, it is completely free to use. There is no catch. We built this tool because we needed it ourselves and believe in creating useful, private software for everyone. We are supported by our parent company, Cloud Captains.

Yes, we are committed to maintaining and improving the Mbox Viewer. We are exploring new features such as more advanced filtering options and further performance enhancements for extremely large files.

Need Assistance?

Follow the steps below to submit a support request or question.

1. What is your inquiry about?

2. Please describe your request

3. Your Contact Details

4. Summary

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Request Sent!

Thank you. We have received your request. A confirmation has been sent to your email address.

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