# MBOX Viewer

> A free browser-based MBOX file viewer. Opens .mbox files from Google Takeout, Thunderbird and Apple Mail directly in the browser, with search, date and sender filtering, attachment extraction, and export to CSV, Excel, PDF, EML and MBOX. The mailbox is parsed entirely client-side and is never uploaded to any server.

MBOX Viewer runs at https://readmbox.com/ and is built by One Scales Inc.

## What it does

- Opens .mbox files of any size — tens of gigabytes — by streaming the file in small chunks rather than loading it into memory.
- Reads Google Takeout Gmail exports, Thunderbird mail stores and Apple Mail mailboxes.
- Full-text search across messages, plus filtering by sender, recipient, subject and date range.
- Optionally groups replies into conversations, threading on the Message-ID, In-Reply-To and References headers, so a reply whose subject was changed still sits with the thread it belongs to.
- Views and downloads individual attachments, or bulk-extracts every attachment across thousands of messages into a single ZIP, optionally filtered to images, PDFs or documents.
- Exports to CSV (opens in Excel and Google Sheets), Excel, PDF archive with cover sheet and page numbers, EML, and MBOX.
- Exports an addresses-only CSV: one row per email address, with how many messages that address sent and how many were sent to it, for seeing who a mailbox actually corresponds with.
- Requires no install, no browser extension and no account. Works in desktop Chrome and Edge; mobile browsers cannot handle files of this size.

## Privacy

- The .mbox file is read by the browser from local disk using standard File APIs. No message content, address, subject, filename or attachment is transmitted to any server, and none of it is stored anywhere.
- There is no upload endpoint and no mailbox storage of any kind.
- The website does use Google Analytics to count page visits, loads a web font from Google Fonts, and embeds a YouTube video via the no-cookie player. These relate to the page itself, not to mail data. Analytics never has access to mailbox contents.
- Purchasing an unlock key involves Stripe checkout; the resulting key is validated against a licence endpoint. No mail data is involved in that exchange.

## Pricing

- Free: read, search and filter any mailbox up to 50 GB, and export a single message. Above 50 GB the first 200 messages are free to browse.
- One-time $29 unlock: no file size limit, bulk export in every format, and bulk attachment extraction. No subscription and no recurring charge.

## File format background

MBOX is a plain-text format storing many email messages consecutively in one file. It is the format Google Takeout produces when exporting Gmail. Because it is a single large file rather than separate messages, ordinary desktop software often fails to open it.

## Links

- Homepage and app: https://readmbox.com/
- Features: https://readmbox.com/#what
- Privacy explanation: https://readmbox.com/#privacy
- FAQ: https://readmbox.com/#faq
- Support form: https://forms.gle/b8Rk2JJGoZmWjzUe9

## Publisher

One Scales Inc. — https://onescales.com/