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Open MBOX File Online

Free MBOX viewer for email archives from Gmail (Google Takeout), Thunderbird, and Apple Mail. Open, search, read, edit, and export .mbox files — your email archive stays in your browser and is not uploaded.

Drop your .mbox file here

Supported: .mbox, .mbx, files without extension — Unix mbox, mboxo, mboxrd. Multiple files allowed. Processed locally, never uploaded.

How to Open an MBOX File

Four steps, entirely in your browser.

Export your mailbox as .mbox

Gmail: Google Takeout → Mail. Thunderbird: ImportExportTools NG. Apple Mail: Mailbox → Export Mailbox. Most mail servers can also produce mbox archives.

Drop the file on this page

Or click “Choose MBOX File”. Files without an extension and multiple archives at once work too. Parsing runs in a background worker with live progress.

Browse, search, and read

A three-pane layout like a desktop email client: folders and filters on the left, the message list in the middle, and a sandboxed reader on the right — with thread view, stars, labels, and notes.

Export what you need

Save single messages as .eml, print to PDF, or export selections and whole archives as .mbox, ZIP of .eml, CSV, JSON, or HTML.

Search Your Email Archive

Fast local search with Gmail-style operators.

Filter operators

from: to: cc: subject: label: after:2025-01-01 before: has:attachment is:read is:unread is:starred

Phrases & exclusions

Exact phrases in quotes — subject:"project update" — and negative terms with a minus: invoice -label:archive. Active filters appear as removable chips.

Everything searchable

Subjects, senders, recipients, full bodies, raw headers, attachment filenames, plus your own local labels and notes. Matches are highlighted in the list and message.

Convert & Export MBOX

From one message to the whole archive.

MBOX to EML

Save any message as a standard .eml file, or export a selection or the entire archive as a ZIP of .eml files — unedited messages stay byte-for-byte identical.

MBOX to CSV / JSON

Build a spreadsheet-ready CSV index (date, from, to, subject, Message-ID, attachments, labels) or a structured JSON export for further processing.

New .mbox & PDF

Re-export filtered selections as a clean new .mbox with correct From-line escaping, or print any message to PDF via the browser dialog.

Your email archive stays in your browser and is not uploaded.

Parsing, search, editing, and export all run locally on your device — there is no server that could receive your emails. HTML messages are sanitized and rendered in a sandboxed frame with scripts and forms blocked, and remote images and tracking pixels are blocked by default. No analytics, no tracking. Optional saving uses your browser’s own storage (IndexedDB) on this device only, and only after you explicitly choose “Save locally”.

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FAQ

How do I open an MBOX file?

Click “Choose MBOX File” at the top of this page or drag your .mbox file onto the dropzone. The archive is parsed locally in your browser and shown like a desktop email client — no signup, no install, no upload.

What is an MBOX file?

MBOX is a standard mailbox format that stores many email messages in a single plain-text file, separated by lines beginning with From . Gmail (via Google Takeout), Thunderbird, Apple Mail, and most mail servers export archives in this format. The common mboxo and mboxrd variants are supported.

Can I open a Google Takeout MBOX file?

Yes. Gmail exports from Google Takeout are standard MBOX files, and Gmail labels (X-Gmail-Labels) show up in the sidebar so you can filter by them.

Is this MBOX viewer private?

Yes. Your email archive stays in your browser and is not uploaded. There is no backend, no analytics, and no tracking. Remote images in HTML emails are blocked by default so senders cannot see that you opened a message.

Can I search inside an MBOX file?

Yes. Search across subject, sender, recipients, body, headers, and attachment names with operators like from:, subject:, after:, before:, has:attachment, is:unread, exact phrases in quotes, and -negated terms.

Can I view and download attachments?

Yes. Attachments are listed with name, type, and size. Images, PDFs, text, audio, and video can be previewed; anything can be downloaded individually or as a ZIP. Potentially unsafe file types (HTML, SVG, executables, macro documents) trigger a warning and are never opened automatically.

Can I edit emails in an MBOX file?

Yes — locally and safely. Edits create a working copy with undo, redo, and revert; the original file is never touched. Note that any modification invalidates DKIM, S/MIME, and PGP signatures, so edited exports are clearly marked.

Can I convert MBOX to EML, CSV, or PDF?

Yes. Individual messages export as .eml, text, HTML, JSON, or PDF (via print). Selections and full archives export as a new .mbox, a ZIP of .eml files, CSV metadata, JSON, or a combined HTML archive.

How large can my archive be?

Parsing runs in a Web Worker with chunked reading, and the message list is virtualized, so archives with tens of thousands of messages stay responsive. The practical limit is your device’s memory — multi-gigabyte archives may be slow on low-end hardware.

Does it work offline or from a local file?

Once loaded, the app works offline. Opening index.html directly from file:// is restricted by browsers (ES modules and workers are blocked); serve the folder over HTTP instead — see the README for a one-line command.