Open Outlook .pst and .ost files right in your browser - read emails, contacts and calendars, save attachments and export to .eml or .mbox, all without Outlook. Got a single message instead? Use the EML & MSG Viewer, or the MBOX Viewer for Thunderbird and Gmail mailboxes. A winmail.dat attachment opens in the DAT Viewer, and .ics invites in the ICS Viewer.
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Open your PST file. Drop the .pst or .ost file anywhere on this page, click to browse, or try the sample mailbox. Only the folder index is read at first, so even multi-GB archives open in seconds.
Pick a folder. The folder tree shows Inbox, Sent Items, Calendar, Contacts and every custom folder with item counts. Click a folder to list its emails, newest first.
Read and search. Click a message to read it with its formatting, recipients and attachments. Search the folder by sender or subject, or search the message text too.
Save what you need. Download attachments, save a message as .eml, or export the whole folder as an .mbox file, a ZIP of .eml files or a CSV list.
Keyboard shortcuts
Open a fileCtrl + O
Search this folder/
Next / previous message↓ / ↑
First / last messageHome / End
Folders← / → to fold
Leave full screenEsc
PST viewer features
Huge archives, low memory
The file is read in slices: first the folder index, then each message as you open it, so a multi-GB PST opens in seconds.
Every Outlook version
ANSI PST from Outlook 97-2002, Unicode PST from Outlook 2003 to Microsoft 365, and OST files including the Outlook 2013+ format.
Emails as they were sent
HTML, rich text (RTF) and plain text bodies, inline images, recipients, dates and internet headers with SPF, DKIM and DMARC results.
Safe to read
Each email is shown in a locked sandbox: scripts never run and remote images stay blocked until you allow them.
Attachments and attached emails
Preview images, PDFs and text, download one file or a ZIP of all of them, and open emails that were attached to other emails.
Contacts, calendar and tasks
Contact cards, appointments with times and attendees, tasks with due dates, notes and contact groups are shown as tidy cards.
Fast folder search
Filter by sender, subject or recipient as you type, then search inside the message text with one click.
Export without Outlook
Save messages as .eml, folders as .mbox or a ZIP of .eml files, and message lists as CSV - including an index of the whole archive.
What is a PST file?
A PST file (Personal Storage Table) is Outlook's archive format.
One .pst holds a whole mailbox: folders, emails, attachments, contacts, calendar items, tasks and notes.
You get one when you export a mailbox from Outlook, when AutoArchive moves old mail out, or when someone hands over a backup.
Normally you need Outlook for Windows to open one, which is why a PST viewer that runs in any browser is so handy for old backups.
PST and OST: what is the difference?
An OST file (Offline Storage Table) is the copy of an Exchange, Microsoft 365 or Outlook.com mailbox that Outlook keeps on your computer. It uses the same inner structure as a PST, so this viewer opens both.
The difference is ownership: a PST is a standalone archive, while an OST is a cache that Outlook rebuilds from the server and links to one account.
ANSI and Unicode PST files
Outlook 97 to 2002 wrote ANSI PST files, limited to 2 GB and to one language code page. Outlook 2003 and later write Unicode PST files, which handle every alphabet and grow to 50 GB by default in current Outlook versions.
The viewer detects the format by itself and shows it in the file header after opening.
How to open a PST file on any device
Every option below runs this viewer in the browser, so the steps are almost the same everywhere.
Windows
With classic Outlook installed, use File > Open & Export > Open Outlook Data File. Without Outlook, drop the .pst onto this page - if Outlook is running and uses the file, close it first, because Outlook locks open data files.
Mac
Apple Mail cannot read PST files. Outlook for Mac can import them, but that copies everything into your mailbox.
To just look inside, open this page in Safari, Chrome or Firefox and drop the file on it.
iPhone and iPad
Save the .pst to the Files app (from iCloud Drive, OneDrive, Google Drive or an email), open this page in Safari and tap browse. Large archives are fine, because only the folders and messages you open are read.
Android
Download the file, open this page in Chrome and pick the .pst from Downloads or your cloud drive. Messages open in a full-screen reading view with a back button to the list.
Chromebook and Linux
Outlook does not run on either, but any modern browser does - drop the file here, or use the other file viewers for the attachments you save.
How to convert a PST file
The viewer exports the most useful open formats straight from the PST, with no Outlook in between.
PST to EML - save one message from the reading pane, or a whole folder as a ZIP of .eml files. EML opens in Thunderbird, Apple Mail and the EML & MSG Viewer.
PST to MBOX - export a folder, with or without its subfolders, as one .mbox file for Thunderbird, Apple Mail or the MBOX Viewer.
PST to CSV - save the message list of a folder, or an index of every folder, and open it in Excel or the CSV Viewer.
Attachments - download them one by one or as a ZIP, then open spreadsheets in the Excel Viewer and PDFs in the PDF Viewer.
Contacts - open the Contacts folder to read every card; for a vCard file, export contacts from Outlook and check them in the VCF Viewer.
Every ZIP the viewer creates includes a short README, and nothing is ever sent to a server.
Why won't my PST file open?
Most problems come down to one of these.
Outlook is still using it - Outlook locks its open data files. Close Outlook (check the system tray too), then copy or open the file again.
The copy is incomplete - a file copied while Outlook was running, or a download that stopped early, ends too soon. The viewer warns about this and still shows what it can read.
The file is damaged - run Outlook's Inbox Repair Tool, SCANPST.EXE, on a copy (in Microsoft 365 it sits in C:\Program Files\Microsoft Office\root\Office16), then open the repaired file here.
It is a cloud placeholder - OneDrive and Dropbox can keep "online-only" stubs on disk. Make the file available offline before opening it.
It is not really a PST - Outlook for Mac archives (.olm), single messages (.msg) and Thunderbird mailboxes look similar at first glance. The viewer recognises them and points you to the right tool.
The ANSI 2 GB limit - very old PST files that grew past 2 GB are often corrupted at the end. Repair them with SCANPST first.
PST vs OST vs MSG vs EML vs MBOX
Email comes in a handful of file formats. This is how they compare.
Format
What it holds
Usually made by
Open it with
.pst
A whole mailbox: folders, mail, contacts, calendar, tasks
Outlook for Windows (export, AutoArchive)
This PST Viewer, Outlook for Windows
.ost
Offline copy of an Exchange, Microsoft 365 or Outlook.com mailbox
Need to look at an attachment you saved? Browse all file viewers for documents, images and archives.
Frequently Asked Questions
Drop the .pst file onto this page or click to browse. The folders, emails, attachments, contacts and calendar items open right in your browser.
No Outlook, Microsoft account or software install is needed, and it works on Windows, Mac, Linux, Chromebooks and phones.
No. The file is read by your own browser and never leaves your device - which matters for something as private as a mailbox.
Remote images inside emails are also blocked until you allow them, so senders cannot see that an old message was opened.
Yes. Open this page in Safari, Chrome or Firefox on your Mac and drop the PST file onto it.
Apple Mail cannot read PST files, and Outlook for Mac can only import them into a mailbox, so a browser viewer is the quickest way to look inside.
Yes. The viewer reads only the parts of the file you open - the folder index first, then each message on demand.
That way 10 GB and larger archives work without loading the whole file into memory, and folders with tens of thousands of messages still scroll smoothly.
Open the message and click an attachment to preview or download it. With more than two attachments, Download all saves them as one ZIP file.
Attached emails open inside the viewer too, with their own attachments.
Open the folder you want and use the export buttons under the viewer: .mbox writes one MBOX file, and .eml (ZIP) saves every message as an .eml file. Turn on Include subfolders to export a whole branch at once.
Single messages can be saved as .eml from the reading pane, and opened later in the EML & MSG Viewer.
Yes. OST files are Outlook's offline copies of Exchange, Microsoft 365 and Outlook.com mailboxes, and they share the PST structure - including the newer Outlook 2013+ OST format.
They open read-only; items Outlook never downloaded to that computer can be missing.
