Open a PST file without Outlook
Drop an Outlook .pst or .ost archive and read, search, and export it on this page — on a Mac, a PC, or a Chromebook. No Outlook, no Exchange connection. The file is parsed on your own machine and never leaves your device.
How do I open a PST file without Outlook?
Use a viewer that reads the PST format itself instead of asking Outlook to do it. A PST is a single-file database described by Microsoft's public [MS-PST] specification — messages are stored as typed property sets inside B-trees, not as ready-made email text — so a direct reader walks that structure and rebuilds each message. Mailward does this in a Web Worker in your browser: the file is read locally with the File API in 64 KB pages, which is why multi-gigabyte archives open without being loaded into memory and why nothing is ever uploaded. It reads both PST variants (ANSI from Outlook 97–2002 and Unicode from Outlook 2003 onward) and OST offline caches, on macOS, Windows, Linux, or ChromeOS. Opening, browsing, and full-text search are free; only batch export is paid. One honest limit: a viewer cannot repair a damaged PST — if Windows' own scanpst cannot open the file, no viewer can.
Drop the .pst or .ost file — it is read locally, with nothing uploaded.
Browse the folder tree and open any message with its attachments.
Search across every folder by subject, sender, or body text.
Export one message free — or batch-export whole folders, the entire archive, and search results to MBOX / EML with Pro.
Open a PST file without Outlook
Use this viewer when you need to open a PST archive on a machine that never had Outlook — a Mac, a Chromebook, or a fresh laptop after someone leaves. Mailward reads the PST format directly in a Web Worker, streaming the file in pages so multi-gigabyte archives open without exhausting memory.
Reading, folder browsing, full-text search, and single-message export are always free; batch conversion is the paid step. No file ever touches a server.
On a Mac? macOS ships nothing that opens PST — readpst needs Homebrew and a terminal, and new Outlook for Mac won't export mail files. A browser tool needs no install at all.
What a PST file actually is
A PST (Personal Storage Table) is not a folder of emails — it is a single-file database. Microsoft publishes the layout as the [MS-PST] specification, which describes a node database of B-trees holding blocks, and a property layer that stores each message as a set of typed properties rather than as an RFC 5322 message.
That distinction is why converting a PST is harder than renaming it. There is no email text sitting inside the file waiting to be copied out: a reader has to walk the B-trees, resolve each message's property set, and then rebuild a standards-compliant message from those properties. Mailward does that reconstruction in a Web Worker on your machine.
PST comes in two incompatible variants. The ANSI variant, written by Outlook 97 through 2002, tops out at 2 GB and was notorious for corrupting archives that grew past it. The Unicode variant, introduced with Outlook 2003, is what almost every modern .pst uses. Mailward reads both, and tells you plainly when a file is beyond reading rather than failing silently.
Japanese archives deserve a specific mention. PST string properties carry a Windows or internet code page, and Japanese Outlook installations commonly mark bodies as ISO-2022-JP (code pages 50220/50221) or Shift_JIS (code page 932). The character-encoding library most JavaScript-based PST tools rely on has no ISO-2022-JP codec at all, so those bodies come out as mojibake — or abort the parse outright. Mailward decodes them with the browser's native TextDecoder instead, and catches a subtle mislabeling case: ISO-2022-JP is a 7-bit escape-sequence encoding, so if a property tagged ISO-2022-JP contains any byte of 0x80 or above, the data is really Shift_JIS and gets decoded as such.
- Format
- Single-file database ([MS-PST]), not a mail folder
- Variants
- ANSI (Outlook 97–2002, 2 GB ceiling) · Unicode (Outlook 2003+)
- Japanese encodings
- ISO-2022-JP and Shift_JIS/CP932 bodies decode natively — including CP932 data mislabeled as ISO-2022-JP
- Message storage
- Typed property sets — rebuilt into RFC 5322 on export
- Reads without Outlook
- Yes — the format is publicly specified
- Can a viewer repair a damaged PST?
- No. If scanpst cannot open it, neither can we
Comparing formats? PST, OST, OLM, MBOX & EML explained — what each one is internally, and what is lost converting between them.
Before you trust a mail file to a website
Q. Does my email really stay private?
Yes. The archive is read with the browser's File API and parsed in a Web Worker on your own machine. No part of it is sent to a server — you can disconnect from the network after the page loads and keep working.
Q. Do I need Outlook installed?
No. Mailward reads the PST format directly, so you can open an archive on a Mac, a Chromebook, or any machine that never ran Outlook.
Q. My PST is several gigabytes. Will it crash?
No. Mailward streams the file in pages instead of loading it whole, so multi-GB archives open without exhausting browser memory — the exact case where browser-based viewers usually fail.
Q. What if the file is corrupted?
A viewer cannot repair a damaged PST. If Windows' own scanpst cannot open it, neither can Mailward. We read healthy archives and tell you plainly when a file is beyond reading.
Simple, one-time pricing
Opening, reading, searching, and single-message export are free forever. Batch conversion is a one-time unlock — no subscription, no recurring fees.
Everything you need to open and read an archive.
- Open & read PST, OST, OLM, MBOX, EML, MSG — locally
- Full-text search across every folder
- Open a batch of .eml or .msg files as one merged list
- Export a single message, save any attachment
- Files never leave your device
Unlock batch conversion for good — a single payment, yours to keep.
- Batch-convert whole folders to MBOX or EML
- Export the whole archive in one click — folder tree preserved in the ZIP
- Export all search results as .eml files in one click
- Extract every attachment to a ZIP
- Open multiple archives side by side — one search covers them all
- Lifetime license — no renewals
Other formats & archives
Same local-first engine, every common mail format.