Mailward
Opens and searches Outlook PST/OST files in the browser, no Outlook install needed.
Mailward parses PST and OST archives directly in a browser Web Worker, streaming the file in 64KB pages via the File API so multi-gigabyte archives open without loading into memory and nothing is ever uploaded. It reads both PST variants (ANSI from Outlook 97-2002 and Unicode from 2003+) plus OST caches, and decodes Japanese Shift_JIS/ISO-2022-JP encodings that a common JS library can't handle. Browsing, full-text search, and single-message export are free; batch export to MBOX/EML is the paid Pro feature. The maker states plainly that a damaged PST can't be repaired here — if Windows' own scanpst can't open it, neither can Mailward.
What holds up
- +Parses the file locally in your browser — nothing is ever uploaded to a server.
- +Handles multi-gigabyte archives by streaming 64KB pages, instead of loading the whole file into memory.
- +Decodes Japanese Shift_JIS/ISO-2022-JP encodings that a common JS library can't read at all.
Mind the limits
- −Batch export to MBOX/EML is paid — free use covers only single-message export.
- −Can't repair a damaged PST file — if Windows' own scanpst tool fails on it, Mailward can't open it either.
Picked here? Add the badge
Put it on your site. It links back to this page. Free for every listed product.
<a href="https://stillworks.dev/products/p/mailward/"><img src="https://stillworks.dev/badge/mailward.svg" alt="Picked by StillWorks" width="230" height="54"></a>