Sign up free

OST to PDF Converter

Convert Outlook OST files to PDF with sender, recipients, date and message body. Private — nothing is uploaded.

Your files never leave your device

How to convert OST to PDF

  1. 1

    Choose your OST file

    Click the upload area or drag files onto it. Nothing is uploaded — files are opened locally.

  2. 2

    Adjust the settings

    Pick page size, then press the convert button.

  3. 3

    Download the result

    Save each file individually or everything at once as a ZIP.

Save emails from Outlook’s offline Exchange and Microsoft 365 mailboxes as PDFs for legal records, invoices, HR files or printing. Each message gets a header block with From, To, Cc, Date and Subject followed by the body text, and attachments are listed by name.

Read the full guide with screenshots

What is OST?

OST is Outlook’s offline copy of an Exchange or Microsoft 365 mailbox. It has the same structure as a PST but is normally tied to one account — converting it rescues mail from old or orphaned profiles.

What is PDF?

PDF (Portable Document Format) preserves a document’s layout on every device and operating system, which makes it the standard for sharing, printing and archiving.

Is it private?

Yes. Unlike upload-based converters, ZapMorph processes files inside your browser tab, so the file stays on your device. It is never transmitted, stored or logged — close the tab and it’s gone.

Frequently asked questions

Is the ost to pdf converter free?

Yes. Convert 1 file a day without an account, or 5 files a day with a free account. Pro removes all daily limits.

Are my files uploaded to a server?

No. The conversion runs entirely in your browser, so your files never leave your device. We only count how many files you convert — never their names or contents.

What is the maximum file size?

Up to 25 MB per file without an account, 50 MB with a free account, and 1 GB on Pro. Very large files also depend on your device’s memory.

Can I convert multiple OST files at once?

OST to PDF Converter works on one file at a time and can produce many output files, which you can download together as a ZIP.

Does it work on Mac, Windows, iPhone and Android?

Yes. It works in any modern browser — Chrome, Edge, Firefox and Safari — on desktop and mobile, with nothing to install.

Related converters

Merge PDF

Combine multiple PDF files into one document in the order you choose. Free, secure, no uploads.

Pro

Split PDF

Split a PDF into separate files — one per page or every few pages. Download them all as a ZIP.

Print Multiple Pages Per Sheet

Print 2, 4, 6, 8, 9, 10 or 16 PDF pages on one A4 sheet and drop pages you don’t need. Save paper on notes and slides. Free, private.

Compress PDF

Reduce PDF file size for email and upload limits. Choose lossless or strong compression. No upload.

Rotate PDF

Rotate every page of a PDF 90°, 180° or 270° and save it permanently. Free, instant, private.

Organize PDF Pages

Reorder, duplicate or drop PDF pages by typing the page order you want. Free and private.