100% Private & Secure

Free PST Analyzer
Analyze File Structure

Drop an Outlook .pst file to analyze header, format, encryption, and size. No upload — your data stays completely private.

Format detectionEncryption analysisSize breakdownRecommendations

Drop your .pst file here

or click to browse

Overview

What Is the PST Analyzer?

The PST Analyzer is a free online tool that inspects Outlook PST file structure. It validates the PST magic bytes ("!BDN"), reads the format version (ANSI vs Unicode from byte 10), encryption type (byte 513: 0 = none, 1 = compressible, 2 = high), and file size. It then shows a dashboard with file info, a size breakdown bar relative to the 2 GB ANSI and 50 GB Unicode limits, header analysis, and recommendations.

Full PST parsing (folders, messages, attachments) requires desktop software. This analyzer gives you a quick, private view of format, encryption, and size so you can plan migrations or verify backups without uploading your data.

All processing happens on your device. Your PST never leaves your computer — ideal for quick structure checks, migration prep, or compliance.

Features

Features of the PST Analyzer

Analyze Outlook PST structure with no install

Magic & format

Validates PST magic bytes (!BDN) and detects format version: ANSI (byte 10 = 14) or Unicode (23).

Encryption type

Reads byte 513: 0 = none, 1 = compressible, 2 = high encryption.

Size breakdown

Visual bar showing file size relative to ANSI 2 GB and Unicode 50 GB limits.

Recommendations

Contextual tips such as Unicode supports up to 50GB or ANSI 2GB limit warnings.

No upload

PST files are processed entirely on your device. Nothing is sent to any server.

Private & secure

Your PST file never leaves your device. Dashboard-style analysis with full privacy.

How it works

How to Analyze a PST File Online

Four simple steps — no install, no sign-up

01
01

Open the PST Analyzer

Go to the PST Analyzer page and you'll see the upload area.

02
02

Drop your .pst file

Drag and drop an Outlook .pst file, or click to browse and select one.

03
03

Review file info & header

See file name, size, format (ANSI/Unicode), encryption, and header analysis in a dashboard layout.

04
04

Check size & recommendations

View the size bar vs 2GB/50GB limits and read recommendations for your PST.

Use cases

Use Cases for the PST Analyzer

When and why to analyze PST files online

Format check

Verify a file is a valid PST and see ANSI vs Unicode without opening Outlook.

Migration prep

Analyze PST structure and size limits before migrating to another platform.

Encryption check

See whether the PST uses no encryption, compressible, or high encryption.

Size limits

Understand how your file size compares to the 2 GB ANSI and 50 GB Unicode limits.

No Outlook installed

Analyze PST files on a machine that doesn't have Microsoft Outlook.

Backup verification

Confirm backup or export files are valid PST with correct format and encryption.

Compare Plans

Free vs Paid — PST Analyzer

Get started free, upgrade when you need more power.

Feature
Free
Paid
Daily usage
5 uses/day
Unlimited
File size limit
10 MB
Up to 500 MB
All core features
No software installation
Works on any device
Files stay on your device
Batch processing
Priority support
Upgrade — starting at $6.99/mo
Upgrade to Full Version

Unlock the Full Power of PST Analyzer

Remove daily limits, process larger files up to 500 MB, enable batch processing, and get priority support.

Buy Full Version — $6.99/moor $300 enterprise

File Viewers includes:

  • 21 file viewers included
  • Unlimited daily uses
  • 100 MB file size limit
  • All file formats supported
  • Email analysis tools

Also available in the All Tools Bundle

FAQ

Frequently Asked Questions

Common questions about the PST Analyzer

Q1. What is the PST Analyzer?
The PST Analyzer reads an Outlook PST file on your device and parses its header to show magic validation, format version (ANSI vs Unicode), encryption type (byte 513: 0=none, 1=compressible, 2=high), file size, and a size bar relative to the 2 GB ANSI and 50 GB Unicode limits. It also shows recommendations based on the analysis.
Q2. Do you upload my PST file?
No. The PST Analyzer processes everything on your device. Only the header (first 576 bytes) is read for analysis. Nothing is sent to our servers.
Q3. What is ANSI vs Unicode PST?
ANSI PST (format byte 14) is older and has a 2 GB file size limit. Unicode PST (format byte 23) supports much larger files, up to 50 GB in practice. The analyzer detects this from byte 10 of the header.
Q4. What does encryption byte 513 mean?
Byte 513 in the PST indicates encryption: 0 = none, 1 = compressible encryption, 2 = high encryption. High encryption may require the original password for full access.
Q5. Can I see my emails and folders?
No. Full PST parsing (folders, messages, attachments) requires desktop software like Outlook or a dedicated PST tool. This analyzer only inspects the file header and structure.
Q6. Is the PST Analyzer free?
Yes. The tool is free to use with no sign-up and no limits.
Q7. What if the header is invalid?
The file may not be a standard PST, could be corrupted, or truncated. The analyzer will show recommendations and you can verify with Outlook or another tool.
Q8. Does it work on Mac?
Yes. Works on Windows, Mac, and Linux. No Outlook required.
Related

Related Tools

More file viewers from OnlinePCTools

PST ViewerOST ViewerMSG ViewerEML ViewerMBOX ViewerAll Viewers