100% Private & Secure

Free OST Converter
Convert to Any Format

Convert Outlook OST to EML, MBOX, PST, CSV, HTML, TXT, or JSON. Private — no upload.

7 output formatsOffline OST supportFull email extractionInstant conversion

Drop OST file here

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Overview

What Is OST to JSON Conversion?

OST (Offline Storage Table) is Microsoft Outlook's format for storing a local copy of your mailbox when you use Exchange or certain account types. OST to JSON conversion takes that offline cache and exports each email as structured JSON — objects with fields like from, to, subject, date, and body, ready for apps, APIs, or scripts.

Our free OST to JSON converter processes entirely on your device. You drop a .ost file, and the tool validates the header, scans for email-like content, then generates a JSON array of message objects. All processing is private; nothing is uploaded.

Common use cases include feeding Outlook/Exchange cache into applications or APIs, importing into a database or search index, and automation or data analysis. Because the converter is private, you can use it on any operating system without Outlook.

OST files are typically found on Windows where Outlook has been used with Exchange; converting to JSON makes the content portable and machine-readable.

Features

Features

Why use our OST to JSON converter

Structured JSON output

Each extracted email is exported as a JSON object with from, to, subject, date, body, and other fields. Ideal for apps, APIs, or scripts.

OST binary parsing

Validates the OST header (ANSI or Unicode), scans for email-like content, and outputs valid JSON.

No upload

OST is read and converted entirely on your device. Your data never leaves your device.

API and app ready

JSON is easy to parse in Python, Node.js, or any language. Feed OST mail into databases, search indexes, or custom apps.

Preview before convert

See file info, extracted email count, and preview table before converting to JSON.

How it works

How to Convert OST to JSON

Four steps — no install, no Outlook

01
01

Open OST to JSON Converter

This page opens with JSON already selected as the output format.

02
02

Drop your .ost file

Drag and drop an Outlook .ost file. File info and extracted email count appear.

03
03

Review extracted emails

Browse the preview table. Each message will be exported as a JSON object in the output array.

04
04

Convert & download JSON

Click Convert & Download. You get a JSON file (array of email objects) for use in apps or scripts.

FAQ

Frequently Asked Questions

Common questions about OST to JSON conversion

Q1. What is OST to JSON conversion?
OST (Offline Storage Table) is Outlook's format for cached Exchange mailbox data. Converting OST to JSON extracts each email and outputs structured JSON objects (e.g. from, to, subject, date, body) so you can use the data in applications, APIs, or scripts.
Q2. Why convert OST to JSON?
JSON is the standard format for structured data. Use it to feed recovered Outlook/Exchange mail into databases, search engines, custom apps, or automation scripts. Every major language can parse JSON.
Q3. What fields are in the JSON?
Typically from, to, subject, date, and body (or content). The exact structure matches what the OST converter extracts. You can validate and parse the JSON in any programming language.
Q4. Do you upload my OST file?
No. Conversion runs entirely on your device. Your OST is read and parsed on your device. Nothing is sent to our servers.
Q5. Do I need Outlook installed?
No. The OST to JSON converter works on any modern platform — Windows, Mac, or Linux. No Microsoft Outlook or desktop software required.
Q6. Is the converter free?
Yes. The tool is free to use with no sign-up. File size is limited by your device's available memory (the tool scans the first 50 MB for content).
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