ATW File

What are ATW files and how to open them

Are you having problems opening an ATW file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your ATW files.

What is an ATW file?

An .ATW file is an Anytime Organizer For Windows Data file.

AnyTime Organizer for Windows data files store personal organization information used by the Personal Information Manager software AnyTime Organizer, originally by Individual Software. They are created when the user saves their schedules, contacts, to-do lists, notes, passwords, expenses, and related personal data in AnyTime Organizer. The format is designed to encapsulate all these different types of data in a single file so the software can load and display a person's full set of organizer information. These files are typically written by AnyTime Organizer running on Windows 3.x and later versions, and are the native data store for that application.

Files in this format are read by AnyTime Organizer, which opens and parses the saved file to load all user data back into memory: calendars with appointments and events; contact lists with all the fields carried over (names, addresses, phone numbers etc.); to-do items including status and priorities; notes and password or expense records where supported. When the software is updated, older files typically must be converted to newer internal schema before they can be used.

Technical identification: the file begins with the ASCII signature "AnyTimeDataFileVersion2." at offset zero (hex bytes 41 6E 79 54 69 6D 65 44 61 74 61 46 69 6C 65 56 65 72 73 69 6F 6E20322E) which indicates version 2 of the Anytime Organizer / Windows file format.

How to open ATW files

Important: Different programs may use files with the ATW file extension for different purposes, so unless you are sure which format your ATW file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested three different ATW openers which you will find listed below.

Last updated: August 22, 2026

Various apps that use files with this extension

These apps are known to open certain types of ATW files. Remember, different programs may use ATW files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about ATW file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.