ADT File

What are ADT files and how to open them

Are you having problems opening an ADT 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 ADT files.

What is an ADT file?

ADT files have multiple uses, and Act! Document Template is one of them. Read more about the other uses further down the page.

Act! Document Template

Act!, previously Sage Act, is a marketing and CRM software solution. It stores document templates for its built-in Word Processor with the .adt file extension.

How to open ADT files

We have identified one ADT opener that is compatible with this specific type of ADT file.

Programs that open Act! Document Template files

Last updated: August 17, 2026

All known file formats using extension .ADT

While Act! Document Template is a popular type of ADT-file, we know of 4 different uses of the .ADT file extension. Different software may use files with the same extension for different types of data.

Addict Thesaurus

These files are data files used by the Addictive Software "Addict" application. They store thesaurus content such as synonyms, antonyms, and related lexical information, for use by the Addict software to look up or suggest words while writing or editing text.

Origin and workflow Addictive Software's Addict program writes .ADT files when compiling or updating a thesaurus database. The software reads those files to provide thesaurus services: word look-ups, suggestions, and editing of thesaurus entries. Users may import or compile new thesaurus data via Addict, generating or modifying .ADT files.

Technical identifiers Files begin with the ASCII bytes "ADDICT" at offset 0, followed by a dot at offset 8, and the string "-ThesaurusCompiler" at offset 10. These header signatures uniquely identify Addict Thesaurus .ADT files among other formats that use the same .ADT extension.

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

Advantage Data Server table

These ADT files are database files that contain a single table. This database type is known as a Sybase Advantage Database. You can not open these ADT files directly; you have to connect to them using an ADS database engine. Using the Advantage Data Architect tool, you can export the table data and import it into databases like SQL servers.

Casio Pocket Viewer Add-in Data File

The Casio Pocket Viewer Add-in Data File is a data file used by Casio Pocket Viewer handhelds to back up or transfer user data and add-ins. These files are produced via the PV Application Manager utility on a computer and are used to save the device's user data (for example, application data, settings, or add-in data) in a single file that can later be restored to the Pocket Viewer.

When you connect your Pocket Viewer to the computer using PV Application Manager, selecting Backup on a folder such as the root of the device's user-data area creates a .ADT file holding the contents of that folder, enabling you to preserve or move your add-ins or data and later add them back by uploading that .ADT file.

Files of this type begin with an ASCII signature identifying them as Casio add-in-data files. The signature "CASIOADDINDATAFILE" appears at offset 0 (followed by a specific byte 0x1A and a zero byte), which distinguishes this format from other ADT-named formats.

Various apps that use files with this extension

These apps are known to open certain types of ADT files. Remember, different programs may use ADT 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 ADT file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.