The DB file extension is used by mobile devices like Android, iOS, and Windows Phone 7 to store contact and SMS information. However, it may not be limited to such data but can also include any type of device and application data.

The software ArcView, a part of Esri's ArcGIS Desktop a GIS (geographic information system), uses the DB file extension for files that contain attribute data.

Database files were first implemented and used by dBase, a database management system developed by Cecil Wayne Ratliff. Starting in mid-80's, other companies produced their own version of the program along with their own spin into the file format. Currently, DB files are compatible with other xBase database programs because of its popularity.

Files with DB file extension are used in Microsoft Windows for its thumbnail cache and database. These files are found in all versions of the Windows OS. Examples of these files are thumbs.db, ehthumbs.db, image.db, and video.db. A thumbnail database is used to store thumbnail images so you can view image in the directory faster.

Files with the DB file extension is used by the Chinese online chatting program QQ for storing the contact list or the log of online chat sessions for an account. Files are used for storing data application locally and then loading it to the program interface.

The DB file extension is associated with the game called S.T.A.L.K.E.R... The files store database used S.T.A.L.K.E.R. X-Ray gaming engine.

Skype uses files with the DB file extension for their chat history file. These include all the instant messages, chat and call details sent and accepted by the user.

The DIGIBooster Module uses a file with the DB file extension for storing audio data composed through the Amiga music software.

The DB file extension associated with the Corel Paradox Database contains databases created by Corel Paradox.

One of the default file types used by SmartWare uses the DB file extension. It contains some sort of a database file.

The DB file extension is associated with Synopsys Design Compiler and used for its default data file type.

This file extension is associated with Microsoft Works, a discontinued office suite produced by Microsoft.

The Psion Series 3 uses the DB file extension for its default database file format.

The DB file extension is used for the configuration file from dBase, a database management system developed by dBase, LLC. These do not seem to be actual databases but just configuration files for the database.

The DB file extension is associated with Netscape Navigator. It is used to store client certificates and data related to that.

GroupWise, a collaborative software product by Novell, uses the DB file extension for files that contain address book database.

The DB file extension is used for one of the default files from the web browser Safari. It stores database with cache used by the browser.

The WhatsApp Messenger uses files with the DB file extension with its message database. This type of file stores database with the incoming and outgoing messages. The database file is called messagestore.db on BlackBerryand messages.db on Windows Phone.

The password managing tool Enpass uses files with the DB file extension to store encrypted database with passwords, logins, and other information.