| .D1 | Progress Software Corporation | Fişiere de baze de date | Progress Database | ObjectStore | ESW Capital Group |
| .D2 | Progress Software Corporation | Fişiere de baze de date | Progress Database | ObjectStore | ESW Capital Group |
| .DAP | SpeedBit | Fişiere de baze de date | Download Accelerator Plus Partial Download | Download Accelerator Plus | SpeedBit |
| .DAT | Unknown Developer | Fişiere de baze de date | Game Data | Dragon UnPACKer | Open Source |
| .DATA | Appricon | Fişiere de baze de date | Analysis Studio Offline Data | Microsoft Excel | Microsoft Corporation |
| .DB | Dwayne Richard Hipp | Fişiere de baze de date | Mobile Device Database File | SQLite | Dwayne Richard Hipp |
| .DB-JOURNAL | Sublime HQ Pty Ltd | Fişiere de baze de date | SQLite Rollback Journal File | Microsoft Notepad | Microsoft Corporation |
| .DB2 | Samsung Electronics | Fişiere de baze de date | Samsung CCTV Video Information File | Samsung SmartViewer | Samsung Electronics |
| .DB3 | Dwayne Richard Hipp | Fişiere de baze de date | SQLite Database File | SQLite | Dwayne Richard Hipp |
| .DB4 | dBase, LLC | Fişiere de baze de date | dBASE IV Data | dBase | dBase, LLC |
| .DBA | PDC (Prolog Development Center) | Fişiere de baze de date | Turbo Prolog Database | Visual Prolog | PDC (Prolog Development Center) |
| .DBC | Microsoft Corporation | Fişiere de baze de date | FoxPro Database File | Microsoft Visual FoxPro | Microsoft Corporation |
| .DBF | dBase, LLC | Fişiere de baze de date | Database File | Microsoft Excel | Microsoft Corporation |
| .DBO | The Game Creators | Fişiere de baze de date | DarkBASIC Object | The Game Creators DarkBASIC Pro | The Game Creators |
| .DBR | Astonsoft | Fişiere de baze de date | DeepBurner Disc Project | DeepBurner | Astonsoft |
| .DBT | Abacus Data Systems | Fişiere de baze de date | AbacusLaw Data File | AbacusLaw | Abacus Data Systems |
| .DBV | multisoft Datentechnik GmbH | Fişiere de baze de date | Database Variable Field | dBase | dBase, LLC |
| .DBW | Ortus Solutions | Fişiere de baze de date | DataBoss Database | DataBoss | Ortus Solutions |
| .DBX | Microsoft Corporation | Fişiere de baze de date | Outlook Express E-mail Folder | Microsoft Outlook Express | Microsoft Corporation |
| .DCB | LexisNexis | Fişiere de baze de date | Concordance Database File | LexisNexis Concordance | LexisNexis |
| .DCT | Microsoft Corporation | Fişiere de baze de date | Dictionary File | QuarkXPress | Quark Software Inc. |
| .DCX | ZSoft Corporation | Fişiere de baze de date | Zsoft Multi-Page Paintbrush File | Adobe Photoshop | Adobe Systems Incorporated |
| .DDL | Oracle Corporation | Fişiere de baze de date | Data Definition Language File | MySQL | Oracle Corporation |
| .DF3 | Omnis Software | Fişiere de baze de date | Omnis Studio Database File Format | Omnis Studio | Omnis Software |
| .DF5 | Omnis Software | Fişiere de baze de date | Omnis7 And Omnis Studio Database File | Omnis Studio | Omnis Software |
| .DF6 | Omnis Software | Fişiere de baze de date | Omnis7 And Omnis Studio Database File | Omnis Studio | Omnis Software |
| .DIA | Spacetornado Software | Fişiere de baze de date | Do It Again Task File | Do It Again | Spacetornado Software |
| .DMO | Wouter van Oortmerssen | Fişiere de baze de date | Cube 2: Sauerbraten Demo File | Cube 2 Sauerbraten | Open Source |
| .DMU | Interscape | Fişiere de baze de date | Musicnizer Database File | Musicnizer | Interscape |
| .DNL | LexisNexis | Fişiere de baze de date | Concordance Database File | LexisNexis Concordance | LexisNexis |
| .DQL | Sapphire Group | Fişiere de baze de date | DataEase Database | DataEase | 4ThePeople Limited |
| .DQY | Microsoft Corporation | Fişiere de baze de date | Excel Query File | Microsoft Excel | Microsoft Corporation |
| .DRI | Microsoft Corporation | Fişiere de baze de date | Microsoft SQL Server Replication File | Microsoft SQL Server | Microsoft Corporation |
| .DSK | Power Software Ltd | Fişiere de baze de date | General Disk Image | PowerISO | Power Software Ltd |
| .DSN | Cadence Design Systems | Fişiere de baze de date | OrCAD Design File | OrCAD PCB Designer | Cadence Design Systems |
| .DXI | ZPAY Payroll Systems, Inc | Fişiere de baze de date | PayWindow Database File | PayWindow | ZPAY Payroll Systems, Inc |
| .DXL | IBM | Fişiere de baze de date | Domino XML Language File | Microsoft Notepad | Microsoft Corporation |
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