What is the ADP file format?
Files with the .adp extension belong to the category of database project files used by Microsoft Access.
What do ADP files contain?
Contents of .adp files are information utilized by Microsoft Access to enable working with databases in a client-server mode. .adp files do not contain any database fields such as tables, columns, or indexes, but exclusively information necessary to access the content of the database from the level of dedicated software - specifically form definitions, report layouts, VBA code, and an OLE DB connection string to Microsoft SQL Server or MSDE.
What are ADP files used for?
Files with the .adp extension provide users access to information stored in databases on servers, utilizing SQL technology. Thanks to this, one can not only retrieve the content of database records but also modify their content, alter the structure of the entire database, and manage stored procedures and views directly from the Access interface.
The format was introduced in Access 2000 and last supported in Access 2010. Access 2013 and all later versions cannot open .adp files. Users needing to migrate should use Access 2010 to export the project to an .accdb file with linked SQL Server tables, or use the SQL Server Migration Assistant (SSMA).
Security & safety
RISK: LOWADP files can contain VBA macros (same risks as MDB/ACCDB macro files). Treat as you would any Office file with macros. Risk is low in practice since these are legacy enterprise files.
Format details
in a nutshell- ADP Audio (ADPCM) file - Some audio software uses .adp for Adaptive Differential Pulse-Code Modulation audio data (unrelated to Access).
- Automatic Data Processing file - ADP payroll/HR exports may use .adp extension in some legacy systems.
Programs that open ADP files
Windows2 apps
Microsoft Access 2010
Paid Open Access 2010, File > Open, select the .adp file. Access 2010 is the last version that supports ADP. Technical details
deep spec| Container | OLE2 Compound File Binary (CFBF) |
| Magic bytes (offset 0) | D0 CF 11 E0 A1 B1 1A E1 (OLE2 compound document signature) |
| Byte order | Little-endian |
| MIME type | application/msaccess |
| Typical file size | 50 KB - 5 MB (schema and UI only; all data resides on SQL Server) |
| Local data storage | Connection-only architecture; no tables or records - only form/report definitions, VBA code, and OLE DB connection string |
| Database connection method | OLE DB connection string to Microsoft SQL Server or MSDE, stored in the file |
| Supported Access versions | Access 2000 through Access 2010 (read/write) |
| Access 2013 and later | Cannot open ADP files; the Access Data Project feature was discontinued |
| Internal format version | Access 2002-2003 format (applied uniformly to all ADP files regardless of Access version) |
| VBA project | Full VBA project embedded: modules, class modules, form code-behind |
| SQL Server objects accessible | Tables, views, stored procedures, triggers, database diagrams |
| Migration target | ACCDB with linked SQL Server tables, via Access 2010 export or SQL Server Migration Assistant (SSMA) |
| Integrity mechanism | OLE2 FAT sector chaining; no application-level checksum |
| Released | 2000 (Access 2000) |
| Latest version | Access 2002-2003 format (last supported in Access 2010) |
| Specification | support.microsoft.com |
ADP conversions
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