A file with .accdc extension is a database package created with Microsoft Access and contains a digitally-signed database. Such type of files are usually created by signing an existing Microsoft Access Database file (i.e. ACCDB) for sending over the internet to other users. The signing of these files are meant to ensure the trust worthiness of these files recevied by end users. Microsoft Access is a relational Database Management system that is used to create and publish databases for use in desktop as well as web-based content management systems. ACCDC files can be opened with Microsoft Access as well as Office 365.
ACCDC File Format - More Information
There are no public specifications available for the ACCDC file format for developer’s reference. A brief analysis of sample ACCDC files show that theses are binary files, with no further details available as such. Since these are generated from the ACCDB files, the internal structure of these ACCDC files is similar to ACCDB files.