Software & Apps File Types What Is an ACCDR File? by Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated on October 28, 2019 ACCDR Files. Lifewire File Types Design Cryptocurrency MS Office Windows Linux Google Drive Apps File Types Backup & Utilities View More Tweet Share Email A file with the ACCDR file extension is a Microsoft Access Runtime Application file. It's just a read-only, locked-down version of an ACCDB file that results in the database opening in run-time mode. How ACCDR Files Work If an ACCDR file is renamed to have the .ACCDB extension, it restores full write functions so you can make changes to it. If the opposite is done, it effectively locks down an ACCDB database file so that it's no longer editable. ACCDR files are superior over ACCDB files in that, while they're still able to open and be read, they can't accidentally be manipulated. However, they don't provide the same protection as ACCDE files. ACCDR files have nothing to do with CDR files. How to Open an ACCDR File ACCDR files are opened using Microsoft Access. If you, or someone you're sending an ACCDR file to, doesn't have Microsoft Access installed, the ACCDR file can still be opened with the free Microsoft Access Runtime. This isn't a free version of Microsoft Access in its entirety, but it is an option you have for viewing ACCDR files without needing the full Access software installed. If you're not sure which file to choose on the Microsoft Access Runtime download page, learn how to tell if you have Windows 64-bit or 32-bit. The 32-bit and 64-bit versions are called AccessRuntime_x86_en-us.exe and AccessRuntime_x64_en-us.exe, respectively. If you find that an application on your PC does try to open the ACCDR file but it's the wrong application or if you would rather have another installed program open ACCDR files, see how to change the default program for a specific file extension guide for making that change in Windows. How to Convert an ACCDR File The easiest way to convert an ACCDR file to ACCDB is to of course just rename the extension from .ACCDR to .ACCDB. Renaming a file like this isn't possible in Windows until you make a small change to the way the files are displayed in File/Windows Explorer. Showing a file's extension can be done by searching for the Folder Options applet in the Control Panel. Once there, under the View tab, uncheck the Hide extensions for known file types option. This will let you see the .ACCDR extension after the file name so that you can rename it to .ACCDB. Because an ACCDR file is really an ACCDB file, after renaming it as such, you can use any file converter that supports the ACCDB format to convert it to something else. Microsoft Access is one example of software that can save an open ACCDB file to a brand new format You can't normally just rename a file to the format you want it to be in and expect that new file to work properly. For example, renaming an MP4 file to MP3 doesn't suddenly turn the video file into an audio file. However, given what an ACCDR file actually is (just a renamed file), you can simply rename it so the extension is .ACCDB, and have it function the exact same way an ACCDB file would.