What is the MDE file format?
.mde is a compiled database file format for Microsoft Access, created from an .mdb source database using the "Make MDE File" command. Where the original .mdb stores editable Visual Basic for Applications (VBA) source code alongside tables, queries, and views, the .mde compiles that VBA to p-code and strips the editable source entirely.
Access database formats can be divided into two groups:
.mde- binary compiled format (design-locked).mda- Access add-in source files
Both formats store code written in Visual Basic for Applications. .mde compiled files cannot be opened to view the source code or modify it, and forms, reports, and modules are locked out of Design view. An .mdb file serves as the base for producing an .mde.
The result is a distribution-ready database: users can run queries, enter data, and navigate forms, but cannot alter the underlying logic or interface design. Because the conversion is one-way, it is not possible to recover the editable source from an .mde - always retain the original .mdb. The .mde format applies only to legacy Jet-engine databases (Access 97 through 2003); Access 2007 and later replaced it with .accde for the newer .accdb format.
Security & safety
RISK: MEDIUMAn .mde runs compiled VBA code that you cannot inspect, so only run MDE applications from a source you trust - Access opens databases with macros/code disabled by default (Trust Center / yellow security bar); leave them disabled unless you trust the sender. The data tables themselves are inert. Don't rely on the locked design or any legacy Jet 'database password' for security - the data is readable by export tools regardless.
Format details
in a nutshell- ArchiCAD Add-On (GDL/extension module) - Some Graphisoft ArchiCAD add-ons historically used the .mde extension for loadable extension modules - unrelated to Access.
Programs that open MDE files
Windows3 apps
Microsoft Access
Paid Double-click the .mde to open and run it (forms, reports, data). You cannot enter Design view - that's by design. Matching Access version/bitness needed. 
MDB Viewer Plus
Free Portable freeware - open the .mde to view/export the DATA (tables) to Excel/CSV. Won't run forms or recover code. 
Microsoft Access Runtime
Free Free runtime to RUN an Access .mde application without owning full Access - ideal for distributed MDE apps. Cannot design. Technical details
deep spec| Developer | Microsoft |
| File encoding | Binary, little-endian Jet page structure |
| MIME type | application/x-msaccess |
| Magic bytes | 00 01 00 00 then "Standard Jet DB" at offset 4 (identical to .mdb on disk) |
| VBA handling | VBA compiled to p-code; editable source stripped during Make MDE File conversion |
| Design lock | Forms, reports, and modules locked - cannot be opened in Access Design view |
| Reversibility | One-way conversion; cannot decompile or recover an editable .mdb from an .mde |
| Source format | Built from an Access 97-2003 .mdb via Tools → Database Utilities → Make MDE File |
| Typical file size | 500 KB - 200 MB (data plus compiled code and embedded objects) |
| Encryption | Optional legacy Jet database password (weak XOR-based); VBA is locked by source removal, not by encryption |
| Integrity | Jet page-level checksums; Compact & Repair corrects minor corruption |
| Operating system | Windows only |
| Version sensitivity | Must be opened with the same Access version and bitness it was compiled with |
| Successor format | ACCDE (for .accdb databases, Access 2007 and later) |
| Related formats | .mdb (source), .mda (add-in), .mdw (workgroup), .ldb (lock file) |
| Released | 1997 (Access 97 - 'Make MDE File' feature) |
| Latest version | MDE remained the compiled format for MDB-based databases through Access 2003; succeeded by ACCDE for ACCDB in Access 2007 |
| Specification | learn.microsoft.com |
MDE conversions
Community Q&A
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