What is the LDB file format?
.ldb is a locking file created by Microsoft Access alongside MDB database files. Its purpose is to coordinate concurrent access and prevent conflicting changes when more than one user opens the same database simultaneously - guarding against data corruption or accidental overwrites.
Internally, .ldb is a binary file made up of fixed-length 64-byte records. Each record stores two 32-byte fields: the null-padded computer name and the Windows user name of a connected client. This lets Access track every active connection to the shared database in real time.
.ldb files are generated automatically the moment Access opens an .mdb database file and are removed just as automatically once the last user closes it. They reside in the same folder as the database and share the same base name - mydb.mdb produces mydb.ldb in the same directory. If Access crashes or is forced closed, an orphaned .ldb may remain on disk and must be deleted manually before the database can be opened cleanly again.
.ldb is the older lock-file format paired with the legacy .mdb format. Starting with Access 2007, the newer .accdb database format uses .laccdb as its equivalent locking companion instead.
Security & safety
RISK: LOWAn .ldb is harmless temporary metadata; it contains no executable code and no sensitive data beyond the computer and Windows user names of current connections. Deleting an .ldb is safe AS LONG AS the database is genuinely closed by everyone - deleting it while the database is open can disrupt the active session. Never delete the .mdb/.accdb (that's your real data). If an .ldb keeps reappearing, a user or a background/automation process still has the database open.
Format details
in a nutshellPrograms that open LDB files
Windows2 apps
Microsoft Access
Paid You don't open the .ldb itself - open the matching .mdb in Access and the lock file is managed/created/removed automatically. 
Notepad / text editor (inspect only)
Open-source Open the .ldb in a text editor only to SEE which computer/user names hold the database open - never edit or save it. Technical details
deep spec| Format type | Temporary binary lock/state file generated alongside a Microsoft Access `.mdb` database |
| Internal structure | Fixed-length 64-byte records, one per active connection |
| Record layout | Each record: 32 bytes null-padded computer name + 32 bytes null-padded Windows user name |
| File creation | Created automatically by Access when an `.mdb` database is first opened |
| File deletion | Deleted automatically by Access when the last connected user closes the database |
| Paired database format | `.mdb` - legacy Microsoft Access Jet database file |
| Modern equivalent | `.laccdb` - the lock file used alongside `.accdb` databases (Access 2007 and later) |
| File naming rule | Same base name and directory as the paired `.mdb` file (e.g., `mydb.mdb` → `mydb.ldb`) |
| File signature | None - no magic bytes; identified solely by file name and location |
| MIME type | application/octet-stream |
| Encoding | Binary; not meaningfully readable as plain text |
| Orphan behavior | If Access crashes, the `.ldb` file may persist on disk; it must be deleted manually before the database can be reopened |
| Multi-user tracking | Tracks all concurrent connections simultaneously; does not restrict the database to a single user |
| Engine origin | Part of the Microsoft Jet Database Engine multi-user record-locking mechanism |
| Released | With Microsoft Access multi-user databases (.mdb era, 1990s); replaced by .laccdb for .accdb databases since Access 2007 |
| Specification | learn.microsoft.com |
LDB conversions
Community Q&A
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