What is the FDB file format?
The .fdb file extension is used with database files native to Firebird software, a cross-platform system designed for SQL database administration on Windows, Unix, macOS, and Linux operating systems.
.fdb files store Firebird database content in a single self-contained binary file. They contain logically related database records - organized into tables, indexes, and BLOB pages - along with stored procedures, triggers, and views. Firebird adopted .fdb as its standard extension after its 2000 open-source fork from Borland InterBase, replacing the older .GDB format which had conflicted with Ghost backup software.
Internally, a .fdb file uses a versioned ODS (On-Disk Structure) layout. The header page records the ODS version and page size; there is no ASCII magic signature, so the file must be identified by a Firebird-aware tool rather than by byte inspection alone. Default page size is 8 KB in Firebird 3.0+ releases (up from 4 KB in Firebird 2.x).
Firebird operates in embedded (direct file access) or client-server mode over TCP/IP on port 3050. Full ACID-compliant transactions use MVCC (multi-version concurrency control) for row-level isolation. Database backups are saved as .FBK files using the gbak command-line utility.
Security & safety
RISK: MEDIUMA Firebird .fdb is data, not an executable, so the file itself won't run code - but databases warrant care. (1) An .fdb can be large and may contain sensitive personal/business data, so treat a received database as confidential. (2) Firebird databases are version-sensitive (ODS): opening with the wrong server version can fail or, with the wrong tools, risk corruption - always work on a COPY. (3) Default Firebird installs historically shipped with the well-known SYSDBA/masterkey credentials; an .fdb relying on that is a security weakness. Avoid sketchy 'FDB viewer' downloads that bundle PUPs - use the official Firebird tools, DBeaver, FlameRobin, or IBExpert.
Format details
in a nutshell- Visual FoxPro database - Legacy Microsoft FoxPro database container (FoxPro discontinued, last release 2007); needs FoxPro-compatible tools or a converter.
- Extensis Portfolio catalog - Digital-asset-management catalog (thumbnails + metadata) created and opened by the Extensis Portfolio app.
Programs that open FDB files
Windows4 apps
FlameRobin
Open-source Install Firebird, then in FlameRobin register the .fdb (server localhost, path to file, user/password) to browse tables and run SQL. Free, lightweight.
DBeaver
Open-source Create a Firebird connection pointing at the .fdb; DBeaver (Community, free) browses tables and exports data to CSV/Excel/SQL.
IBExpert
Freemium Professional Firebird/InterBase admin tool; connect to the .fdb to view, query, and manage the database. Free personal edition.
Full Convert (Spectral Core)
Paid Open the Firebird .fdb and migrate/export it to another database or to CSV/Excel. Paid; useful for one-off data extraction. 
macOS1 app
DBeaver
Open-source Free cross-platform client; create a Firebird connection to the .fdb to browse and export the data. 
Linux2 apps
DBeaver
Open-source Install Firebird and DBeaver, add a Firebird connection to the .fdb, and query/export the tables.
Firebird isql (CLI)
Open-source Use the bundled 'isql' tool: isql -user SYSDBA -password ... /path/to/database.fdb, then run SQL. Technical details
deep spec| Format type | Single-file paged binary relational database |
| Developer | Firebird Project (forked from Borland InterBase) |
| Platform support | Windows, Linux, macOS, Unix (cross-platform server and embedded) |
| ODS versioning | On-Disk Structure version stored in file header; ODS 11 (Firebird 2.x), ODS 12 (Firebird 3.0), ODS 13 (Firebird 4.0) |
| Page size | 4 KB (Firebird 2.x default), 8 KB (Firebird 3.0+ default); configurable up to 32 KB at creation time |
| MIME type | application/octet-stream |
| File signature | No ASCII or hex magic bytes; identified by ODS header at byte offset 0 via Firebird tooling |
| Deployment modes | Embedded (direct file access) and Classic/SuperServer/SuperClassic (multi-user client-server) |
| SQL support | Firebird SQL dialect (SQL-92/99 extensions); stored procedures, triggers, views, UDFs |
| BLOB support | Text and binary large objects stored in dedicated internal BLOB pages |
| Remote protocol | TCP/IP on port 3050 (default); Named Pipes on Windows |
| Transaction model | ACID-compliant with MVCC (multi-version concurrency control); row-level isolation |
| Character sets | Per-column charset declarations; UTF8, ISO8859_1, WIN1252, UNICODE_FSS supported |
| File size limit | Constrained by OS file system; multi-file secondary databases can be attached for larger datasets |
| Related extensions | .gdb (legacy InterBase format), .fbk (Firebird backup), .ib (InterBase) |
| Released | Firebird forked from Borland InterBase when it was open-sourced in 2000; InterBase .gdb/.fdb lineage from the 1980s |
| Open standard | Yes · royalty-free |
| Specification | firebirdsql.org |
FDB conversions
Community Q&A
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