What is the DB3 file format?
A .db3 file is a database file created by SQLite, a lightweight and self-contained database engine. SQLite stores data in a structured binary format that can be accessed using SQL. The .db3 extension is a naming convention - it is identical in format to .db, .sqlite, and .sqlite3 files; all share the same 16-byte header SQLite format 3.
An example of a .db3 file is PalmDatabase.db3, which stores personal browsing history. The format requires no server process and runs on Windows, macOS, Linux, Android, and iOS. Tools such as DB Browser for SQLite, the sqlite3 command-line shell, and SQLite Viewer can open .db3 files alongside other SQLite variants.
Security & safety
RISK: MEDIUMA .db3 file is data, not code, so opening it in a viewer is safe. Treat the CONTENTS as sensitive, though: app and browser SQLite databases commonly hold private messages, contacts, history, tokens and location data - don't upload personal databases to online viewers, and prefer a local tool (DB Browser/sqlite3). Never run SQL from an untrusted source against your database (it can DROP/DELETE data). The newest changes may live in companion -wal/-journal files beside the .db3.
Format details
in a nutshellFULL NAMESQLite 3 Database Fileaka SQLite database, SQLite3 database
DEVELOPERSQLite (D. Richard Hipp / SQLite Development Team, public domain)since SQLite 3 file format, 2004
CATEGORYDatabase Files
MIME TYPEapplication/vnd.sqlite3
TYPEBinary single-file SQLite 3 relational database
STANDARDOpen · royalty-free
MAGIC BYTES · FILE SIGNATURE
OFFSET
000102030405060708090a0b0c0d0e0f
HEX
53514C69746520666F726D6174203300
ASCII
SQLite format 3·
A .db3 file is byte-for-byte a normal SQLite 3 database; the first 16 bytes are always "SQLite format 3" + NUL. The .db3 suffix is just a naming convention - the same format is also written as .sqlite, .sqlite3, .db and .s3db. Identify it by this header, not by the extension.
Programs that open DB3 files
Windows4 apps
Navicat for SQlite
Paid Commercial GUI: open the .db3 to manage tables, run queries and export - paid alternative to DB Browser. 
DB Browser for SQLite
Open-source File → Open Database, pick the .db3, then Browse Data to view tables and Execute SQL to query. The standard free viewer/editor.
SQLite (sqlite3 CLI)
Open-source Run 'sqlite3 file.db3', then '.tables' to list tables and SQL queries to inspect/export.
DBeaver
Open-source Create a SQLite connection pointing at the .db3 to browse, query and export across a polished GUI. 
macOS3 apps
DB Browser for SQLite
Open-source Open the .db3 and browse/edit tables; the standard cross-platform viewer.
SQLite (sqlite3 CLI)
Open-source Pre-installed on macOS - 'sqlite3 file.db3' then '.tables' to inspect and '.mode csv'/'.output' to export. 
Linux3 apps
Navicat for SQlite (Linux)
Paid Paid GUI alternative; open the .db3 to manage and export. Use DB Browser if you want free.
DB Browser for SQLite
Open-source Install the sqlitebrowser package and open the .db3 to browse/query visually.
SQLite (sqlite3 CLI)
Open-source 'sqlite3 file.db3' to query; '.dump' to export the whole DB to SQL. Usually pre-installed.
Web1 app
SQLite Viewer (sqliteviewer.app)
Free Drag a .db3 into the browser to inspect tables locally (runs client-side - but don't upload confidential databases). Technical details
deep spec| Encoding | Binary; multi-byte integers in the header and B-tree cells use big-endian byte order |
| MIME type | application/vnd.sqlite3 (also application/x-sqlite3) |
| Magic bytes | 53 51 4C 69 74 65 20 66 6F 72 6D 61 74 20 33 00 at offset 0 (ASCII: "SQLite format 3" + NUL) |
| File header | 100 bytes; stores page size, format version bytes, text encoding, schema version, and other metadata |
| Page size | 512 to 65,536 bytes (must be a power of 2); default is 4,096 bytes since SQLite 3.12.0 (2016) |
| Maximum database size | ~281 TB theoretical (2^31 minus 2 pages at 65,536 bytes each) |
| Storage structure | Single file of fixed-size B-tree pages: root page, per-table B-trees, per-index B-trees, and freelist pages |
| Schema catalog | sqlite_schema table on page 1 records all table, index, view, and trigger definitions |
| Journal and WAL companion files | Rollback journal: .db3-journal; WAL mode adds .db3-wal and .db3-shm alongside the database file |
| Format version bytes | Header offsets 18-19: 1 = rollback journal mode, 2 = WAL mode |
| Encryption | None in the base format; available via SQLCipher or the SQLite Encryption Extension (SEE) |
| Compression | None at page level; applications may store compressed BLOBs inside the database |
| Integrity checking | PRAGMA integrity_check command; optional per-page checksums via the Checksum VFS shim |
| Platform support | Windows, macOS, Linux, Android, iOS, and embedded environments; no server process required |
| Released | SQLite 3 file format, 2004 |
| Latest version | SQLite 3 file format (stable since 2004; magic byte 'SQLite format 3' unchanged) |
| Open standard | Yes · royalty-free |
| Specification | www.sqlite.org |
DB3 conversions
Possible
.DB3 .CSVGUIDE
Yes -- open the .db3 in DB Browser for SQLite (free) and use File > Export > Table to CSV, or run two sqlite3…
How to convert
.DB3 .XLSXGUIDE
Yes - export the table to CSV first, then open and save it as XLSX in Excel or LibreOffice Calc.
How to convert
.DB3 .SQLGUIDE
Yes, a DB3 file can be exported to SQL - the fastest way is one command in the sqlite3 CLI: sqlite3 file.db3…
How to convert
Community Q&A
asked by usersNo questions yet - be the first to ask about DB3 files.
Frequently asked questions
How do I open a .db3 file?
Use the free DB Browser for SQLite (Windows/macOS/Linux): File → Open Database, then Browse Data to view the tables. Or query it with the sqlite3 command line. It's a database, so you browse tables rather than 'read' it like a document.
Is a .db3 file the same as a .sqlite or .db file?
Yes - all three are the same SQLite 3 format (header 'SQLite format 3'). The extension is just a naming convention chosen by the app; any SQLite tool opens all of them, and renaming between them changes nothing.
How do I export a .db3 to CSV or Excel?
Open it in DB Browser for SQLite and File → Export → Table to CSV (one table at a time), then open the CSV in Excel/LibreOffice. DBeaver can export query results directly to XLSX.
Why won't my .db3 open / it says 'file is not a database'?
It may be corrupted, encrypted (e.g. SQLCipher), or not actually SQLite. Check the first 16 bytes - a real SQLite file starts with 'SQLite format 3'. Encrypted databases must be decrypted with their key first.
What is PalmDatabase.db3?
A SQLite .db3 database used by older mobile/Palm devices to store history and personal information. Open it like any SQLite file in DB Browser for SQLite.
Do I need to install a database server to read a .db3?
No - SQLite is serverless and self-contained; the single .db3 file is the whole database, and a tool like DB Browser or the sqlite3 CLI reads it directly with no setup.
References
1SQLite - Database File Formatwww.sqlite.org
2SQLite - Most Widely Deployed Database Enginewww.sqlite.org
