Is converting DDB to XLSX free?

Yes. Files up to 10MB convert free with no account. There is a limit of five conversions per day per IP address.

Will my DDB data keep its types in XLSX?

Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real XLSX types rather than everything becoming text. The mapping table above shows exactly what you get.

Do you store my file?

No. The file is written to a temporary directory, converted, and the directory is deleted as soon as your download has been sent.

Convert DDB to XLSX

Upload a .duckdb or .ddb file and get back a XLSX file. Types are preserved rather than flattened to text. Free, no registration, up to 10MB.

1Upload your file

Click to upload or drag and drop

CSV, Excel, SQLite, SQL, DBF (max 10 MB)

2Choose target format

How your data is typed in XLSX

Generated from the converter's own XLSX type mapping — this is what it actually emits, not an example.

Your data	XLSX type
Whole number	number
Decimal (money)	number
Floating point	number
True / false	boolean
Date	date
Date and time	date
Short text	text
Long text	text
Binary data	hex text

Working from a .ddb file

.ddb is the short form of the DuckDB extension, and DuckDB itself does not care what you call a database file. The uploader does: it routes on the extension alone, so the name you saved under decides which reader ever sees the file.

→.ddb and .duckdb both reach the DuckDB reader and are read identically. Nothing inside the file records which of the two you chose - the storage version is in the header, the name is not.
→One file is this format's whole promise, so make sure it really is one file before you send it: closing the DuckDB CLI cleanly, or running CHECKPOINT first, folds the write-ahead log back into the database itself.
→A file with no extension at all, which DuckDB is perfectly happy to create, is not recognised as anything and is refused before it is read.

Sheet names and cell types

The workbook is generated rather than exported out of Excel, so every choice in it is one the converter made. The two that show up the moment you open the file are what the sheet is called and what type each cell turned out to be.

→The sheet takes the table's name cut to 31 characters, which is Excel's own limit for a tab, while the workbook file keeps the name in full - so a long table name is complete in the file name and shortened on the tab inside it.
→Dates and timestamps become genuine date cells, formatted yyyy-mm-dd and yyyy-mm-dd h:mm:ss, rather than strings that merely look like dates. Sorting and date arithmetic work on them with no conversion step first.
→A text column of digits stays text: a value like 01234 is written into a string cell, and Excel shows it as it was stored instead of dropping the zeros the way it does when the same data is opened from a CSV.

Reading DDB

→Types, primary keys and NOT NULL constraints are read from the database.
→The file is opened read-only, so your upload is never modified or upgraded in place.

Writing XLSX

→One file per table. Booleans stay booleans and numbers stay numbers.
→Excel has no fixed-point type, so decimals become numbers — use a database target if exactness matters.

What you get

A ZIP containing <table>.xlsx. If anything about your data needed a judgement call, a _warnings.txt explains it.

Questions

Is converting DDB to XLSX free?: Yes. Files up to 10MB convert free with no account. There is a limit of five conversions per day per IP address.
Will my DDB data keep its types in XLSX?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real XLSX types rather than everything becoming text. The mapping table above shows exactly what you get.
Do you store my file?: No. The file is written to a temporary directory, converted, and the directory is deleted as soon as your download has been sent.