Is converting DDB to SQL Server 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 SQL Server?

Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real SQL Server 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 SQL Server

Upload a .duckdb or .ddb file and get back a SQL Server SQL script you can load straight into your database. 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 SQL Server

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

Your data	SQL Server type
Whole number	BIGINT
Decimal (money)	DECIMAL(10,2)
Floating point	FLOAT
True / false	BIT
Date	DATE
Date and time	DATETIME2
Short text	NVARCHAR(255)
Long text	NVARCHAR(MAX)
Binary data	VARBINARY(MAX)

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.

How names and bytes are written

mssql is the short name the drivers use - the ODBC DSN, SQLAlchemy's mssql+pyodbc, the container image. What it produces is ordinary T-SQL text, and the details worth checking before you run it are how it writes names and how it writes raw bytes.

→Identifiers are wrapped in square brackets rather than double quotes, and a bracket inside a source name is turned into an underscore before the wrapping goes on: a column named Order]Date is created as [Order_Date], so a bracket in your data can never close a name early.
→The identifier cap is 128 characters, high enough that almost every source name survives untouched - one that Oracle would have to cut at 30 arrives here whole.
→Binary columns are VARBINARY(MAX) and their values are written as bare 0x hex literals, with no quotes around them and no conversion function wrapped over them.

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 SQL Server

→String literals carry the N prefix, so non-ASCII text survives whatever collation the database uses.
→Timestamps become DATETIME2. T-SQL’s TIMESTAMP is a row-version counter, not a point in time.
→Identity columns are wrapped in SET IDENTITY_INSERT so explicit key values load.
→Statements are separated with GO in batches.

What you get

A ZIP containing dump.sql, plus a README with the exact command to load it. If anything about your data needed a judgement call, a _warnings.txt explains it.

Load this dump into SQL Server:

  sqlcmd -S HOST -U USER -P PASSWORD -d DATABASE -i dump.sql

Notes:

  - Text columns are NVARCHAR and literals carry the N prefix, so
    non-ASCII data survives regardless of database collation.
  - Timestamps are DATETIME2. T-SQL's TIMESTAMP type is a row
    version, not a point in time.

Questions

Is converting DDB to SQL Server 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 SQL Server?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real SQL Server 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.