Is converting DuckDB to T-SQL 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 DuckDB data keep its types in T-SQL?

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

Upload a .duckdb or .ddb file and get back a T-SQL 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 T-SQL

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

Your data	T-SQL 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 .duckdb file

DuckDB keeps an entire analytical database in one file, with real types behind it - decimals that are decimals, and integers wide enough to be worth checking before you move them somewhere narrower.

→Only the main schema is read. Tables created in another schema, or in a second database attached at query time, are not part of the conversion.
→Views in main are read as though they were tables, so a view's rows are materialised into the target rather than skipped.
→HUGEINT is the one type with nowhere to go: no target here has a 128-bit integer, so those columns are carried across as text rather than silently truncated.
→A DuckDB process that was killed leaves a .duckdb.wal sidecar holding everything it had not checkpointed yet. Upload the database on its own and it opens with no error and no tables at all - send the .wal file alongside it, or checkpoint before you copy the database out.

The T-SQL the script actually uses

T-SQL is the language rather than the product, and it is exactly where a generic ANSI SQL script fails against SQL Server. Two of those differences are why this target has a dialect of its own instead of reusing the shared one.

→Date and timestamp values are written as ordinary quoted strings. The ANSI typed literal - the word DATE in front of a quoted date - is not T-SQL, and the server rejects it, which on its own is enough to make a portable script fail to load.
→GO is not a statement in the language at all. sqlcmd, SSMS and Azure Data Studio read it as a batch separator and the server never sees it, so a driver handed the whole file as one string chokes on it: run the file through one of those clients, or split the text on its GO lines and send the pieces in order down the same connection.
→Rows are written 500 to a statement, comfortably under the 1000-row ceiling T-SQL puts on a single VALUES list. That ceiling is what makes a script built around one statement per table fail on any table worth converting.

Reading DuckDB

→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 T-SQL

→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 DuckDB to T-SQL 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 DuckDB data keep its types in T-SQL?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real T-SQL 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.