Is converting DuckDB to SQLite3 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 SQLite3?

Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real SQLite3 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 SQLite3

Upload a .duckdb or .ddb file and get back a SQLite3 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 SQLite3

Generated from the converter's own SQLite3 type mapping — this is what it actually emits, not an example.

Your data	SQLite3 type
Whole number	BIGINT
Decimal (money)	NUMERIC(10,2)
Floating point	REAL
True / false	BOOLEAN
Date	DATE
Date and time	TIMESTAMP
Short text	TEXT
Long text	TEXT
Binary data	BLOB

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 .sqlite3 name and what carries over

The 3 in sqlite3 is the file format version and the name of the command-line tool, not a property of your conversion. One database file arrives, and the two things worth knowing about it are what it is called and what it leaves behind.

→The file inside the zip is always database.sqlite, whichever spelling brought you to this page. Rename it to database.sqlite3, or to whatever a framework expects, once you have it - the header is what identifies it, never the extension.
→An auto-increment column arrives holding all of its values and nothing that assigns new ones. No AUTOINCREMENT keyword is written, and the column is declared BIGINT rather than exactly INTEGER, so it is not an alias for the rowid either: rows you insert later have to supply their own key.
→Only the rows are transactional. The very first CREATE TABLE runs in autocommit, and everything after it - that table's rows, and every later table - sits in one transaction that commits after the last row. A conversion that fails partway therefore leaves a file holding an empty shell of the first table and nothing else. You never receive that file: the zip is only assembled once the writer has returned.

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 SQLite3

→Columns get real declared types rather than everything being TEXT.
→Primary keys and NOT NULL constraints are preserved.
→A money column is declared NUMERIC(10,2), but that declaration does not stop SQLite’s own numeric affinity from converting the inserted value into a float once it lands, so 19.99 can come back with a rounding tail. Pick the DuckDB target instead when the exact decimal has to survive.

What you get

A ZIP containing database.sqlite. If anything about your data needed a judgement call, a _warnings.txt explains it.

Questions

Is converting DuckDB to SQLite3 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 SQLite3?: Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real SQLite3 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.