Is converting DuckDB to MariaDB 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 MariaDB?

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

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

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

Your data	MariaDB type
Whole number	BIGINT
Decimal (money)	DECIMAL(10,2)
Floating point	DOUBLE
True / false	TINYINT(1)
Date	DATE
Date and time	DATETIME
Short text	VARCHAR(255)
Long text	LONGTEXT
Binary data	LONGBLOB

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.

What MariaDB gets, and how it differs

MariaDB and MySQL are close enough here that one dialect serves both, and picking MariaDB does not select a different code path: the script is byte for byte the one a MySQL conversion produces. The differences worth flagging are in what you do with it.

→The README packed beside the script names both engines in its load command, because the invocation is the same either way - the file is piped into a client rather than executed by the server.
→The CREATE DATABASE line in that README asks for utf8mb4_unicode_ci and not for utf8mb4_0900_ai_ci, which is MySQL 8's default. MariaDB has never implemented the 0900 collations, and unicode_ci is the one both engines have.
→Date-and-time columns are declared DATETIME rather than TIMESTAMP, so what loads is the wall-clock value the source held. No session time zone is applied on the way in, and none is applied when you read it back out.

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 MariaDB

→Tables are created as InnoDB with utf8mb4, so emoji and CJK text survive the load.
→Backslashes are escaped, because MySQL treats them as escape characters by default.
→Text columns of unknown length become TEXT rather than a guessed VARCHAR that could truncate your data.
→Inserts are batched, and identifiers are capped at MySQL’s 64-character limit.

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 MySQL or MariaDB:

  mysql -u USER -p DATABASE < dump.sql

Create the database first if it does not exist:

  mysql -u USER -p -e "CREATE DATABASE DATABASE CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;"

Questions

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