Convert DuckDB to CSV
Upload a .duckdb or .ddb file and get back a CSV file. Types are preserved rather than flattened to text. Free, no registration, up to 10MB.
Click to upload or drag and drop
CSV, Excel, SQLite, SQL, DBF (max 10 MB)
How your data is typed in CSV
Generated from the converter's own CSV type mapping — this is what it actually emits, not an example.
| Your data | CSV type |
|---|---|
| Whole number | text (CSV has no types) |
| Decimal (money) | text (CSV has no types) |
| Floating point | text (CSV has no types) |
| True / false | text (CSV has no types) |
| Date | text (CSV has no types) |
| Date and time | text (CSV has no types) |
| Short text | text (CSV has no types) |
| Long text | text (CSV has no types) |
| Binary data | text (CSV has no types) |
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 shape of the CSV files you get
CSV is where the type information stops, so what is left to describe is the file itself: how a row is terminated, which fields are quoted, and how a value that used to have a type is spelled out as characters.
- →Rows end with a carriage return and a line feed, the RFC 4180 ending, while a newline inside a quoted field stays the single character it always was. The encoding is UTF-8 with no byte-order mark in front of it.
- →Quotes go on only where they are needed - a field holding a comma, a double quote or a newline - and a quote inside a field is doubled rather than escaped with a backslash. Every other field is written bare.
- →Decimal values are written digit for digit and never through a floating-point number, so a money column that was exact in the source is still exact in the file. Booleans are written lower case, as true and false, which is the spelling this converter's own reader takes back as a boolean.
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 CSV
- →One file per table, with a header row.
- →NULL is written as an empty field, never the word "None".
- →Binary data is written as hex, which is reversible.
What you get
A ZIP containing <table>.csv. If anything about your data needed a judgement call, a _warnings.txt explains it.
Questions
- Is converting DuckDB to CSV 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 CSV?
- Yes — that is the point. Whole numbers, decimals, dates and booleans are mapped to real CSV 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.