DuckDB Web Shell
shell.duckdb.org
Run SQL over your own CSV or Parquet file without uploading it
No sign-upOn device
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db-fiddle.com
Run a schema and a query against real MySQL, Postgres or SQLite.
A two-pane SQL scratchpad: schema on the left, query on the right, run it against a specific version of MySQL, PostgreSQL or SQLite and get a shareable link to the result. That link is the reason it exists — it turns 'my query returns the wrong rows' into something someone else can reproduce in one click. Fiddles are public, sessions are short-lived, and it is not somewhere to test against a realistic data volume.
AltFTool does this too
If you would rather not leave the site, SQL Formatter covers the same job here — free, no account, and it runs in your browser.
Open SQL FormatterQuestions
Works the moment the page loads. No account, no email, no trial. Fiddles are public and short-lived, and query runtime is capped.
Yes. DB Fiddle sends your input to its own servers to process it. That is fine for public material; for anything containing personal data, use one of the on-device tools instead.
Fiddles are public and short-lived, and query runtime is capped.
Alternatives
Same category or same task, ordered by how closely they overlap.
shell.duckdb.org
Run SQL over your own CSV or Parquet file without uploading it
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ourworldindata.org
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rawgraphs.io
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tableconvert.com
Converts a table between CSV, JSON, Markdown, SQL and Excel