db<>fiddle

What it is

db<>fiddle is a free web site where you write SQL in a series of boxes and run it against a real database server of your choice. As of 2026-09 it supports 14 engines in many versions, including MySQL (5.5 to 9.7), SQL Server (2017 to 2025), PostgreSQL (8.4 up to a 19 beta), Oracle, SQLite, MariaDB, Db2 and DuckDB (source: dbfiddle.uk). Each run produces a link you can share, and fiddles stay private unless you share that link. It is run by Jack Douglas and its code is on GitHub.

Is it worth your time?

Yes, as a tool you keep bookmarked rather than a place to learn. It is the quickest way to:

• test how the same query behaves on PostgreSQL, MySQL and SQL Server, for example LIMIT against TOP, or how NULLs sort;
• try a feature on a newer version than the one you have installed;
• build a minimal example of a problem, with the CREATE TABLE and INSERT statements, to share in a question on a forum or with a teammate.

It is not a replacement for a local database: you cannot load a large sample database, measure performance meaningfully or practise administration tasks there.

Free vs paid

Free. The site shows advertising, and states that it logs only part of your IP address and uses no cookies or tracking scripts (source: dbfiddle.uk, as of 2026-09).

How to use it well

• Put the schema and a few rows in the first boxes and your query in the last, so anyone reading the link sees the whole problem.
• Switch the engine and version from the menu to compare dialects without changing your SQL.
• Keep examples small: the point is to show a behaviour, not to host data.

Alternatives

DB Fiddle (db-fiddle.com) is a similar playground for PostgreSQL, MySQL and SQLite. For SQL Server specifically, db<>fiddle is one of the few free options.

Common questions

Is my data private? Fiddles are private unless you share the link, but do not paste real personal or company data into any public tool.

Can I save my work? Each run gives you a link that recreates it; keep the link.