Format a SQL query, safely.

What "never corrupt input" means here

This formatter tokenizes your query character by character before it reformats anything: strings, comments, quoted identifiers, numbers, operators, and words are each classified first, then only whitespace and line breaks around known clause keywords are changed. A string literal that happens to contain the word SELECT stays exactly as written, quotes and casing intact, because it was tokenized as a string, not as a keyword. If a query has an unbalanced paren or an unterminated string, the tool doesn't try to guess your intent; it passes the malformed part through rather than mangling it further.

A before and after

select u.id, o.total from users u inner join orders o on u.id = o.user_id where o.total > 100 and u.active = 1 order by o.total desc

becomes:

SELECT u.id,
  o.total
FROM users u
INNER JOIN orders o
ON u.id = o.user_id
WHERE o.total > 100
  AND u.active = 1
ORDER BY o.total DESC

CTEs, subqueries, and window functions

A CTE's inner query gets its own indent level relative to the parenthesis it lives inside, so a chain of two or three CTEs stays readable instead of collapsing into one wall of text:

WITH recent AS (
  SELECT *
  FROM events
  WHERE ts > '2026-01-01')
SELECT count(*)
FROM recent

Window functions and their PARTITION BY / ORDER BY clauses stay inside the function's parentheses rather than breaking onto new top-level lines, since a comma inside a function call or argument list is deliberately left inline instead of triggering a new line: ROW_NUMBER() OVER (PARTITION BY dept ORDER BY salary DESC) formats as one readable unit, not a list broken apart by every comma it contains.

Comments and CASE expressions

Line comments (--) and block comments (/* ... */) are recognized as their own token type and never touched beyond being kept on the line they started on. A CASE ... WHEN ... THEN ... ELSE ... END block is tracked as its own nesting level so its internal keywords don't trigger the same line breaks a top-level WHEN would outside a CASE expression, which is a common way naive regex-based formatters break a query that looks fine until you run it.

What this is, and isn't

This is the free, no-key layer of formatting: consistent casing, consistent indentation, one clause per line. It does not rewrite your query's logic, rename anything, or suggest a better join. QueryFlow's Ask panel, using your own API key against a model like Claude Sonnet 5 or GPT-6, can go further: explain what a query does, suggest an index, or rewrite a subquery as a CTE. This tool is the mechanical half of that; Ask is the half that requires actually understanding what the query is for.

Sources

• Standard SQL clause ordering and tokenization behavior implemented and unit-tested against 15 representative queries in this build; no external formatting library used.