SQL Diff Checker — Compare Two SQL Queries
Check two SQL queries or scripts for differences. Paste both sides and every added, removed and changed line is highlighted straight away.
To compare two SQL queries online, paste the original into the left pane and the changed query into the right. SQL Diff Checker highlights added, removed and changed lines side by side in your browser — free, no signup, and nothing is uploaded. Turn on Ignore whitespace or Ignore case when formatting or keyword casing is the only difference.
Check two SQL statements
How to compare two SQL queries online
- Paste both sides. Put the original query or script in the left pane and the changed version in the right.
- Read the highlights. Removed lines show on the left, added lines on the right. The diff uses the Myers algorithm git uses and updates as you type.
- Cut formatting noise. Enable Ignore whitespace or Ignore case when indentation or keyword casing is the only difference.
- Stay private. Script and query diffs run in your browser — nothing is uploaded. For SQLite .db files, use the database compare (free up to 50MB / 200,000 rows per table).
When to use a SQL query diff online
- Review a pull-request query change without hunting for the edited clause by eye.
- Diff a stored procedure or view definition from staging against production.
- Confirm a formatter or refactor only changed whitespace (enable Ignore whitespace / Ignore case).
- Compare two migration files or multi-statement scripts line by line in the browser — free, nothing uploaded.
What a SQL diff checker is for
Most SQL changes are small edits to something long — an extra join condition, a column added to a SELECT list, a WHERE clause that quietly gained an AND. Reading two 200-line queries side by side and spotting that by eye is slow and unreliable. A diff checker does the comparison mechanically so you can see the change rather than hunt for it.
Common cases this handles well
Reviewing a query change. Someone edited a report query and the numbers moved. Diff the old and new versions to find the clause responsible.
Comparing environments. Dump a stored procedure or view definition from staging and from production, paste both in, and see where the two have drifted apart.
Checking a migration. Compare the schema your migration was written against with the schema actually deployed, before the migration runs rather than after.
Reformatting safely. After running a query through a formatter, diff it against the original with “Ignore whitespace” enabled to confirm the formatter only moved whitespace and did not change logic.
Why the results stay on your machine
Query text often contains table names, column names, business logic and sometimes literal values from real records. Pasting that into a site that uploads it to a server is a genuine risk, and one that is easy to avoid: this checker does the comparison in your browser with JavaScript. No request is made, so there is nothing to leak, log or retain.
Frequently asked questions
How do I compare two SQL queries online?+
Paste the original query into the left pane and the changed query into the right. SQL Diff Checker highlights added, removed and changed lines side by side with a Myers diff (the same algorithm git uses). Turn on Ignore whitespace or Ignore case when only formatting or keyword casing differs. Free, no signup, and nothing is uploaded — the comparison runs in your browser.
Why does the checker show a whole line as changed when I only edited one word?+
The comparison works line by line, which is how git and most code review tools work. If you reformatted a query, turn on "Ignore whitespace" so that indentation and spacing changes are filtered out and only real differences remain.
Can I check two queries that differ only in keyword casing?+
Yes. Enable "Ignore case" and SELECT and select will be treated as identical. This is useful when comparing a formatted query against one written in a different house style.
Does the checker validate SQL syntax?+
No. It compares text and reports what changed. It does not parse or execute your SQL, which is why it works safely with any dialect and with fragments that are not runnable on their own.
Can I compare stored procedures, views, or functions online?+
Yes. Export each definition as text and paste both into the panes. PostgreSQL: pg_get_functiondef() / pg_get_viewdef(). MySQL: SHOW CREATE PROCEDURE / SHOW CREATE VIEW. SQL Server: OBJECT_DEFINITION() or sp_helptext. The checker is a Myers line diff in your browser — free, no signup, nothing uploaded — and works with any dialect because it does not execute the SQL.
How is SQL Diff Tool different from sqlformat.io, Aiven SQL Compare, or Text Compare?+
SQL Diff Tool compares SQL scripts side by side in your browser for free, with nothing uploaded. Unlike many online SQL compare tools that only diff text, it also compares SQLite .db files table-by-table (free up to 50MB and 200,000 rows per table) and supports MySQL and schema-focused pages. Paid plans cover larger .db files on our servers.
Is SQL Diff Tool free, and do my SQL scripts leave my browser?+
Yes for text diffs: paste two scripts or queries and they are compared locally in your browser — free, no signup, nothing uploaded. SQLite schema text diffs work the same way. Free .db file compares stay in the browser up to 50MB / 200,000 rows per table; larger files use a paid server compare.
Can SQL Diff Tool compare SQLite databases, not just SQL text?+
Yes. On /sqlite-diff you can paste two .schema exports or upload two .db files for a table-by-table row and schema diff. Schema paste is free in-browser. .db compares are free up to 50MB and 200,000 rows per table; larger files need a paid account.
What's the best free online SQL diff checker for MySQL, PostgreSQL, and SQL Server?+
SQL Diff Tool works with any dialect (MySQL, PostgreSQL, SQL Server, SQLite). Paste the original into the left pane and the changed version into the right to see added, removed, and changed lines. Ignore whitespace and Ignore case options help when only formatting differs. Free for script and query diffs with nothing uploaded.
What is a free online SQL diff tool?+
A free online SQL diff tool lets you paste two SQL scripts or queries and see every added, removed and changed line side by side in the browser. SQL Diff Tool does that with a Myers diff, works with any dialect (MySQL, PostgreSQL, SQL Server, SQLite), needs no signup, and uploads nothing for text compares. It can also compare two SQLite .db files table by table (free up to 50MB and 200,000 rows per table; larger files need a paid account).