Code

Optimize SQL queries with AI

Paste your SQL query and get an optimized version with performance notes and index recommendations.

For the best results: Paste the slow query and describe your table sizes and indexes. The AI rewrites it for performance and explains why.

AI can make mistakes. Check important information before relying on it.

FREE · PRIVATE · NO SIGN UP REQUIRED · NO ACCOUNT NEEDED

What is SQL Optimizer?

SQL Optimizer is a free AI coding assistant that takes a SQL query and returns an optimized version with performance notes and index recommendations. Each request is handed to a code-specialized model chosen for the task, returning working code, bug fixes, and explanations in any programming language in seconds. You paste and go, with no login and nothing to install, and the code you share is not retained once the session ends.

✦Paste code and go, no login, nothing to install
✦Code-specialized models are selected per request automatically
✦Your code is not retained after the session ends

Models: It routes across strong coding models including Llama, Gemini and Mistral families, picking the best available one per request. The exact model used is shown after every response.

See it in action

A reporting query that lists this year's paid orders has crept up to several seconds and is timing out the dashboard.

What you type

SELECT * FROM orders WHERE YEAR(created_at) = 2025 AND status = 'paid';

What you get

-- Optimized SELECT id, customer_id, total, created_at FROM orders WHERE created_at >= '2025-01-01' AND created_at < '2026-01-01' AND status = 'paid'; -- Recommended index CREATE INDEX idx_orders_status_created ON orders (status, created_at); Wrapping created_at in YEAR() made the predicate non-sargable, so the engine scanned every row. A half-open date range lets it seek the index instead, and selecting named columns avoids hauling back unused blobs.

Tip: Any function wrapped around an indexed column (YEAR, LOWER, DATE) throws away the index and forces a full scan. Rewriting it as a range or storing a computed column is usually a bigger win than adding hardware.

Use cases

What people use it for

Rescue the report query that started timing out once the orders table got big.

Sanity-check a five-join query before it ships inside a nightly batch job.

Find the missing index when one dashboard filter takes seconds to load.

Who uses SQL Optimizer?

Backend engineers

speeding up a slow endpoint by reworking the query behind it and adding the index it was missing

Analysts on big tables

cutting a report query that scans millions of rows down to something that returns before the meeting starts

Accidental DBAs

the developer who owns the database by default, looking for why a nightly job crept from minutes to hours

How it works

1Paste your code or describe what you need built.
2A code-specialized model writes, fixes, or explains it.
3Copy the code out, or ask follow-ups to iterate on it.

Tips for the best results

Paste your table sizes, existing indexes and the EXPLAIN plan along with the query, since the same SQL performs very differently on a thousand rows versus a hundred million.
Name your database engine, because index types, query planners and even the syntax for hints differ between PostgreSQL, MySQL, SQL Server and the rest.
Say what slow means for you; a dashboard that must feel instant needs different trade-offs than a nightly batch job that just has to finish.
Do not blindly add every suggested index; each one speeds reads but slows writes and uses space, so add them one at a time and measure.
Verify the optimized query returns identical results on real data before shipping it, as a rewrite that is faster but subtly wrong is worse than a slow correct one.

FAQ

Frequently asked questions

Will the optimized query return exactly the same results?

That's the contract, but verify it yourself, rewrites can shift semantics in subtle ways, especially around NULL handling, duplicate rows and outer joins. Run the original and optimized versions against the same test data and compare row counts and totals before swapping anything into production.

How can it judge performance without access to my database?

It reasons from well-established patterns: predicates that defeat indexes, SELECT * pulling unneeded columns, joins that could filter earlier, subqueries better written as joins. For advice grounded in your reality, paste the EXPLAIN or execution-plan output and rough table sizes alongside the query, that context changes the recommendations.

Should I create every index it suggests?

No, treat them as candidates, not instructions. Every index accelerates certain reads while slowing every write to that table and consuming storage. Add the one targeting your slowest predicate first, measure the difference, and stop when the query is fast enough. Databases accumulate junk indexes exactly this way.

Does my database engine matter?

Considerably. PostgreSQL, MySQL, SQL Server and the cloud warehouses optimize differently and support different index types, so the same rewrite can help on one engine and do nothing on another. Name your engine and version up front so the notes and recommendations apply to what you're actually running.

What should I paste besides the query?

Table schemas, approximate row counts, existing indexes and what 'slow' means in your case, three seconds on a dashboard, or an hour in a batch window. The query alone gets generic tuning; the surrounding context gets recommendations shaped to your workload rather than a checklist of best practice.

Is this SQL optimizer free to use?

Yes. Paste a query and get an optimized version with performance notes for free, with no account, sign-up or payment. There is no limit behind a login. It reasons about your query structure rather than connecting to your database, so treat its suggestions as a strong starting point you confirm with your own EXPLAIN output.

Can it read my EXPLAIN or query plan?

Yes, and it helps a lot. Paste the output of EXPLAIN or EXPLAIN ANALYZE alongside the query and the tool can point to the full table scans, expensive sorts and misused indexes the plan reveals. Without it the advice is based on the query text alone, so the plan makes the recommendations far more precise.

Will it explain why my query is slow?

Yes. Alongside the rewritten query you get an explanation of what was costing time, such as a missing index, a function wrapped around an indexed column, an unnecessary subquery or a join in the wrong order, and why the new version avoids it. That reasoning is often more valuable than the rewrite itself.

What are the usage limits?

Code tools are text tools, so they are unmetered during the current free launch phase, iterate on a bug or generate as many drafts as the work needs. A short per-minute limit guards against scripted abuse only. Paid plans with higher limits and priority model access are coming soon.

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