Query Studio
Translate SQL between 18 database dialects
Translate, format, validate and understand SQL & NoSQL across 18 database dialects. Free, no login, nothing stored.
Convert a query from one database dialect to another.
New · Workbench
Run SQL against your own files
Everything above works on a query as text. The Workbench runs it: drop a multi-gigabyte CSV, JSON, Parquet or log file and query it for real, with DuckDB running inside your browser tab. No upload, no row limit, no account — and the free apps for Windows, macOS, Linux and Android have no file size limit at all.
Everything in one studio
Eight free tools for reading, converting and cleaning up your queries — every result computed instantly, no AI and no sign-up.
Universal Translator
Convert queries across 18 dialects — identifiers, row limiting, null handling, current-timestamp and OFFSET paging — plus SQL to MongoDB.
Explain Query
See a SELECT walked through its true logical execution order, clause by clause.
Visual Execution
Animate rows flowing through JOIN, WHERE, GROUP BY, ORDER BY and LIMIT.
Performance Analyzer
A 0–100 score with severity-ranked warnings for SELECT *, cartesian joins, non-sargable filters and more.
Query Optimizer
Concrete rewrite suggestions and CREATE INDEX candidates derived from your WHERE and JOIN columns.
Formatter
Beautify or compress SQL with dialect-aware keyword casing and indentation.
Validator
Real AST parsing plus best-practice checks for risky and non-portable patterns.
Schema Diagrams
Turn CREATE TABLE statements into an ER diagram with foreign-key connectors.
18 supported databases
From the big relational engines to cloud warehouses and NoSQL query languages. See what each one supports.
SQL
NoSQL / Other
Popular query conversions
The translations developers reach for most. Pick a pair in the translator above to try any of them.
Query Studio vs SQLines, jOOQ Translate and the rest
The other tools for this job and where each one stops. Checked in August 2026. Two of these are better than this one for a full schema migration, which is said plainly below rather than left out.
SQLines Online
The best-known free web SQL converter, and the most direct comparison.
- Where it stops
- It targets whole-schema and script conversion — DDL, stored procedures, triggers — which is a much larger job than a query, and its output usually needs review before it runs.
- What Query Studio does
- Query Studio is query-first: paste a SELECT, get a runnable SELECT. It also explains the execution order, scores the query for anti-patterns and suggests indexes, none of which a converter does.
- Where they’re better
- If you need to move an entire schema, including procedural code, SQLines is doing the bigger job and this tool is not a substitute for it.
jOOQ Translate
A free web translator built on the jOOQ parser, which is a genuinely excellent piece of engineering.
- Where it stops
- It is a translation front end for the parser and does not analyse, explain or diagram your query.
- What Query Studio does
- Translate, Explain, Visualize, Analyze, Optimize, Format, Validate and ER diagrams, chained together so a result feeds straight into the next tool.
- Where they’re better
- For pure dialect translation on complex vendor SQL, jOOQ's parser is more thorough than anything here. If a translation looks wrong, it is worth a second opinion.
AWS Schema Conversion Tool
Amazon's migration tool, aimed at moving schemas and application SQL onto AWS databases.
- Where it stops
- It is a desktop application you install and configure, built around a full migration project rather than a single query, and its conversions are oriented towards AWS targets.
- What Query Studio does
- A web page. Paste a query, get an answer, close the tab.
- Where they’re better
- For an actual enterprise migration with assessment reports and application code scanning, SCT is the serious tool and a web translator is not.
An AI chatbot
Increasingly the default answer, and worth addressing directly.
- Where it stops
- It is non-deterministic — the same query can produce different output on different runs — it is rate-limited, and when it is wrong it is wrong fluently, which is the failure mode that actually costs you time.
- What Query Studio does
- Real SQL parsers and rule engines. The same input gives the same output every time, instantly, with no limit and no plausible-sounding invention.
- Where they’re better
- A model will attempt stored procedures and business logic, which this tool refuses outright. Just verify everything it gives you.
What Query Studio will not do
It translates SQL syntax, deterministically and without AI. Being clear about where that stops is more useful than pretending it doesn’t — and if you are midway through a real migration, this is probably the most important section on the page.
Stored procedures, functions and triggers
Procedural code — PL/pgSQL, T-SQL procedures, MySQL routines — is a different language in every engine, with different control flow, error handling, variable declaration and transaction semantics. Query Studio translates queries, not programs. These have to be ported by hand.
Anything that depends on data rather than syntax
Whether a value fits the target type, whether a date is real, whether a text column's contents are valid UTF-8 — none of that is visible in the query. A translation can be syntactically perfect and still fail on the first row of the import.
Vendor-specific extensions
PostGIS geometry, MySQL spatial functions, SQL Server's FOR XML and hierarchyid, BigQuery's nested/repeated model, Snowflake's time travel. Where there is no equivalent concept, there is no translation — only a redesign.
Performance characteristics
A converted query is correct, not fast. Index strategy, partitioning, distribution keys and statistics differ per engine, and a query that was well-tuned for the source is merely valid on the target. Run the Analyze and Optimize tabs on the output.
Transaction and isolation semantics
Default isolation levels, locking behaviour and whether DDL is transactional all vary. Two engines can run identical SQL and disagree about what is visible to a concurrent reader.
Frequently asked questions
Is this an AI SQL converter?
No, and that is deliberate. The query is parsed into a syntax tree, transformed, and printed in the target dialect — a deterministic rewrite, so the same input always gives the same output. Most free SQL converters are now a prompt wrapped around a language model, which means the result can look correct and quietly return different rows, and you have no way to tell from the output. A parser either understands your query or says it does not.
Does my SQL get uploaded to a server?
No. Every engine here is JavaScript running in your browser tab, so your query never leaves your machine. You can verify it: open your browser's network tab and translate something, and no request carries your SQL. It also keeps working with the network disconnected. This is the reason people paste production schemas into it, and it is not something a server-side or AI-backed converter can offer.
Is there a limit on how many queries I can convert?
No. No per-hour cap, no daily quota, no account, no trial, no paid tier. Several comparable tools meter you at around 30 conversions an hour because each one costs them a server call; nothing here runs on a server, so there is nothing to meter.
Can I use it offline?
Yes. Once the page has loaded, everything runs locally — translate, format, validate, explain, optimise and diagram all work with no connection. The large-file Workbench does too, and the desktop apps ship the whole engine so they never need a connection at all.
How do I convert a MySQL query to PostgreSQL?
Select MySQL as the “From” dialect and PostgreSQL as the “To” dialect, paste your query, and press Translate. Query Studio rewrites the parts that differ between the two databases — backtick identifiers become double quotes, IFNULL becomes COALESCE, and MySQL’s LIMIT/OFFSET is kept in PostgreSQL form — then reformats the result. It’s free, instant, and nothing is stored.
How do I convert a PostgreSQL query to MySQL?
Set PostgreSQL as “From” and MySQL as “To”, then Translate. Double-quoted identifiers become backticks, ANSI functions map to their MySQL equivalents, and standard OFFSET … FETCH row limiting becomes LIMIT. Press the Swap (⇄) button to flip the direction instantly and translate back.
Can I convert SQL Server (T-SQL) to PostgreSQL or MySQL?
Yes. Choose SQL Server as “From” and PostgreSQL or MySQL as “To”. Query Studio converts bracketed [identifiers], turns TOP n into LIMIT n, maps ISNULL and GETDATE() to COALESCE and the target’s current-timestamp function, and rewrites OFFSET/FETCH paging to the target’s style. The same works in reverse to move from Postgres/MySQL to SQL Server.
Can Query Studio convert SQL to MongoDB?
Yes, and with no AI. Pick a SQL dialect as “From”, MongoDB as “To”, paste a SELECT and Translate. Query Studio turns it into a MongoDB find() query or an aggregation pipeline — WHERE becomes a filter, JOIN becomes $lookup, GROUP BY becomes $group, and ORDER BY/LIMIT become $sort/$limit — computed deterministically so you get the same result every time.
How do I convert LIMIT to TOP or FETCH FIRST?
Translate a query into SQL Server and LIMIT n becomes TOP n inside the SELECT; translate into IBM DB2 and it becomes FETCH FIRST n ROWS ONLY. Query Studio handles both directions automatically and rewrites any OFFSET into the correct pagination syntax for the target database.
Which databases and query languages are supported?
Query Studio supports 18 dialects. On the SQL side: MySQL, PostgreSQL, SQLite, MariaDB, SQL Server, IBM DB2, Snowflake, Amazon Redshift, Google BigQuery, DuckDB, Spark SQL, Hive, Trino and Presto. It also converts SQL to MongoDB, and formats and validates GraphQL, Elasticsearch and OpenSearch. Everything is free with no account.
Is Query Studio free, and do I need to sign up?
It’s completely free with no account and no usage limits. Translate, Explain, Visualize, Analyze, Optimize, Format, Validate and the ER Diagram tool all run for free — nothing is trial-limited or paywalled, and there’s nothing to install.
Are my queries stored or sent to a third party?
No. Your query is processed on the server only to return the result, then discarded — it is never saved, logged against you, or shared, and there is no sign-in. As good general practice, avoid pasting real credentials or secrets into any online tool.
Is Query Studio powered by AI?
No. Every result is computed deterministically by real SQL parsers and rule engines — so it’s instant, free, unlimited, and gives the same answer every time. Nothing is sent to an AI service, which also means no rate limits and no surprises in the output.
What is SQL’s logical execution order?
SQL is written SELECT-first, but a database executes it FROM-first: FROM and JOIN, then WHERE, then GROUP BY, HAVING, SELECT, window functions, ORDER BY, and finally LIMIT. The Explain and Visualize tabs walk your query through this real order — which is why, for example, you can’t use a SELECT alias inside WHERE.
What is the difference between WHERE and HAVING?
WHERE filters individual rows before grouping and cannot see aggregates; HAVING filters whole groups after GROUP BY and can test aggregates like COUNT(*) > 3. Run Explain on a grouped query to see exactly where each clause runs in the execution order.
How does the Performance Analyzer score my query?
It statically scans for well-known anti-patterns — SELECT *, UPDATE or DELETE without WHERE, cartesian joins, leading-wildcard LIKE, functions applied to filtered columns, unbounded ORDER BY and more — and subtracts points by severity to produce a 0–100 score and letter grade, with an explanation for every finding.
What does the Optimizer suggest, and what is a non-sargable query?
The Optimizer gives concrete rewrites — turning IN (SELECT …) into a JOIN or EXISTS, collapsing OR into IN, removing needless DISTINCT — plus CREATE INDEX candidates from your WHERE and JOIN columns. It also flags non-sargable predicates: filters the database can’t use an index for, usually because a column is wrapped in a function (WHERE YEAR(created_at) = 2024) or a LIKE pattern starts with a wildcard.
How do I generate an ER diagram from SQL?
Open the Diagram tab, paste one or more CREATE TABLE statements, and press Diagram. Query Studio parses your tables, primary keys and foreign keys and draws an entity-relationship diagram with connectors between related columns — no login and nothing to install.
Can I format and validate GraphQL or Elasticsearch queries?
Yes. Pick GraphQL, Elasticsearch DSL or OpenSearch as the dialect and use the Format or Validate tab. GraphQL is parsed and pretty-printed with the official GraphQL parser; Elasticsearch and OpenSearch request bodies are validated and beautified as JSON.
Can I chain the tools together?
Yes. After any result, a “Use this result →” bar sends the output straight into another tool — translate a query, then Explain, Analyze or Optimize the translated version in one click, with no copy-pasting.
More free tools
Git Rescue
Git cheat sheet & fix-it playbook
Table Grabber
Convert any table to CSV, Excel, Markdown, JSON, SQL and more
Storage Inspector
Chrome Web Store extension — see every byte a site stores