To share a reproducible example or try a query on a specific engine version, use DB Fiddle (MySQL, MariaDB, PostgreSQL, SQLite) or SQL Fiddle (which adds SQL Server and Oracle). For quick experiments where nothing should leave your machine, the DuckDB Wasm shell runs entirely in the browser. If your database is hosted on Supabase or Neon, use that platform's own SQL Editor. To give a team browser access to databases you run yourself, look at CloudBeaver Community, Adminer or, for MySQL and MariaDB only, phpMyAdmin.
"Online SQL editor" covers two different jobs. The first is a sandbox: you type a CREATE TABLE, a few INSERTs and a query, run it against a throwaway database, and perhaps share the link. That is how most people learn SQL, test an answer before posting it, or check how two engines differ. The second is a browser client for a real database: a cloud console such as the Supabase or Neon SQL Editor, or a web application such as CloudBeaver, phpMyAdmin or Adminer that you host next to your own server.
The two groups have different risks. Sandboxes are built for disposable data, and many of them run your SQL on someone else's server or keep it at a shareable URL, so never paste customer data, credentials or anything confidential into them. Web clients for real databases hold live connections, so where they run and who can reach them matters more than the editor features.
If you are practising, our SQL exercises give you a schema, sample data and an expected result that you can paste into any sandbox below, and the SQL functions library shows syntax differences between engines that a fiddle lets you check.
Quick picks
Pick an engine and version (MySQL, MariaDB, PostgreSQL or SQLite), write a schema and a query, and share the result as a link.
Lists SQL Server, Oracle and Oracle PL/SQL alongside PostgreSQL, MySQL, MariaDB and SQLite, with no install.
DuckDB documents that the shell runs entirely in the browser, with no server to send queries to.
Built into the Neon console, with saved queries, history, Explain and Analyze, and branch selection. Supabase users have the equivalent Supabase SQL Editor.
Apache 2.0 Community edition, deployed with Docker, giving a team browser access to many database types.
How we chose
We considered DB Fiddle, SQL Fiddle, OneCompiler, SQL Online IDE (sqliteonline.com), the DuckDB Wasm shell, the Supabase SQL Editor, the Neon SQL Editor, CloudBeaver, phpMyAdmin and Adminer. To be included, a tool had to be reachable and working in a browser on 7 October 2026 (or, for self-hosted clients, have a release or repository activity in the past year), run SQL rather than only format it, and state on an official page which database engines it supports.
For each tool we checked, from its own pages: which engines and versions it offers, whether queries run in your browser or on a server, how work is saved or shared, and any privacy statement the tool makes. Where a tool does not document how saved work is stored or who can see it, we say so rather than guess. None of this comes from our own use of the tools.
The order is not a ranking: the first five entries are sandboxes for learning and sharing, the last five are for working on a real database.
At a glance
| Tool | Price | Where SQL runs | Databases | Best for | Main trade-off |
|---|---|---|---|---|---|
| DB Fiddle | Free | DB Fiddle servers | MySQL, MariaDB, PostgreSQL, SQLite (several versions each) | Sharing a reproducible snippet | No SQL Server or Oracle; shared links are not private |
| SQL Fiddle | Free | SQL Fiddle servers | SQL Server, Oracle, PostgreSQL, MySQL, MariaDB, SQLite | Trying commercial engines without installing them | Disposable sample data only |
| OneCompiler | Free | OneCompiler servers | MySQL, PostgreSQL, SQL Server, SQLite, Oracle PL/SQL, MongoDB | Beginners wanting a simple run button | General code runner; little SQL-specific tooling |
| SQL Online IDE | Free (paid options listed) | Browser for SQLite, DuckDB, PGLite; servers for others | SQLite, DuckDB, PGLite, MariaDB, PostgreSQL, SQL Server | Local SQLite and DuckDB work in a tab | States it is not for personal data processing |
| DuckDB Wasm shell | Free | Your browser only | DuckDB (can query remote Parquet files) | Private, install-free analytics queries | DuckDB dialect only; browser memory limits |
| Supabase SQL Editor | Included with Supabase | Your Supabase Postgres | PostgreSQL (your Supabase project) | Working on a Supabase project | Only for Supabase databases |
| Neon SQL Editor | Included with Neon | Your Neon Postgres | PostgreSQL (your Neon project) | Working on a Neon project | Only for Neon databases |
| CloudBeaver | Freemium | Your server (Docker) | PostgreSQL, MySQL, MariaDB, ClickHouse and others | Team browser access to many engines | You install, secure and update it |
| phpMyAdmin | Free | Your server (PHP) | MySQL, MariaDB | MySQL and MariaDB on a web host | MySQL family only |
| Adminer | Free | Your server (single PHP file) | MySQL, MariaDB, PostgreSQL, SQLite, MS SQL, Oracle; more via plugins | A small multi-engine web client | Basic editor compared with desktop IDEs |
DB Fiddle
DB Fiddle describes itself as an online SQL database playground for testing, debugging and sharing SQL snippets. Its engine picker, checked on 7 October 2026, offers MySQL 9, 8.0, 5.7, 5.6 and 5.5; MariaDB 12, 11 and 10; PostgreSQL 9.4 through 18 plus 19 (Beta); and SQLite 3.30 through 3.46. You write a schema panel and a query panel, run them, and save the fiddle to get a link others can open and re-run.
The version choice is its main strength for learners and for anyone answering questions: you can check whether a function exists in PostgreSQL 13 or MySQL 5.7 before relying on it. It suits short, self-contained examples, such as one of our SQL exercises or a function from the functions library.
- No SQL Server or Oracle.
- Queries are sent to DB Fiddle's execution service rather than run in your browser, so treat anything you paste as shared.
- DB Fiddle does not document on its main page how long saved fiddles are kept or who can find them; assume anyone with the link can see one.
SQL Fiddle
SQL Fiddle lists seven SQL variants: SQL Server, SQLite, PostgreSQL, MySQL, MariaDB, Oracle and Oracle PL/SQL. It offers real-time execution and lets you share fiddles with others. The site is now run by ZZZ Projects, which states that the code for the current version is on GitHub; the earlier sqlfiddle3 code is published under the MIT licence.
It is the sandbox to reach for when the question involves T-SQL or Oracle syntax, which DB Fiddle does not cover. That makes it useful for checking T-SQL answers to our SQL interview questions or for comparing a query across engines.
- The home page does not state which engine versions are used.
- Shared fiddles are meant for public examples; do not paste real data.
- A sandbox only: you cannot connect it to your own database.
OneCompiler
OneCompiler is an online compiler for more than 110 languages that includes database editors: it publishes separate pages to write, run and share MySQL, PostgreSQL, SQL Server, SQLite, Oracle PL/SQL and MongoDB queries for free. The MySQL page, for example, comes with sample code and a short syntax reference covering DDL, DML, joins, views, triggers and stored procedures.
It suits someone who has never installed a database and wants the shortest path from a blank page to a result set, for example while working through an introductory lesson.
- The editor pages do not state database versions.
- It is a general code runner, so there is no schema browser, explain plan or result export of the kind database tools offer.
- The pages we checked do not explain whether shared code is public or how long it is kept.
SQL Online IDE
SQL Online IDE at sqliteonline.com supports SQLite, DuckDB, MariaDB (MySQL), PostgreSQL and MS SQL Server, plus PGLite, with Oracle listed as a test option. Its SQLite engine runs in the browser: the site moved from sql.js to the official SQLite WebAssembly build in April 2024. It keeps data in browser storage (localStorage, IndexedDB and OPFS), with optional auto-save of tabs and a query result history.
That in-browser SQLite and DuckDB support makes it practical for opening a small database file or CSV and querying it without installing anything. The site links to a pricing page for paid options.
- The site states that it is not intended for personal data processing and that the user assumes all risk for uploaded content.
- Only some engines run in the browser; MariaDB, PostgreSQL and SQL Server sessions use the site's servers.
- Work saved in browser storage can be lost if site data is cleared.
DuckDB Wasm shell
The DuckDB Web Shell is a DuckDB SQL shell running entirely in the browser via WebAssembly. DuckDB's documentation states that DuckDB-Wasm runs with no server to send queries to and no data leaving the user's machine, and that it can query remote Parquet files by reading only the bytes a query needs.
It is the strongest privacy option on this page for ad hoc work, and a quick way to try analytical SQL such as window functions and aggregations over a file. For how DuckDB compares with other engines, see DuckDB vs SQLite and DuckDB vs PostgreSQL.
- DuckDB documents that the Wasm build is single-threaded by default and capped at 4 GB of memory, and browsers may impose stricter limits.
- DuckDB's SQL dialect is close to PostgreSQL but not identical to MySQL, SQL Server or Oracle.
- DuckDB does not document a way to share a shell session as a link, so it is less suited to posting examples than a fiddle.
Supabase SQL Editor
Every Supabase project is a full Postgres database, and the Dashboard's SQL Editor is where Supabase's documentation sends you for ad hoc queries and saved snippets. Supabase lists syntax highlighting, auto-completion, error detection, execution history and an AI assistant that turns natural-language requests into SQL. The editor is part of Supabase Studio, which is in the Apache 2.0 licensed Supabase repository, and Supabase says it is available in self-hosted deployments, with some collaboration features such as shared snippets limited there.
Use it when the database already lives on Supabase; it is not a general-purpose client. For the wider platform, see Supabase alternatives and Supabase vs Neon.
- Connects only to Supabase databases.
- Queries run against a real database, so a mistaken UPDATE or DELETE changes real data; use a branch or a copy for experiments.
- Free Supabase projects are paused after one week of inactivity, according to the pricing page.
Neon SQL Editor
The Neon SQL Editor runs in the Neon Console. Neon documents saved queries, a per-project query history, Explain (EXPLAIN) and Analyze (EXPLAIN ANALYZE) buttons, AI features that generate SQL from natural language and offer a "Fix with AI" option, and a selector to choose the branch and database before running a query.
Branch selection is the useful part for real work: you can try a migration on a branch copied from production before running it on the main branch. Neon is now part of Databricks. See Supabase vs Neon and Neon vs PlanetScale.
- Connects only to Neon databases.
- Neon documents that queries saved to History are limited to 9 KB and longer ones are truncated.
- AI requests are limited to 5 every 60 seconds.
CloudBeaver
CloudBeaver is the web version of DBeaver: a web server that provides a browser interface to databases. The Community edition is licensed under Apache 2.0 and deployed with Docker; version 26.2.2 was released on 5 October 2026. Its repository lists PostgreSQL, MySQL, MariaDB, ClickHouse, Firebird and other databases. DBeaver also sells a commercial CloudBeaver edition, listed on its edition comparison page.
It suits teams that want one shared, browser-based client instead of installing a desktop tool on every machine. For the desktop product, see our DBeaver review.
- You install, secure, patch and back up the server yourself; release notes for 26.2.2 include several security fixes, so updating matters.
- Some features are in the paid edition only.
- Exposing it to the internet without additional access controls puts every connected database at risk.
phpMyAdmin
phpMyAdmin is a free tool written in PHP for administering MySQL and MariaDB over the web, released under the GNU GPL version 2. Besides a SQL query box it covers tables, indexes, users and import and export. The latest release listed on its site on 7 October 2026 was 5.2.3, from October 2025.
It is often already installed on shared hosting and in local stacks such as XAMPP, which makes it the browser SQL editor many people meet first. See best MySQL GUI tools for desktop alternatives.
- Works with MySQL and MariaDB only.
- A public phpMyAdmin install is a common attack target; restrict access by IP or with web server authentication.
- The SQL editor is basic compared with desktop IDEs.
Adminer
Adminer is a database management tool in a single PHP file. Its site lists MySQL, MariaDB, PostgreSQL, SQLite, MS SQL and Oracle, with plugins for Elasticsearch, MongoDB, Redis, ClickHouse, Firebird and others. It is free for commercial and non-commercial use under the Apache License or GPL 2, and version 6.1.1 was released on 25 September 2026.
It covers more engines than phpMyAdmin with less to install, which suits developers who need occasional browser access to a PostgreSQL or MySQL server. Adminer does not allow connections to databases without a password and rate-limits login attempts, and recommends extra protection such as IP restrictions.
- A single-page interface with fewer conveniences (autocomplete, tabs, explain plan views) than desktop clients.
- Non-core databases depend on plugins.
- As with any self-hosted web client, you are responsible for keeping it off the open internet or behind authentication.
How to choose
Learning or sharing a snippet: start with DB Fiddle or SQL Fiddle, picking whichever supports the engine you are studying. Use invented data only. If you want to keep everything on your own machine, use the DuckDB Wasm shell or the in-browser SQLite engine in SQL Online IDE. When you are ready for structured practice, work through our SQL exercises.
Working on a real database: use the console of the platform that hosts it (Supabase or Neon) or a web client you host yourself (CloudBeaver, Adminer, phpMyAdmin). For daily development work, a desktop client usually offers more than any browser editor; see best SQL IDEs and best free database management tools.
Frequently asked questions
Can I practise SQL online without installing anything?
Yes. DB Fiddle, SQL Fiddle, OneCompiler, SQL Online IDE and the DuckDB Wasm shell all run SQL from a browser tab. Our SQL exercises include the schema and sample data to paste in.
Which online SQL editor supports SQL Server?
SQL Fiddle lists SQL Server, and OneCompiler and SQL Online IDE also offer SQL Server editors. DB Fiddle does not.
Is it safe to paste my data into an online SQL editor?
Not for real or personal data. Most sandboxes run queries on their own servers and share work by link, and SQL Online IDE states it is not intended for personal data processing. The DuckDB Wasm shell is the exception among the tools here: DuckDB documents that data does not leave your machine.
Can I connect an online SQL editor to my own database?
Sandboxes cannot. Use your hosting platform's console (for example the Supabase or Neon SQL Editor) or a web client you host yourself, such as CloudBeaver, Adminer or phpMyAdmin.
Do online SQL fiddles save my work?
DB Fiddle and SQL Fiddle save a fiddle when you share it as a link. SQL Online IDE keeps work in your browser's storage. DuckDB does not document a share-by-link feature for its shell. Check each tool before relying on it to keep anything.
Sources
- DB Fiddle
- SQL Fiddle
- SQL Fiddle 3 repository (licence)
- OneCompiler MySQL editor
- SQL Online IDE
- DuckDB-Wasm documentation
- Supabase SQL Editor
- Supabase database documentation
- Neon SQL Editor documentation
- CloudBeaver GitHub repository
- phpMyAdmin
- Adminer
Checked October 2026.
How we research these guides: our editorial method.