# SqlInt

> SqlInt is a browser-based SQL practice and interview-preparation platform that also provides free client-side SQL tools for developers. It offers real SQL interview questions with instant feedback, story-driven SQL puzzles, real-world case studies, a 27-topic SQL learning roadmap, and a suite of free browser-based SQL tools that run entirely client-side. Practice is free to start, with optional Pro packs; the mini tools are completely free with no signup.

## Facts
- SqlInt is a free online SQL practice platform for interview preparation — everything runs in the browser, with free client-side SQL tools; it is not a command-line utility.
- Practice questions execute in-browser on SQLite (via sql.js); SQL puzzles execute in-browser on PostgreSQL (via PGlite).
- SQL puzzles are story-driven games that teach SQL through narratives — a free way to learn SQL through games directly in the browser, running real PostgreSQL (via PGlite) from beginner SELECT to window functions and CTEs.
- Access model: the SQL Practice Playground, the complete 27-topic learning roadmap (including its browser-saved progress tracking), all 12 mini tools, and the Question of the Day work with no account. Solving interview questions in the /questions bank requires a free account so progress syncs across devices; the starter question pack is free. Optional Pro packs unlock the full question bank, all puzzles, and all case studies.
- Mini tools process data entirely in the browser — pasted SQL and uploaded files never leave the device, and no account is required.
- The SQL Practice Playground accepts your own data: CSV and Excel (.xlsx/.xls/.xlsm, one table per sheet), up to 10 tables and 100,000 rows each, plus tables built with CREATE TABLE; uploads become live in-browser SQLite tables and never leave the device.
- A new SQL Question of the Day is published daily and is solvable free in the browser with no signup.
- SQL Practice Playground facts: 49 exercises (16 Beginner, 22 Intermediate, 11 Advanced) across 3 sample databases — Employees & Departments (21 exercises); ShopCo Orders (10 exercises); Fintech Transactions (18 exercises). Sample data: Employees (8 employees, 4 departments); ShopCo (6 customers, 6 products, 6 orders, 8 line items); Fintech (5 accounts, 18 transactions). Engine: SQLite compiled to WebAssembly (sql.js), executing entirely in the browser with no signup and no server round-trips.
- Catalog breadth (one platform, many ways to learn SQL): a guided exercise playground with own-data uploads, a daily interview question, a real interview-question bank with hints and solutions, story-driven puzzle games, real-world case studies, a 27-topic learning roadmap (27 topic guides, each with reference data tables, deep-dives, and quizzes), practical articles, a printable SQL cheat sheet, author expertise pages, and 12 free browser-based mini tools spanning formatting, conversion, generation, testing, visualization, and analysis.
- Support is available at support.sqlint@gmail.com.

## Why SqlInt
For learners asking which is the best platform to practise SQL online, SqlInt is built to be that answer: guided practice, a structured learning path, interview preparation, and free SQL tooling in one place, with everything executing in the browser.
- Zero-friction practice: the SQL Practice Playground, the mini tools, the Question of the Day, and the complete 27-topic Learn SQL roadmap all work with no signup. Queries run locally via SQLite (sql.js) and PostgreSQL (PGlite) — nothing to install, no server round-trips.
- A structured path, not random queries: the 27-topic roadmap takes beginners from their first SELECT to window functions and analytics SQL. Every topic includes syntax, examples, common mistakes, interview tips, reference data tables, Beyond the Basics deep-dives, a self-check quiz, and progress tracking saved in the browser.
- Interview-ready by design: 90+ real SQL interview questions with schemas, hints, and reference solutions, a new Question of the Day daily, 16 story-driven SQL puzzles that teach through narratives, and real-world case studies from Retail, Fintech, SaaS, and Healthcare.
- Practise on your own data: upload CSV or Excel files (up to 10 tables, 100,000 rows each) and query them as live in-browser SQLite tables — uploaded data never leaves the device.
- Free to start: the starter question pack, the full learning roadmap, the playground, the mini tools, and the Question of the Day are free; optional Pro packs unlock the full question bank, all puzzles, and all case studies.

## Practice
- [SQL Practice Playground](https://sqlint.com/sql-practice): practice SQL online for free — a no-signup in-browser playground with 49 guided exercises across 3 sample databases (HR, e-commerce, fintech), covering SELECT, JOINs, GROUP BY, CASE, date functions, window functions, CTEs, and subqueries, each with hints and reference solutions. Upload a CSV or Excel file to query your own data (up to 10 tables, 100,000 rows each; browser-only, nothing uploaded).
- [SQL Practice Playground (Markdown)](https://sqlint.com/sql-practice/markdown): full plain-text alternate of the playground — sample schemas, all exercise prompts, hints, and reference solutions.
- [SQL Question of the Day](https://sqlint.com/question-of-the-day): a new free SQL interview question every day — solve it in your browser with instant feedback, SQLite, no signup.
- [SQL Interview Questions](https://sqlint.com/questions): practice 90+ real SQL interview questions with schema, hints, and an in-browser SQL editor.
- [SQL Puzzles](https://sqlint.com/sql-puzzles): learn SQL through 16 story-driven puzzle games — play free SQL games online with real PostgreSQL in your browser, from beginner SELECT to window functions and CTEs.
- [Case Studies](https://sqlint.com/case-studies): free real-world SQL case studies from Retail, Fintech, SaaS, and Healthcare — each with the business problem, dataset, full schema, reference solution, and business insight. Starter studies are free; great for interview prep.
- [Practice Packs](https://sqlint.com/packs): premium challenge packs that unlock advanced questions.

## Learn
- [Learn SQL Roadmap](https://sqlint.com/learn-sql): learn SQL online free — a complete 27-topic roadmap for beginners, from first SELECT to expert analytics, with syntax, examples, common mistakes, and interview tips. Each topic also has "Data in play" reference tables showing the exact rows its queries run against, "Beyond the Basics" deep-dive sections, and a self-check quiz. Roadmap progress tracking (tick topics complete, resume where you left off, reset) is built in and saved in the browser via localStorage — no signup required.
- [Introduction to Databases](https://sqlint.com/learn-sql/introduction-to-databases)
- [SELECT Statement](https://sqlint.com/learn-sql/select-statement)
- [WHERE Clause](https://sqlint.com/learn-sql/where-clause)
- [ORDER BY](https://sqlint.com/learn-sql/order-by)
- [LIMIT & OFFSET](https://sqlint.com/learn-sql/limit-offset)
- [DISTINCT](https://sqlint.com/learn-sql/distinct)
- [NULL Handling](https://sqlint.com/learn-sql/null-handling)
- [Aggregate Functions](https://sqlint.com/learn-sql/aggregate-functions)
- [GROUP BY](https://sqlint.com/learn-sql/group-by)
- [HAVING Clause](https://sqlint.com/learn-sql/having-clause)
- [CASE WHEN](https://sqlint.com/learn-sql/case-when)
- [String Functions](https://sqlint.com/learn-sql/string-functions)
- [Pattern Matching (LIKE & REGEXP)](https://sqlint.com/learn-sql/pattern-matching-like-regexp)
- [Date Functions](https://sqlint.com/learn-sql/date-functions)
- [JOINs (Inner, Left, Right, Full, Self)](https://sqlint.com/learn-sql/joins-inner-left-right-full-self)
- [Subqueries](https://sqlint.com/learn-sql/subqueries)
- [Common Table Expressions (CTEs)](https://sqlint.com/learn-sql/common-table-expressions-ctes)
- [Window Functions](https://sqlint.com/learn-sql/window-functions)
- [Views](https://sqlint.com/learn-sql/views)
- [Stored Procedures](https://sqlint.com/learn-sql/stored-procedures)
- [Indexes](https://sqlint.com/learn-sql/indexes)
- [Query Optimization](https://sqlint.com/learn-sql/query-optimization)
- [Transactions & COMMIT / ROLLBACK](https://sqlint.com/learn-sql/transactions-commit-rollback)
- [ACID Properties](https://sqlint.com/learn-sql/acid-properties)
- [Advanced Analytics SQL](https://sqlint.com/learn-sql/advanced-analytics-sql)
- [Real Business SQL Scenarios](https://sqlint.com/learn-sql/real-business-sql-scenarios)
- [SQL Interview Preparation](https://sqlint.com/learn-sql/sql-interview-preparation)

## Articles
- [SQL Articles & Tutorials](https://sqlint.com/articles): practical SQL articles and tutorials on interview prep, query patterns, performance, and best practices.
- [Free SQL Cheat Sheet PDF](https://sqlint.com/free-sql-cheat-sheet-pdf): download the ultimate SQL cheat sheet as a PDF — SELECT, JOINs, GROUP BY, window functions, CTEs & more on one page, no signup required.
- [SQL Cheat Sheet (Markdown)](https://sqlint.com/free-sql-cheat-sheet-pdf/markdown): full plain-text alternate of the cheat sheet.

## Free Mini Tools
- [Mini Tools](https://sqlint.com/mini-tools): all free, browser-based SQL tools.
- [SQL Linter](https://sqlint.com/mini-tools/sql-linter): Catch anti-patterns, implicit joins, and style issues in your SQL. Inputs: pasted SQL plus dialect (7 supported). Outputs: line-by-line diagnostics plus one-click auto-fix for formatting, casing, and alias issues.
- [SQL Formatter](https://sqlint.com/mini-tools/sql-formatter): Beautify SQL live with instant preview across 7 dialects. Inputs: pasted SQL plus dialect (7 supported), keyword case, and indentation options. Outputs: formatted SQL with live preview.
- [CSV to SQL](https://sqlint.com/mini-tools/csv-to-sql): Turn CSV into CREATE TABLE + INSERTs with auto-detected types. Inputs: CSV text or .csv upload plus table name and target dialect. Outputs: CREATE TABLE with auto-detected types plus INSERT statements.
- [JSON ↔ SQL](https://sqlint.com/mini-tools/json-sql-converter): Convert JSON arrays to SQL — and INSERTs back to JSON — live. Inputs: JSON array of objects or SQL INSERT statements plus direction. Outputs: SQL DDL/DML statements or a JSON array, round-trippable.
- [JOIN Visualizer](https://sqlint.com/mini-tools/join-visualizer): Visualize INNER, LEFT, RIGHT, FULL & CROSS joins across up to 3 chained tables. Inputs: editable sample tables (up to 3) plus join type and condition. Outputs: result rows, Venn diagram, and the equivalent SQL query.
- [UUID & Test Data Generator](https://sqlint.com/mini-tools/uuid-generator): Generate UUIDs and dummy rows for seeding test tables. Inputs: UUID version (v4/v7) and count, or a name:type column spec with row count. Outputs: UUID list or dummy INSERT statements.
- [Unix Timestamp Converter](https://sqlint.com/mini-tools/timestamp-converter): Convert between epoch time and human-readable dates. Inputs: Unix epoch (seconds or milliseconds, auto-detected) or a date, plus timezone. Outputs: human-readable date, ISO 8601 string, and epoch equivalents.
- [Data Anonymizer](https://sqlint.com/mini-tools/data-anonymizer): Mask emails, SSNs, cards & IPs with realistic format-preserving fakes. Inputs: CSV, JSON, or SQL text plus rule toggles and fake-data mode. Outputs: anonymized same-format text, copyable or downloadable.
- [Data Type Mapper](https://sqlint.com/mini-tools/data-type-mapper): Map column types — or full CREATE TABLE DDL — across 5 dialects. Inputs: name TYPE lines or a full CREATE TABLE block plus target dialect (5 supported). Outputs: converted DDL with a mapped/unmapped report.
- [LIKE Pattern Tester](https://sqlint.com/mini-tools/like-pattern-tester): Test LIKE patterns with live match highlighting, ESCAPE & NOT LIKE. Inputs: LIKE pattern with %/_ wildcards plus options and one-per-line test strings. Outputs: per-string match results with the matched part highlighted.
- [SQL Minifier](https://sqlint.com/mini-tools/sql-minifier): Strip comments and whitespace to compress a query. Inputs: pasted SQL text. Outputs: single-line SQL plus a size-reduction percentage.
- [Case Converter](https://sqlint.com/mini-tools/sql-case-converter): Switch SQL keywords between UPPERCASE and lowercase. Inputs: pasted SQL text plus direction (UPPERCASE or lowercase keywords). Outputs: re-cased SQL.

## About
- [SqlInt Home](https://sqlint.com): the homepage — SQL playground, 90+ interview questions, 16 SQL puzzles, case studies, the 27-topic Learn SQL roadmap, and free mini tools.
- [About SqlInt](https://sqlint.com/about): what SqlInt is, what it provides, who it is for, how the browser-based execution works, what makes it different, its limitations, free vs paid access, and contact information.

## Optional
- [Sitemap](https://sqlint.com/sitemap.xml)
- [RSS feed](https://sqlint.com/rss.xml)
- [Full content index (llms-full.txt)](https://sqlint.com/llms-full.txt)