Free Online SQL Formatter — 15+ Dialects, Client-Side, No Upload
Most online SQL formatters send your queries to their server. That's a problem when you're working with production schemas, business logic, or queries that might contain sensitive patterns.
sqlformat.io runs entirely in your browser. Zero bytes leave your device. You can disconnect your internet after the page loads and keep formatting offline.
| Tool | What It Does |
|---|---|
| SQL Formatter | Format/beautify SQL across 15+ dialects (MySQL, PostgreSQL, SQLite, BigQuery, Snowflake, T-SQL…) |
| Diff | Compare two SQL queries side-by-side, highlighted differences |
| Minify | Compress SQL — strip whitespace and comments for embedding |
| Validate | Syntax-check SQL across dialects |
| ER Diagram | Visualize table relationships as diagrams |
| SQL to JSON | Convert SQL query results or schemas to JSON |
| Data Generator | Generate realistic test data for any schema |
| Explain Visualizer | Turn MySQL EXPLAIN / PostgreSQL EXPLAIN ANALYZE output into a readable tree |
| Dialect Converter | Convert SQL between dialects (MySQL ↔ PostgreSQL, etc.) |
| Regex Replace | Search and replace with regex across SQL files |
| Escape/Unescape | Handle string escaping for SQL, JSON, HTML |
# No install needed — just open in any browser
open https://sqlformat.io
# Or clone and run locally
git clone https://github.com/sharefun2023/sqlformat.io.git
cd sqlformat.io
python3 -m http.server 8080 --directory public
# → http://localhost:8080User pastes SQL
↓
Web Worker (off main thread)
↓
sql-formatter library with dialect config
↓
Formatted SQL → rendered with syntax highlighting
All formatting happens inside a Web Worker so the UI stays responsive even on 1000+ line queries.
- Vanilla JavaScript — no framework, no build step
- sql-formatter — formatting engine (50KB gzipped)
- Web Workers — non-blocking background processing
- Cloudflare Pages — global edge hosting, free tier
| Server-Side Formatters | sqlformat.io | |
|---|---|---|
| Privacy | Queries sent to server ❌ | Zero bytes leave browser ✅ |
| Offline | Needs internet ❌ | Works after page load ✅ |
| Speed | Round-trip latency ❌ | Instant ✅ |
| Limits | Rate-limited, API keys ❌ | Unlimited, no signup ✅ |
| Cost | Paid tiers, quotas ❌ | Free forever ✅ |
MIT — LICENSE
- Live site: sqlformat.io
- More free tools: 23232322.xyz | imgloft.com | pagetext.io