JSON Schema to SQL DDL Converter

Transform JSON Schema models and constraints into multi-dialect relational SQL CREATE TABLE migrations.

At a glance

JSON Schema to SQL DDL Converter is a free developer utility that transforms JSON Schema Draft-04 through 2020-12 specifications into production SQL CREATE TABLE statements for PostgreSQL, MySQL, and SQLite. It automatically detects primary keys, formats (date-time, uuid), nullability, and foreign keys 100% client-side in browser memory.

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100% Client-Side JSON Schema to SQL DDL Converter

Zero Server Uploads

Transform JSON Schema definitions into production SQL CREATE TABLE statements across PostgreSQL, MySQL, and SQLite with automatic primary keys, nullability, formats, constraints, and foreign keys.

Local Browser Sandbox
Presets:
0 lines · 0 chars
0 tables · 0 columns
0 Tables 0 Columns 0 Foreign Keys
Client-Side Evaluated

Why Use This JSON Schema to SQL DDL Converter?

100% Client-Side Privacy: Your JSON schemas and database structures never leave your device.
Tri-Dialect Generation: Instant toggle between PostgreSQL, MySQL, and SQLite syntax.
Inverse Nullability: Accurately maps JSON Schema required arrays to SQL NOT NULL constraints.
Smart Reference & FK Resolution: Resolves $defs and definitions pointers into separate tables and FOREIGN KEY constraints.

How to Use JSON Schema to SQL DDL Converter

1

Input JSON Schema

Paste your JSON Schema definition or load one of the pre-configured database presets.

2

Select Dialect & Options

Choose between PostgreSQL, MySQL, or SQLite and configure table naming and foreign keys.

3

Copy or Export SQL

Copy the generated DDL statements or download them directly as a .sql file.

JSON Schema to PostgreSQL DDL example

Converts a User JSON Schema into a PostgreSQL CREATE TABLE statement with an auto-incrementing serial primary key and NOT NULL name.

JSON Schema Source 
{
  "title": "User",
  "type": "object",
  "properties": {
    "id": { "type": "integer" },
    "name": { "type": "string" },
    "bio": { "type": "string" }
  },
  "required": ["id", "name"]
}
PostgreSQL DDL Processed 
CREATE TABLE "users" (
  "id" SERIAL PRIMARY KEY,
  "name" VARCHAR(255) NOT NULL,
  "bio" VARCHAR(255) NULL
);

Technical Specifications & Engine Details

Technical specifications and engine details for JSON Schema to SQL DDL Converter
Specification Details
Supported JSON Schema Formats Draft-04, Draft-07, Draft 2019-09, Draft 2020-12, OpenAPI 3.0/3.1
Supported SQL Dialects PostgreSQL, MySQL / MariaDB, SQLite
Execution Mode 100% Client-Side In-Browser (Zero server latency)
Nullability Mapping Properties in required array → NOT NULL, omitted → NULL
Generated Output SQL DDL (CREATE TABLE, PRIMARY KEY, FOREIGN KEY, CHECK, ENUM, DEFAULT)
Maintained by Pragyan Pahadi

100% Client-Side Privacy Guarantee

Your files remain strictly on your local device. Zero data is transmitted to external servers.

Frequently Asked Questions

How does JSON Schema nullability map to SQL DDL?
Properties listed in the parent required array receive NOT NULL constraints. Properties omitted from required default to NULL. If a property defines type as an array containing null (e.g. ["string", "null"]), it also defaults to NULL.
How are primary keys detected and generated?
Fields named id, or flagged with primaryKey: true, are automatically synthesized as dialect-specific primary keys (e.g. SERIAL PRIMARY KEY in PostgreSQL, INT AUTO_INCREMENT PRIMARY KEY in MySQL, or INTEGER PRIMARY KEY AUTOINCREMENT in SQLite). String fields with format: uuid become UUID/CHAR(36) primary keys.
How does the tool handle definitions and $defs?
Each object schema declared inside definitions or $defs is generated as an independent CREATE TABLE statement. References via $ref automatically generate FOREIGN KEY constraints when foreign key synthesis is enabled.
Is any schema data uploaded to a server?
No. The parser and SQL generator operate 100% in-browser within your local JavaScript sandbox. Zero network requests or telemetry are sent.

Methodology

This tool runs entirely in your browser. The example above shows a representative input and the result it produces.

Last updated .

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