"@context": "https://schema.org",
"@type": "Article",
"headline": "Your Content",
"author": {
  "@type": "Person",
  "name": "Jane Smith"
},
"datePublished": "2025-03-20",
"publisher": {
  "@type": "Organization",
  "name": "Schema.biz"
}

Free & open-source developer tools

The Complete Schema Toolkit

Free tools for structured data markup, database design, and API validation. No signup required — everything runs in your browser.

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Everything You Need

Three categories of tools covering the full schema lifecycle.

Markup Tools

Generate and validate structured data markup for SEO. JSON-LD, Microdata, and Schema.org made easy.

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Database Tools

Design schemas, generate SQL, and build ERDs. Visual tools for database architecture.

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API Tools

Build and validate OpenAPI specs, JSON Schema, and API contracts. Design APIs visually.

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Featured Tools

The most popular tools to get you started.

Markup

JSON-LD Generator

Create structured data markup with a visual editor. Supports all Schema.org types.

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Markup

AI Search Optimizer

Optimize your schema markup for ChatGPT Search, Perplexity, and Google AI Overviews.

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Database

Schema Designer

Design database schemas visually with drag-and-drop. Export SQL for any dialect.

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Database

SQL to Diagram

Paste CREATE TABLE statements and instantly generate an interactive ER diagram.

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API

Mock Data Generator

Generate realistic test data from any JSON Schema. Locale-aware, seeded output.

Open tool

API

Breaking Change Detector

Compare API schema versions and detect breaking, warning, and safe changes.

Open tool

Why Schema.biz?

Built with developer trust in mind.

100% Browser-Based

Every tool runs entirely in your browser. Your data never leaves your machine.

Free Forever

All tools are completely free. No premium tiers, no feature gates, no limits.

No Account Required

Start using any tool immediately. No signup, no email, no friction.

Developer-First

Built by developers, for developers. Clean output you can copy straight into your project.

Related Resources

Guide

Beginner's Guide to Schema Markup

Learn what structured data is, why it matters for SEO, and how to implement it step by step.

Guide

Database Design Fundamentals

Normalization, relationships, naming conventions, and patterns for relational databases.

All Processing Happens in Your Browser

Schema.biz tools use client-side JavaScript exclusively. Your schemas, database designs, and API specs never touch our servers. What you build stays on your machine.