JSON to Avro Schema - Generate Apache Avro Schema from JSON

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What Is a JSON to Avro Schema Converter?

Apache Avro is a compact binary serialization format widely used in data pipelines, Kafka, and Hadoop ecosystems. An Avro schema (stored as .avsc) defines the structure of your data as a JSON document with typed fields. This tool reads any JSON object and generates a valid Avro record schema with correct field types, nullable unions, and nested record definitions.

How to Use

Paste your JSON object into the left textarea.
Set a root record name (default: Root) and namespace.
The Avro schema is generated automatically as you type.
Click Copy and save the output as a .avsc file.

Features

Generates valid Avro record schemas with correct scalar types: string, long, double, boolean.
All fields use nullable unions (e.g. ["null", "string"]) with default: null.
Nested objects become inline nested record definitions.
Arrays are converted to Avro array type with inferred item type.
Configurable root record name and namespace.
Runs entirely in your browser — no data is sent to any server.

FAQ

Why are fields wrapped in a union with null?

Avro fields are not nullable by default. To allow a field to be absent or null, the type must be a union like ["null", "string"]. This tool generates nullable unions for all fields as a safe default, since JSON values can always be null.

How are JSON numbers mapped to Avro types?

Integers map to long (64-bit) and floating-point numbers map to double. You can manually change these to int or float after generation if needed.

What is the namespace field for?

The namespace acts like a Java package name and helps avoid naming conflicts when multiple schemas are used together. It is optional — leave it blank to omit it from the generated schema.