Free ExtendsClass JSON Schema Validator Alternative
ExtendsClass offers an online JSON Schema validator that uses the Ajv library to validate JSON documents against schemas. It supports JSON Schema draft-07 and provides both validation and schema generation features in a straightforward web interface. The tool is free to use and requires no signup. However, like many online validators, it sends your JSON to their servers for validation. Fixie's JSON Schema Validator performs all validation client-side in your browser, ensuring your data never leaves your machine.
Try JSON Schema Validator Free →JSON Schema Validator vs ExtendsClass JSON Schema Validator
| Feature | Fixie JSON Schema Validator | ExtendsClass JSON Schema Validator |
|---|---|---|
| Price | Free forever | Free |
| Signup Required | No | No |
| Privacy / Data Handling | 100% client-side validation | Server-side validation |
| Supported Drafts | Draft 4, 6, 7, 2019-09, 2020-12 | Draft 7 |
| Ads | None | May display ads |
| Error Highlighting | Yes (inline with line numbers) | Yes (errors shown below editors) |
| Schema Generation | Not currently available | Yes (generate schema from JSON sample) |
Why Choose Fixie?
ExtendsClass provides a practical JSON Schema validator with a clean interface and automatic validation as you type. The tool uses the widely-respected Ajv library for validation, ensuring accurate results according to the JSON Schema specification. One particularly useful feature is the ability to generate a JSON schema from a sample JSON document, which can speed up schema creation.
The main privacy consideration is that your JSON and schema are sent to ExtendsClass's servers for validation. For most use cases this is fine, but if you're working with sensitive data, proprietary API responses, or confidential configuration files, server-side validation means your data passes through third-party infrastructure.
Fixie's JSON Schema Validator performs all validation entirely in your browser using JavaScript. Your JSON and schema never leave your machine, making it suitable for sensitive data. We support a broader range of JSON Schema drafts (4, 6, 7, 2019-09, and 2020-12) compared to ExtendsClass's focus on draft-07. While we don't currently offer schema generation from samples, our validation capabilities are comprehensive and privacy-preserving. Choose ExtendsClass if you need the schema generation feature; choose Fixie if data privacy is a priority.
How to Use JSON Schema Validator
Step 1: Open the Validator
Go to fixie.tools/json-schema — no account needed.
Step 2: Paste Your JSON
Copy your JSON document into the left editor panel. Syntax highlighting will help you spot any formatting issues.
Step 3: Add Your Schema
Paste your JSON Schema into the right editor panel. Select the appropriate draft version from the dropdown.
Step 4: Validate
Click Validate to check if your JSON conforms to the schema. Any errors will be highlighted with line numbers and descriptions.