About schemavalidator.dev

schemavalidator.dev validates JSON Schema, OpenAPI/Swagger, GraphQL SDL, YAML, Avro, Protobuf, XML/XSD, JSON-LD, and TOML — each with its own dedicated validator page. All from one consistent interface, with no account to create and nothing to install. Paste your schema, get line-precise feedback, and move on.

Your schema stays yours

Validation runs entirely in your browser. The schema you paste is parsed and checked on your own device — there is no upload step and no copy is kept anywhere. That means you can validate internal API contracts, config files and anything else sensitive with zero exposure: it simply never leaves your machine, so there is nothing to leak.

What we never touch: your schema. It is processed locally and is never transmitted to a server. What we collect: anonymous, cookieless page counts — which pages are visited and roughly how often — so we can see which formats people use and keep improving the tool. That usage data never includes your schema content or anything that identifies you personally.

The fragmentation problem

Validating schemas today usually means juggling a different single-purpose website for every format — one for JSON Schema, another for OpenAPI, another for GraphQL, another for YAML — each with its own layout, quirks and trust level. schemavalidator.dev exists to collapse that into a single, consistent tool. The same editor, the same error display and the same privacy guarantees apply no matter which format you are working in, so you can switch between them without relearning a new interface or re-evaluating who you are pasting your data into.

How it works

Under the hood we lean on well-established, open-source libraries rather than reinventing parsers. JSON Schema documents are validated with ajv, checked against the appropriate draft meta-schema; OpenAPI definitions are validated against the OpenAPI meta-schema using the same ajv foundation. GraphQL SDL is parsed and validated with the reference graphql-js implementation, YAML is parsed with js-yaml, Avro schemas with avsc, Protobuf definitions with protobufjs, JSON-LD documents with jsonld, and TOML configs with smol-toml. XML/XSD well-formedness uses the browser-native DOMParser — no additional dependency needed. These run in the browser, so the validation logic you rely on is the same battle-tested code used across the ecosystem.

What's next

Coming next: validating data against a schema (e.g. JSON against a JSON Schema, XML against an XSD) and a /guides content hub.

Contact

Questions, bug reports or feature requests? Email info@schemavalidator.dev. There is no contact form by design — a form would need a backend, which would break the client-side-only, nothing-leaves-your-browser promise.