The share link contains your schema — share it only where you'd share the schema itself.
About the GraphQL SDL validator
The GraphQL Schema Definition Language (SDL) is the text format used to describe a GraphQL API's type system — its object types, interfaces, unions, enums, input types and scalars, along with the fields, arguments and directives that connect them. This tool validates an SDL document: it confirms the schema is both syntactically correct and semantically coherent.
Validation happens in two stages. First the document is parsed, which catches syntax problems like a malformed field or an unterminated type. Then schema-level semantic checks run: a Query root type must exist, every referenced type must be defined, non-null and list wrappers must be used consistently, and a type that declares it implements an interface must actually supply all of that interface's fields. Directives are checked against their definitions and allowed locations. When the parser can pinpoint a problem, the error is reported with a line number you can click to jump to.
Note that this validates the schema, not queries. It does not check operations — queries, mutations or subscriptions — sent against the schema. Everything runs locally in your browser; your schema is never uploaded.
GraphQL validation FAQ
What SDL features are validated?
The validator parses the full Schema Definition Language: object, interface, union, enum, input and scalar types, fields and arguments, non-null and list wrappers, directives, and the Query, Mutation and Subscription root types. It then runs schema-level semantic checks, such as confirming that a type which claims to implement an interface actually provides all of that interface's fields.
Does it validate queries or operations?
No — SDL only. This page validates the schema definition, not query, mutation or subscription operations executed against it. Operation validation requires a schema plus a document and is outside the scope of this tool.
Why does my schema parse but still fail?
Parsing only checks syntax. After parsing, the validator runs semantic schema checks. A schema can be syntactically perfect yet still be invalid — for example, referencing a type that isn't defined, declaring no Query root type, or implementing an interface without supplying all its fields. Those surface as semantic errors even though the document parsed cleanly.
Are directives checked?
Yes. Directive usage is validated against built-in directive definitions and any directives you declare in the schema, including whether a directive is applied in a location it allows.
Should I use GraphQL SDL or OpenAPI?
GraphQL SDL defines a single typed graph queried from one endpoint; OpenAPI describes a REST/HTTP API of paths and methods. For a full comparison of when to choose each, see the guide OpenAPI vs GraphQL at /guides/openapi-vs-graphql/.