API Design
GraphQL Schema Validator
Paste a GraphQL schema in SDL format to validate syntax, non-null rules, input type constraints, circular type detection, and required root types.
Calculations run locally in your browserTool
About this tool
GraphQL Schema Validator
The GraphQL Schema Validator checks SDL schema syntax, non-null field rules, input type constraints, circular type references, and required root type presence.
• Validate a GraphQL schema before generating a client SDK
• Debug a 'must have at least one field' schema validation error
• Check input type constraints before adding a mutation
• Verify deprecated field directive syntax before publishing a schema change
Next step
Continue with Utility Matrix tools for the next decision in this workflow.
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FAQ
What does this tool tell you?
The GraphQL Schema Validator checks SDL schema syntax, non-null field rules, input type constraints, circular type references, and required root type presence.
What affects the result most?
SDL syntax validation: type definitions, field types, arguments, directives. Non-null rules: String! vs String — non-null fields must always resolve, cannot return null. Input type validation: input types cannot contain interfaces or unions.
How should I use the result?
Treat the tool's output as a first-pass check, not a proof of correctness. A clean pass means no issues in the patterns this tool recognizes; a failure points to a specific problem you can investigate in your source. The underlying spec is the authoritative source for edge cases.