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.
No data is transmitted — everything runs locallyTool
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
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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.