GraphQL query syntax lint

GraphQL Query Syntax Lint helps you check GraphQL queries and schema definition language (SDL) for parsing and syntax issues using the official GraphQL parser. It is useful when you want to catch malformed queries before they reach an API, CI pipeline, or production client. Developers, QA teams, API integrators, and schema authors use syntax validation to reduce avoidable request failures, improve editor feedback, and confirm that a query or schema document is structurally valid. This validator is focused on parsing and syntax-level correctness, not authorization, business logic, or runtime execution behavior.

How This Validator Works

This tool sends your GraphQL text through a standards-based parser and checks whether the document can be parsed successfully. If the input is a query, mutation, subscription, fragment, or SDL schema definition, the parser evaluates the token structure, punctuation, nesting, and document grammar. When the parser encounters an issue, it typically returns a location-specific error that helps you identify the exact line and column where the syntax breaks.

• Checks GraphQL document structure against parser rules
• Identifies syntax errors such as invalid tokens, missing braces, or malformed fields
• Supports both executable GraphQL operations and SDL-style schema text
• Helps validate content before deployment, testing, or code review

Common Validation Errors

GraphQL syntax errors usually come from small formatting or grammar mistakes. These issues are often easy to miss in long queries or generated documents, especially when fragments, variables, aliases, or nested selections are involved.

• Unclosed braces or parentheses in nested selections or variable definitions
• Missing colons in field arguments, input objects, or schema definitions
• Invalid names such as unsupported characters in field or type identifiers
• Unexpected tokens caused by stray commas, quotes, or punctuation
• Broken SDL syntax in type, interface, enum, union, input, or directive definitions
• Fragment or operation structure errors such as incomplete selection sets

Where This Validator Is Commonly Used

GraphQL syntax validation is commonly used anywhere queries or schemas are written, reviewed, generated, or shipped. It is especially valuable in development workflows where fast feedback helps prevent invalid documents from reaching downstream systems.

• Frontend applications that build GraphQL queries dynamically
• API development and schema design workflows
• CI checks for generated queries or schema files
• Code editors, IDE plugins, and linting pipelines
• Documentation sites and examples that need verified GraphQL snippets
• Testing environments for client libraries and API integrations

Why Validation Matters

Syntax validation helps teams catch errors early, before they become failed requests, broken builds, or confusing runtime issues. In GraphQL, a document that cannot be parsed will not execute, so validating structure first saves time during development and debugging. It also improves consistency across teams by making sure queries and schemas follow the same grammar rules, which is especially important in shared APIs and automated tooling.

Technical Details

This validator uses the official GraphQL parser to parse the provided text. That means it focuses on the language grammar defined by GraphQL rather than custom application rules. The result is a syntax-level check that can be applied to both query documents and SDL. It does not validate whether fields exist on a schema, whether arguments are semantically correct, or whether a query is authorized by a server.

Frequently Asked Questions

What does GraphQL syntax validation check?

It checks whether your GraphQL document follows the language grammar and can be parsed successfully. That includes braces, parentheses, field structure, variable definitions, fragments, and SDL syntax. It does not determine whether the query will return data or whether the schema contains the requested fields.

Does this tool validate GraphQL queries and schema definitions?

Yes. It can be used for executable GraphQL operations as well as SDL schema text. That makes it useful for validating client queries, server-side schema files, and generated GraphQL documents before they are committed or deployed.

Is syntax validation the same as schema validation?

No. Syntax validation only checks whether the text is grammatically correct. Schema validation usually means checking whether a query matches a known schema, including field names, argument types, and return types. Those are separate checks and often require schema-aware tooling.

Why would a valid-looking GraphQL query still fail?

A query can look correct at a glance but still contain a small grammar issue such as a missing brace, invalid token, or malformed fragment. Parser-based validation helps catch these problems early and often provides a precise line and column for troubleshooting.

Can this help with generated GraphQL documents?

Yes. Generated queries, fragments, and SDL often contain formatting or templating mistakes that are hard to spot manually. Running them through a parser-based validator is a practical way to confirm that the output is structurally valid before it is used in tests or production.

Does this tool check authorization or security issues?

No. It does not evaluate permissions, access control, or server-side security rules. It only checks syntax. Security review for GraphQL usually requires additional controls such as authentication, authorization, query depth limits, rate limiting, and server-side monitoring.

What are the most common GraphQL syntax mistakes?

Common mistakes include missing braces, incorrect punctuation, invalid names, broken variable definitions, and incomplete selection sets. These errors are especially common in long queries, copied examples, or documents assembled from templates and fragments.

Is SDL supported by the same parser?

Yes. SDL is part of the GraphQL language ecosystem and can be parsed by the official GraphQL parser. That makes it useful for validating type definitions, enums, inputs, directives, unions, interfaces, and schema extensions.

Should I use this before CI or deployment?

Yes, syntax validation is a good early step in a development pipeline. It helps catch malformed GraphQL documents before they fail in tests, break builds, or reach a server. Many teams use parser checks as part of local development, pre-commit hooks, and CI jobs.

Related Validators & Checkers

• JSON Validator — useful when GraphQL variables or API payloads are stored as JSON
• XML Validator — helpful for systems that still exchange structured data in XML
• API Response Validator — checks whether returned data matches expected structure
• Schema Validator — useful for validating structured definitions across formats
• Syntax Checker — broader text parsing checks for developer workflows