GraphQL Tester
Test and debug GraphQL queries instantly with our free online GraphQL Tester. Write, validate, and execute GraphQL queries and mutations against any GraphQL endpoint with a clean, developer-friendly interface. This tool provides syntax highlighting, auto-completion, schema introspection, query variables support, and detailed error reporting. Whether you are learning GraphQL, developing a GraphQL API, or debugging production issues, this tester streamlines your workflow. Features include query history, customizable headers, response formatting, and the ability to explore the API schema interactively. Perfect for frontend developers consuming GraphQL APIs, backend developers building resolvers, and QA engineers validating API behavior.
What Is
The GraphQL Tester is an interactive web-based IDE for writing, validating, and executing GraphQL queries and mutations. It connects to any GraphQL endpoint over HTTP or WebSocket and provides a comprehensive development environment similar to GraphiQL or Postman. Key features include: real-time syntax highlighting with GraphQL-aware parsing and error detection, auto-completion based on the endpoint's introspected schema, a split-pane view with query editor on the left and formatted JSON response on the right, support for query variables and operation names, HTTP headers configuration for authentication and custom headers, schema documentation explorer showing all types, fields, queries, mutations, and subscriptions, query history with the ability to re-run recent queries, and response formatting with collapsible JSON tree view. The tool introspects the endpoint schema on connection to provide accurate type information and validation.
How to Use
- Open the GraphQL Tester in your browser — no installation or account required.
- Enter the GraphQL endpoint URL in the address bar at the top of the interface.
- Configure any required HTTP headers such as Authorization tokens or Content-Type for your endpoint.
- Introspect the schema by clicking the Docs or Schema tab to explore available types, queries, and mutations.
- Write your GraphQL query in the editor panel — use auto-completion and syntax highlighting to build accurate queries.
- Add any necessary query variables in the variables panel, then click the Execute button to send the request and view the formatted response.
Examples
Input: Query: { user(id:1) { name email posts { title } } }
Process: Parse query AST → Validate schema → Execute resolver → Return JSON
Result: {user:{name:John,email:[email protected],posts:[{title:Hello}]}}
Input: Mutation: createUser(input:{name:Alice}) { id }
Process: Validate input → Run mutation resolver → Insert record → Return new ID
Result: {createUser:{id:42}}
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Frequently Asked Questions
Is the GraphQL Tester free?
Yes, this tool is completely free to use with unlimited queries, no account required, and no premium features. You can test against any GraphQL endpoint, introspect schemas, and use all debugging features without any cost or usage restrictions.
Does it support all GraphQL features?
Yes, the tester supports queries, mutations, subscriptions, fragments, inline fragments, directives, variables, aliases, and all standard GraphQL syntax. It also supports schema introspection queries and documentation exploration. WebSocket connections are supported for real-time subscription testing.
What authentication methods are supported?
You can add any HTTP header needed for authentication, including Bearer tokens, API keys in headers, cookies, and custom authorization schemes. The headers are stored locally in your browser and sent with each request. We recommend using environment-specific endpoints and never committing credentials to version control.
Can I test against local or private endpoints?
Yes, you can connect to localhost endpoints (http://localhost:4000/graphql) and any network-accessible endpoint. For private APIs behind VPNs or firewalls, ensure the tool is running on a machine with network access to the endpoint. Some browsers may block mixed content (HTTP from HTTPS pages).
How does the auto-completion work?
Auto-completion uses the endpoint's introspection query to fetch the complete schema definition. It understands all types, fields, arguments, enums, and input types defined in the schema. Typeahead suggestions appear as you type, showing field names with their descriptions and expected argument types.
Is my API data secure when using this tool?
All queries are sent directly from your browser to the GraphQL endpoint — the tool acts as a client and does not proxy or store your data. No query content, headers, or responses are stored on any server. The tool may store your endpoint URL and headers locally in your browser for convenience, but this data never leaves your device.