GraphQL

Run queries, mutations, and subscriptions with schema introspection and type-safe variable editors.

Testnizer’s GraphQL editor understands the difference between HTTP-only endpoints and servers that support the graphql-ws subscription transport, and routes each operation type accordingly.

Multi-tab: URL, query, variables, headers, and response are stored per-tab. The introspected schema is shared across all tabs pointing at the same endpoint — introspect once, use everywhere.

Creating a GraphQL request

Click + New → GraphQL. The editor opens with an empty operation pane on the left, a variable editor below it, and a schema browser on the right.

Endpoint URL

Paste the GraphQL endpoint URL. Variables are supported:

{{apiBaseUrl}}/graphql

Headers

Add HTTP headers for the request, including authentication:

Authorization: Bearer {{accessToken}}
Content-Type: application/json   ← added automatically, override if needed

Operation editor

A Monaco instance with GraphQL syntax highlighting, bracket matching, and auto-complete powered by the introspected schema.

Write a query, mutation, or subscription:

query GetUser($id: ID!) {
  user(id: $id) {
    id
    email
    createdAt
    roles {
      name
    }
  }
}

Hit Send (or Ctrl+Enter). Testnizer detects the operation type:

• query / mutation → sent as HTTP POST (standard JSON body)
• subscription → connection upgraded to graphql-ws WebSocket transport

You can have multiple operations in the editor. Use the operation name dropdown in the toolbar to pick which one runs.

Variables tab

Edit JSON variables for the current operation:

{
  "id": "usr_01HXYZ"
}

The variable editor validates the JSON and highlights type mismatches against the schema when introspection is available.

{{environment}} variables resolve inside the JSON values:

{
  "id": "{{currentUserId}}"
}

Schema introspection

Click Introspect in the schema browser header. Testnizer sends the standard introspection query to the endpoint (using the current headers, so auth is automatically included) and builds the type browser from the result.

The type browser is searchable. Click any type to see its fields, arguments, and descriptions. Clicking a field in the type browser inserts it into the operation editor at the cursor position.

Introspection results are cached per endpoint + header combination and persist across app restarts. Hit Re-introspect to refresh.

If the server disables introspection (common in production), you can paste a schema SDL file directly:

1. Click Load schema from file in the schema browser
2. Pick a .graphql or .sdl file
3. Testnizer uses the file for auto-complete and type checking

Subscriptions

Testnizer automatically upgrades to a WebSocket connection when the operation is a subscription. The connection uses the graphql-ws protocol (Sec-WebSocket-Protocol: graphql-ws).

The subscription timeline behaves the same as the WebSocket editor — events appear as they arrive, you can pause, filter, and inspect individual payloads.

A Stop button appears while the subscription is active. Clicking it sends a complete message and closes the WebSocket. The connection also closes when you close the tab.

For servers that use the older subscriptions-transport-ws protocol, toggle the Legacy WS option in the request settings (gear icon).

HTTP details

For queries and mutations, the request is a POST with:

{
  "query": "...",
  "variables": { ... },
  "operationName": "GetUser"
}

The Console tab shows the raw HTTP request and response so you can verify exactly what was sent.

Persisted queries (APQ)

Turn on Automatic Persisted Queries in the request settings to send the query hash first and fall back to the full query on a PersistedQueryNotFound error. Testnizer handles the two-step exchange automatically.

Response

The response body is formatted JSON shown in Monaco. GraphQL errors[] in the response body are highlighted in the response pane — each entry shows the message and path (if present). This is separate from HTTP-level errors; a 200 OK response can still contain GraphQL errors.

The Headers and Console tabs are available for debugging network-level issues.

Cancelling in-flight requests

For queries and mutations, a Cancel button appears while the request is in flight. Clicking it sends a cancel signal to the engine; the tab returns to idle state immediately.