n8n HTTP Request JSON Body Examples

If an API expects JSON, the most common setup problems are usually not “n8n problems”: they are invalid JSON, values with the wrong type, missing authentication headers, or a body shape that does not match the API.

1. Basic POST JSON body

Suppose an API expects a name, age and active flag:

{
  "name": "Alice",
  "age": 18,
  "active": true
}

Notice that 18 is a number and true is a boolean. Writing them as "18" or "true" changes their type.

2. Nested JSON

{
  "customer": {
    "email": "a@example.com",
    "plan": "pro"
  }
}

Nested objects are useful when an API groups related fields under objects such as customer, metadata or options.

3. Common headers

Content-Type: application/json
Authorization: Bearer YOUR_TOKEN

The exact authentication header depends on the API. When n8n has a dedicated credential type for the service, keeping the secret in n8n Credentials is generally safer than pasting a long-lived token directly into a workflow field.

4. A cURL equivalent

curl -X POST 'https://api.example.com/v1/items' \
  -H 'Content-Type: application/json' \
  -H 'Authorization: Bearer YOUR_TOKEN' \
  --data '{"name":"Alice","active":true}'

If the cURL request fails too, the problem is probably the API endpoint, authentication, headers or payload rather than the n8n workflow wiring.

5. Debugging checklist

• 400 Bad Request: verify required fields, JSON shape and value types.
• 401 Unauthorized: verify the token and the authentication scheme expected by the API.
• 403 Forbidden: the credential may authenticate successfully but lack permission for that action.
• 415 Unsupported Media Type: check the request body's content type and format.
• 429 Too Many Requests: check the API's rate-limit rules and add appropriate retry/backoff behavior.

6. When to use the HTTP Request node

n8n documents the HTTP Request node as the fallback for API operations that are not covered by a dedicated app node. The exact options depend on the target API, so always compare the generated request with that API's current documentation.

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