Common JSON Patterns: API Responses, Configs, and More

JSON is flexible enough to represent almost any data structure, but a handful of patterns appear in the vast majority of real-world applications. Recognizing them makes it faster to read unfamiliar JSON and design your own APIs and config files.

Pattern 1: List of objects (API responses)

The most common pattern — an array of uniform objects. Used by almost every REST API list endpoint. Each object has the same keys, making it easy to loop through and render in a table or list.

JSON

[
  {"id": 1, "name": "Alice", "email": "[email protected]", "role": "admin"},
  {"id": 2, "name": "Bob", "email": "[email protected]", "role": "viewer"}
]

When returned by an API, this is usually wrapped in an envelope:

JSON

{
  "data": [
    {"id": 1, "name": "Alice"},
    {"id": 2, "name": "Bob"}
  ],
  "meta": {
    "page": 1,
    "perPage": 20,
    "total": 2
  }
}

Pattern 2: Nested configuration

Objects inside objects for grouping related settings. This pattern is ubiquitous in config files — package.json, tsconfig.json, Docker Compose, and countless application configs all use it.

JSON

{
  "database": {
    "host": "localhost",
    "port": 5432,
    "name": "mydb",
    "ssl": true
  },
  "features": {
    "darkMode": true,
    "notifications": false,
    "betaFeatures": ["ai-search", "bulk-export"]
  },
  "logging": {
    "level": "info",
    "format": "json"
  }
}

Pattern 3: Key-value lookup (dictionary)

A flat object used as a map from key to value. Great for lookup tables: currency exchange rates, HTTP status code descriptions, i18n translations, or feature flags.

JSON

{
  "USD": 1.0,
  "EUR": 0.92,
  "GBP": 0.79,
  "JPY": 149.50
}

i18n translations:

JSON

{
  "welcome": "Welcome back, {name}!",
  "logout": "Sign out",
  "error.notFound": "Page not found"
}

Pattern 4: Polymorphic list with type discriminator

When a list can contain objects of different shapes, add a type field so consumers know how to handle each item:

JSON

[
  {"type": "text", "content": "Hello world"},
  {"type": "image", "url": "https://example.com/photo.jpg", "alt": "A photo"},
  {"type": "video", "url": "https://example.com/clip.mp4", "duration": 30}
]

Pattern 5: Tree / recursive structure

A node that can contain children of the same shape. Used for navigation menus, file system trees, org charts, and comment threads.

JSON

{
  "id": 1,
  "label": "Root",
  "children": [
    {
      "id": 2,
      "label": "Branch A",
      "children": [
        {"id": 4, "label": "Leaf 1", "children": []},
        {"id": 5, "label": "Leaf 2", "children": []}
      ]
    },
    {
      "id": 3,
      "label": "Branch B",
      "children": []
    }
  ]
}

Pattern 6: Event / log record

A flat object with a timestamp, event type, and payload. Used in event-driven systems, audit logs, and analytics pipelines.

JSON

{
  "timestamp": "2024-01-15T09:32:47Z",
  "event": "user.login",
  "userId": "usr_abc123",
  "ip": "192.168.1.1",
  "metadata": {
    "browser": "Chrome",
    "os": "macOS"
  }
}

Try it in JSON Prism

Paste any of these patterns into the JSON Formatter to explore the structure. Need realistic sample data? The JSON Mock Generator creates JSON that matches any of these patterns so you can test your code without calling a real API.