Generating Realistic Mock Data for API Development

Why Realistic Mock Data Matters

Generating test data with "test", "foo", "123" hides bugs that only appear with real-world inputs — names with unicode characters, emails with plus-aliases, phone numbers with country codes.

Realistic mock data surfaces edge cases early, makes demos more convincing, and saves hours of manual fixture creation.

What the API Generates

• People — names, emails, phone numbers, addresses (locale-aware)
• Internet — URLs, IPs, user agents, slugs
• Finance — credit card numbers (Luhn-valid but not real), IBANs
• Dates — past, future, relative ranges
• Text — lorem ipsum, sentences, paragraphs
• IDs — UUID, Nanoid, ULID

Basic Usage

curl -X POST https://api.toolkitapi.io/v1/devtools/mock-data \
  -H "X-API-Key: $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "count": 5,
    "schema": {
      "id":    { "type": "uuid" },
      "name":  { "type": "name" },
      "email": { "type": "email" },
      "score": { "type": "integer", "min": 0, "max": 100 }
    }
  }'

Response:

[
  { "id": "550e8400...", "name": "Elena Voss", "email": "[email protected]", "score": 74 },
  ...
]

Locale Support

Pass "locale": "de_DE" to generate German names and addresses, "locale": "ja_JP" for Japanese, etc.

Seeded Randomness

Pass "seed": 42 to get deterministic output. The same seed always produces the same data — useful for snapshot tests.

Integration with Pytest

import httpx, pytest

@pytest.fixture(scope="session")
def mock_users():
    r = httpx.post(
        "https://api.toolkitapi.io/v1/devtools/mock-data",
        headers={"X-API-Key": API_KEY},
        json={"count": 20, "schema": {"name": {"type": "name"}, "email": {"type": "email"}}, "seed": 1},
    )
    return r.json()

This keeps your test fixtures realistic without maintaining static JSON files.