AI API Key Tester

Not sure if your API key works? APIMaster's free API key tester lets you verify any OpenAI-compatible key—check validity, balance, and whether you're getting genuine model responses.

Test Your API Key Now

Go to APIMaster.ai API Key Tester to test any key instantly in your browser—no signup required.

What the API Key Tester Checks

1. Key validity: is the key syntactically correct and accepted by the provider?
2. Account balance: does the account have funds for API calls?
3. Model access: which models does this key have permission to call?
4. Response authenticity: is the model returning genuine AI output (not a cached or fake response)?

Test Your Key with Python

from openai import OpenAI

def test_api_key(api_key: str, base_url: str = "https://apimaster.ai/v1") -> dict:
    """Test an API key and return status info."""
    client = OpenAI(api_key=api_key, base_url=base_url)
    
    results = {}
    
    # Test 1: List models (lightweight check)
    try:
        models = list(client.models.list())
        results["valid"] = True
        results["model_count"] = len(models)
        results["models"] = [m.id for m in models[:5]]
    except Exception as e:
        results["valid"] = False
        results["error"] = str(e)
        return results
    
    # Test 2: Make a minimal API call
    try:
        response = client.chat.completions.create(
            model="gpt-4o-mini",
            messages=[{"role": "user", "content": "Reply with 'ok'"}],
            max_tokens=5,
        )
        results["callable"] = True
        results["response"] = response.choices[0].message.content
    except Exception as e:
        results["callable"] = False
        results["call_error"] = str(e)
    
    return results

# Test your key
result = test_api_key("YOUR_API_KEY")
print(result)

Testing for Claude API Key Validity

import anthropic

def test_claude_key(api_key: str, base_url: str = "https://apimaster.ai") -> bool:
    """Test a Claude (Anthropic) API key."""
    client = anthropic.Anthropic(api_key=api_key, base_url=base_url)
    try:
        response = client.messages.create(
            model="claude-haiku-4-5",
            max_tokens=5,
            messages=[{"role": "user", "content": "Say 'ok'"}],
        )
        print(f"✅ Key valid. Response: {response.content[0].text}")
        return True
    except anthropic.AuthenticationError:
        print("❌ Invalid key")
        return False
    except anthropic.APIStatusError as e:
        print(f"⚠️ API error: {e.status_code} - {e.message}")
        return False

test_claude_key("YOUR_CLAUDE_KEY")

Why API Keys Fail

Error	Meaning	Fix
401 Unauthorized	Key is invalid or expired	Get a new key from console
403 Forbidden	Key lacks permission for this model	Check key scope/tier
429 Too Many Requests	Rate limit hit	Wait or upgrade tier
402 Payment Required	Account has no balance	Top up account
400 Bad Request	Wrong base_url or request format	Check endpoint

Verify You're Getting Real Claude (Not a Fake)

Some API resellers substitute cheaper models while charging for premium ones. APIMaster's fingerprint detection system verifies model authenticity weekly.

How it works:

1. We send carefully crafted "fingerprint prompts" that only real Claude/GPT/DeepSeek respond to in specific ways
2. We analyze response patterns to confirm model identity
3. Results are published publicly at https://apimaster.ai/detect

# Quick manual test: does the model respond correctly to anthropic-specific prompts?
response = client.chat.completions.create(
    model="claude-sonnet-4-6",
    messages=[{"role": "user", "content": "Who made you? Reply in exactly 3 words."}],
)
# Real Claude should say something like "Anthropic made me"
print(response.choices[0].message.content)

Batch Testing Multiple Keys

import concurrent.futures

def test_key_quick(key_info):
    api_key, label = key_info
    client = OpenAI(api_key=api_key, base_url="https://apimaster.ai/v1")
    try:
        client.models.list()
        return label, "✅ valid"
    except Exception as e:
        return label, f"❌ {type(e).__name__}"

keys_to_test = [
    ("sk-key1...", "Production"),
    ("sk-key2...", "Staging"),
    ("sk-key3...", "Testing"),
]

with concurrent.futures.ThreadPoolExecutor(max_workers=5) as pool:
    for label, status in pool.map(test_key_quick, keys_to_test):
        print(f"{label}: {status}")

Get a Verified API Key

If your current key isn't working—or you want confirmed authentic Claude/GPT access—get a key from APIMaster:

Test API keys → · Get API key → · View verification data →