DeepSeek returned an authentication error:

Error: Invalid API key

Or your account has billing issues. Here is how to fix it.

Fix 1: Verify API key

Check your key is correct:

# Check if key is set
echo $DEEPSEEK_API_KEY

# Test the key
curl https://api.deepseek.com/v1/models \
  -H "Authorization: Bearer $DEEPSEEK_API_KEY"

Fix 2: Generate new key

If your key is invalid:

1. Go to platform.deepseek.com
2. Navigate to API Keys
3. Create a new key
4. Copy and save it

# Set new key
export DEEPSEEK_API_KEY="sk-..."

Fix 3: Check billing

Expired credit causes silent failures:

# Check account balance
curl https://api.deepseek.com/v1/usage \
  -H "Authorization: Bearer $DEEPSEEK_API_KEY"

Add credit at platform.deepseek.com/billing.

Fix 4: Fix key format

DeepSeek keys start with sk-:

# Wrong
api_key = "deepseek-..."

# Correct
api_key = "sk-..."

Fix 5: Check permissions

Some keys have restricted access:

# Test with full permissions key
curl https://api.deepseek.com/v1/chat/completions \
  -H "Authorization: Bearer $DEEPSEEK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"deepseek-v4-pro","messages":[{"role":"user","content":"test"}]}'

Fix 6: Verify endpoint

Use the correct API endpoint:

# Correct
client = openai.OpenAI(
    base_url="https://api.deepseek.com",
    api_key="sk-..."
)

# Wrong
client = openai.OpenAI(
    base_url="https://api.deepseek.com/v1",  # Don't add /v1
    api_key="sk-..."
)

Still not working?

1. Regenerate key — Create a fresh API key
2. Check email — Account verification may be required
3. Contact support — platform.deepseek.com/support
4. Use OpenRouter — Alternative access method

FAQ

How do I get a DeepSeek API key?

Go to platform.deepseek.com, create an account, navigate to API Keys, and create a new key. The key starts with sk- and should be kept secure.

Why is my API key not working?

Common causes: key is incorrect (check for typos), key has expired, account has no credit, or you are using the wrong endpoint. Verify the key at platform.deepseek.com/api-keys.

Can I use DeepSeek API for free?

DeepSeek offers a free tier with limited requests (10/minute). For higher usage, you need to add credit to your account. See our AI API Pricing guide for details.

Related: DeepSeek V4 Complete Guide · DeepSeek API Timeout Fix · AI API Pricing Compared 2026 · OpenRouter Complete Guide