DeepSeek

DeepSeek API Invalid Key Error — How to Fix It

The DeepSeek API returns an authentication error when your API key is missing, malformed, expired, or associated with an account that has a billing issue. This is one of the most common errors for developers new to the DeepSeek platform. The fix is usually quick once you identify which of the four root causes applies.

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Why does this error happen?

DeepSeek API keys are account-specific tokens that must be passed in the Authorization header of every request. Authentication failures occur when the key is copied incorrectly (with extra whitespace or missing characters), when the key has been revoked or rotated in the DeepSeek console, when the account's payment method has expired or the balance has run out, or when the key is being sent to the wrong API endpoint — for example, using an OpenAI-format key with the DeepSeek base URL without updating the key value.
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How to fix it

1

Regenerate Your API Key from platform.deepseek.com

Log into platform.deepseek.com, go to API Keys, and create a new key. Copy it immediately — it will not be shown again. Delete any old keys to avoid confusion. Paste the new key directly from the clipboard without retyping it to prevent character errors.

2

Check the Authorization Header Format

The correct format is: Authorization: Bearer sk-xxxxxxxxxxxxxxxx. Common mistakes include missing the word 'Bearer', adding extra spaces, or including the prefix 'sk-' twice. Verify your header matches this format exactly in your code or HTTP client.

3

Confirm You Are Using the Correct Base URL

The DeepSeek API base URL is https://api.deepseek.com — not the OpenAI URL. If you are using the OpenAI Python or Node SDK pointed at DeepSeek, set the base_url parameter to 'https://api.deepseek.com' explicitly. Using the wrong endpoint will always return an authentication error.

4

Check Your Account Balance and Billing

DeepSeek's API is credit-based. If your account balance reaches zero, API calls return an authentication-like error even with a valid key. Log into platform.deepseek.com, navigate to Billing, and top up your balance. New accounts may also need to add a payment method before any API calls succeed.

5

Store the Key in an Environment Variable

Never hardcode API keys in your source code. Use a .env file with DEEPSEEK_API_KEY=sk-xxx and load it with dotenv (Node) or python-dotenv (Python). This also prevents accidental key exposure in version control and makes key rotation trivial.

💡 Pro Tip

DeepSeek's API is OpenAI-compatible, meaning you can use the OpenAI SDK by simply changing baseURL and apiKey. This makes migration easy — but also means API key errors are easy to introduce by accidentally mixing credentials between providers.

Frequently Asked Questions

How do I know if my DeepSeek API key has expired?
DeepSeek API keys do not expire automatically, but they can be revoked manually from the platform console. If a key that was working suddenly stops, check platform.deepseek.com to confirm it is still active and has not been deleted or rotated.
Can I use my DeepSeek API key with third-party tools like LangChain or LlamaIndex?
Yes — since DeepSeek uses an OpenAI-compatible API format, most tools that support custom OpenAI endpoints will work. Set the base URL to https://api.deepseek.com and your DeepSeek API key in the relevant configuration field.
Why does my DeepSeek API key work in Postman but not in my code?
Check for invisible whitespace characters around the key in your environment variable or config file. Copy the key fresh from the platform console and paste it directly into a test request to confirm it works, then carefully transfer it to your code without extra characters.
Is there a free tier for the DeepSeek API that does not require billing setup?
DeepSeek offers limited free credits for new accounts, but you still need to create an API key. Once the free credits are exhausted, you must add a payment method to continue. Check your balance at platform.deepseek.com under Billing.
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Quick diagnostic checklist

Before diving into the full fix, run through these quick checks — they resolve the issue in most cases without additional steps:

1.Check DeepSeek service status — the platform experiences high demand spikes
2.Verify your API key is valid and has sufficient balance
3.Test with a shorter prompt to rule out token limit issues
4.Try the DeepSeek web chat to determine if the issue is API-specific
5.Check your account balance at platform.deepseek.com

Common root causes

Understanding why this error occurs helps you prevent it in the future. The most frequent causes are:

  • Server overload during high-demand periods
  • API key exhausted credit or invalid
  • Rate limits on the free API tier
  • Network latency to DeepSeek servers
  • Model-specific issues with R1 vs V3 endpoints

Still not working?

If none of the steps above resolved the issue, the next step is to contact DeepSeek support directly. When reaching out, include:

  • • The exact error message or code you see
  • • The steps you already tried from this guide
  • • Your account plan and the approximate time the error started
  • • Your browser/OS version if it is a web interface issue
Open DeepSeek API Docs →

About DeepSeek

DeepSeek is a Chinese AI research company that developed the DeepSeek-V3 and DeepSeek-R1 models. DeepSeek-R1 gained widespread attention for matching GPT-4-class performance at a fraction of the cost. The models are accessible via chat.deepseek.com and through a REST API.

Browse all DeepSeek error guides →

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