How to choose among the three AI tools—ChatGPT, Claude, and Gemini: one article that clearly explains what each is best at

I’ve been using the Claude API for a project recently, and all kinds of errors have been giving me a headache. After messing with it for several days, I organized the pitfalls I ran into, hoping it can help others who are stuck with the same issues.

Error 401 Unauthorized

This is the most common one; nine times out of ten it’s an API Key issue. Check whether the Key was copied completely—especially whether you missed the sk-ant- prefix at the beginning. Also, if the Key expired or was revoked, you’ll get this error too; just regenerate one in the Anthropic console.

Error 429 Rate Limit Exceeded

You’re being rate-limited because requests are too frequent. Free accounts can only make 60 requests per minute; paid accounts are higher. Solutions:

• Add a delay in your code, e.g., a 1-second interval between requests
• Use an exponential backoff strategy for retries
• Upgrade your plan to raise the limit

Error 529 Overloaded

Claude’s servers can’t handle the load; in this case, just wait a few minutes and try again. If it happens often, consider using it off-peak and avoid peak hours in North American time zones.

Error 400 Invalid Request

There’s something wrong with the request format. I once got this because I set max_tokens too high—Claude 3.5 Sonnet supports a maximum of 8192; go beyond that and it will fail. Also check whether your JSON is formatted correctly; even a missing comma won’t work.

Network connectivity issues

Users in mainland China often run into connection timeouts; there isn’t a great solution—either use a proxy or a relay service. In my testing, Hong Kong and Japan nodes are relatively stable.

If you run into payment issues when topping up API credits or subscribing to Claude Pro, you can check out Titikey—they have ready-made solutions so you don’t have to wrestle with credit cards and regional restrictions yourself.