If you use Janitor AI, SillyTavern, or build AI apps, you know the exact pain point: you get a new API key from a third-party provider (OpenRouter, a proxy, etc.), you paste it into your app, and... nothing happens.
Did the key fail? Is the Base URL wrong? Did you typo the model name? You end up wasting 20 minutes and a bunch of tokens just trying to get a "Hello World" response.
To solve this, I built AI API Tester.
It's a completely free, dark-mode web utility. You paste your Base URL, your API Key, and the Model Name. The backend sends a 1-token request to your endpoint and instantly tells you if it's working.
Try it out here: https://apitester123.netlify.app/
How it works:
-Frontend: Vanilla HTML/JS with a clean, dark-mode UI.
-Backend: Python with FastAPI.
-Networking: Uses httpx to send an async POST request to your {base_url}/chat/completions endpoint with a max_tokens: 1 payload.
It formats the errors nicely too—if your key is dead, it tells you 401: Invalid API Key. If your URL is wrong, it tells you 404: Not Found.
It's 100% free. If it saves you 10 minutes of debugging, there's a "Buy me a coffee" link at the bottom. Let me know what other features would be useful.
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