I have created an API key. But it is not working when I am using it on my web tool. I have created a worksheet generator web tool. But it is not working. Is the API free or payment based? Can anyone reply correctly about it?
No, the API is not free.
Perhaps all your answers are here (click and skip the Spanish…).
Please write in English.
I am unable to understand.
Click the quote and skip the Spanish part.
I’ll just copy everything (thanks _j 
):
Where’s API GPT-4? I subscribe for $20!
ChatGPT Plus does not offer any API credits or entitlements. API is a separate professional product for AI application development. Although you may have a gpt-4 powered chatbot in ChatGPT (and plus gives you plugins and more), ChatGPT Plus doesn’t unlock any API services or pay for any API bills.
API Overview
API allows programmers to develop applications for end users, and they are charged by the actual language data used by the service - the tokens sent and received by queries to the AI models. It is not free nor included with ChatGPT.
Where’s API GPT-4? I have a free API trial
You may have an API free trial credit if you created your OpenAI account recently, (three-month expiration after account creation). However, access to use gpt-4 services along with higher rate limits is only enabled after purchasing additional account credits, or having been billed monthly for actual non-free use.
A: Start a payment plan. Purchase credits to get gpt-4.
I’ve put in a credit card a while ago…
Your older API account with monthly billing can get gpt-4 access. Just having put in a card doesn’t qualify it though.
A monthly post-pay plan can be made eligible for gpt-4 access by actually incurring billing to the card from use (OpenAI currently doesn’t bill for small balances, like under a dollar). After you get a bill charged to your credit card (processed in first half of the following month), you should get gpt-4 access.
A: Use services, get billed
I put in a card a while ago, can I get it faster?
One can “cancel payment plan”, removing all cards, and then you’ll likely be only offered the ability to buy pre-paid credits, of $5-$100. A pre-pay, purchasing credits, instantly gets gpt-4. Once doing so, there is no going back to a monthly plan; you must always prepay and have a credit balance to use services. A second account for this is recommended if you need the original account’s features.
Do I already have API GPT-4?
Look in the list of models in your API account’s rate limits. It will be there.
Look in the API playground. Select mode “chat”. It will be there.
I don’t know anything about programming…
API is not meant for consumers: don’t put API keys into web sites, apps, extensions, or unknown software. You wouldn’t hand out your bank password?