How to use OpenAI API Key for AI chat
Ann Ng
OpenAI (ChatGPT)About OpenAI (ChatGPT)
Latest models available:
- GPT-5: Flagship model for advanced reasoning, coding, multimodal, and agentic tasks. 400K context, highest intelligence, supports text and vision.
- GPT-5 mini: Cost-efficient, high-performance version. 400K context, excels at text and vision, fast and suitable for scaled deployments.
- GPT-5 nano: Ultra-fast, most cost-effective GPT-5 model. 400K context, designed for lightweight and high-volume tasks.
- GPT-4.1: Best non-reasoning model for legacy and resource-sensitive applications.
Key features:
- 400K token context window (all GPT-5 models)
- 128K max output tokens
- Advanced agentic tool use with reasoning and verbosity controls
- Real-time voice interaction (via ChatGPT)
- Multimodal input: text, images, and documents
- Highly improved coding and frontend engineering capabilities
- Personalized experiences (customization, connectors, study mode)
- Enhanced reliability & safety
Step by step guide to use OpenAI API Key to chat with AI
1. Get Your OpenAI API Key
First, you'll need to obtain an API key from OpenAI. This key allows you to access their AI models directly and pay only for what you use.
- Visit OpenAI's API console
- Sign up or log in to your account
- Navigate to the API keys section
- Generate a new API key (copy it immediately as some providers only show it once)
- Save your API key in a secure password manager or encrypted note
2. Connect Your OpenAI API Key on TypingMind
Once you have your OpenAI API key, connecting it to TypingMind to chat with AI is straightforward:
- Open TypingMind in your browser
- Click on the "Settings" icon (gear symbol) in the sidebar
- Navigate to "API Keys" section
- Find the OpenAI (ChatGPT) configuration area
- Paste your API key in the designated OpenAI field
- Click "Save" to verify the key works and store your configuration
3. Start Chatting with OpenAI models
Now you can start chatting with OpenAI (ChatGPT) models through TypingMind:
- Select your preferred OpenAI model from the model dropdown menu
- Start typing your message in the chat input
- Enjoy faster responses and better features than the official interface
- Switch between different AI models as needed
GPT-5- Use specific, detailed prompts for better responses (How to use Prompt Library)
- Create AI agents with custom instructions for repeated tasks (How to create AI Agents)
- Use plugins to extend OpenAI capabilities (How to use plugins)
- Upload documents and images directly to chat for AI analysis and discussion (Chat with documents)
4. Monitor Your AI Usage and Costs
One of the biggest advantages of using API keys with TypingMind is cost transparency and control. Unlike fixed subscriptions, you pay only for what you actually use. Visit https://platform.openai.com/usage to monitor your OpenAI API usage and set spending limits.
| Feature | OpenAI Subscription Plans | Using OpenAI API Keys |
|---|---|---|
| Cost Structure | ❌ Fixed monthly fee Pay even if you don't use it ChatGPT Plus:$20/month ChatGPT Pro:$200/month | ✅ Pay only for actual usage $0 when you don't use it |
| Usage Limits | ❌ Hard daily/hourly caps You have to wait for the next period to use it again | ✅ Unlimited usage No limits. Only limited by your budget |
| Model Access | ❌ Platform decides available models Old models get discontinued | ✅ Access to all API models Including older & specialized versions |
- Use less expensive models for simple tasks
- Keep prompts concise but specific to reduce token usage
- Use TypingMind's prompt caching to reduce repeat costs (How to enable prompt caching)
- Using RAG (retrieval-augmented generation) for large documents to reduce repeat costs (How to use RAG)
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