Cursor has become the go-to IDE for AI-assisted development. But the built-in API credits run out fast, and using your own Anthropic API key at official rates gets expensive quickly.
Here’s how to set up Cursor with a cheap Claude API key that saves you up to 96% on costs.
Why Use a Custom API Key in Cursor?
Cursor’s built-in Pro plan gives you limited “fast” requests. Once those run out, you’re either waiting for slow requests or paying per-token at official rates.
With a relay API key from BusinessAgent:
- Unlimited fast requests (based on your credit balance)
- Claude Opus 4.6 at $24 instead of $100 (76% savings)
- Codex 5.3 High at $4 instead of $100 (96% savings)
- Same model quality — identical responses, just cheaper
Step-by-Step Setup
1. Get Your API Key
Contact us to get your BusinessAgent API key:
- Telegram: @zhoumo_828
- WeChat: Moumlbius
You’ll receive a key that looks like: sk-ba-xxxxxxxxxxxx
2. Open Cursor Settings
Press Cmd + , (Mac) or Ctrl + , (Windows/Linux) to open Settings, then navigate to Models.
3. Configure the API Endpoint
Set these values:
| Setting | Value |
|---|---|
| Override OpenAI Base URL | https://business-agent.cc/api |
| API Key | Your sk-ba-... key |
4. Select Your Model
Choose your preferred model:
- Claude Opus 4.6 — Best for complex refactoring and architecture decisions
- Codex 5.3 High — Best for day-to-day coding tasks (most cost-effective)
- Sonnet 4.6 — Good balance of speed and intelligence
5. Test It
Open any file and try:
- Select some code
- Press
Cmd + K(inline edit) orCmd + L(chat) - Ask it to refactor, explain, or write new code
If you get a response, you’re all set! 🎉
Agent Mode Configuration
Cursor’s Agent Mode (Cmd + I) also works with custom API keys. For the best experience:
- Go to Settings → Features → Agent
- Ensure Agent Mode is enabled
- The same API key and endpoint work for Agent Mode
Pro tip: Use Codex 5.3 for routine tasks in Agent Mode and switch to Opus 4.6 only for complex multi-file refactors. This can reduce your costs by another 50%.
Troubleshooting
”Authentication Failed”
- Double-check your API key — make sure you copied it completely
- Ensure the base URL is exactly
https://business-agent.cc/api(no trailing slash)
“Model Not Found”
- Make sure you’re selecting a supported model (Opus 4.6, Codex 5.3, Sonnet 4.6)
- The model name in Cursor should match exactly
Slow Responses
- Check your internet connection
- Try switching to a different model temporarily
- Our average latency is <200ms, so if it’s consistently slow, reach out to support
Cost Comparison for Cursor Users
Here’s what a typical developer spends on Cursor in a month:
| Usage Level | Official API | With BusinessAgent | Monthly Savings |
|---|---|---|---|
| Light (5K requests) | ~$50 | $2-12 | $38-48 |
| Medium (15K requests) | ~$150 | $6-36 | $114-144 |
| Heavy (50K requests) | ~$500 | $20-120 | $380-480 |
Also Works With
The same API key and endpoint work with:
- Claude Code (CLI)
- VS Code (Continue extension)
- JetBrains (AI Assistant)
- MCP Server
- Any OpenAI-compatible tool
Get Started
Ready to supercharge your Cursor setup?
- Get your API key: Telegram or WeChat (Moumlbius)
- Set up in 5 minutes using the guide above
- Start coding with Claude Opus 4.6 at 76-96% less
Visit business-agent.cc for full pricing details.