AI Coding Tools Complete Guide: Use Cursor, Cline & Aider with One API Key

#ai #vscode #productivity #tutorial

The Problem

In 2026, AI coding tools are essential. Cursor, Cline, Aider, Continue... but each requires separate API keys and different configurations.

This guide shows you how to use one API key across all AI coding tools, accessing 624+ models and switching freely.

Why an API Gateway?

Problem	Example
Key management chaos	Separate keys for OpenAI, Anthropic, Google, DeepSeek
Scattered billing	Different dashboards per provider
Per-tool config	Set up keys separately in Cursor and Cline
Model switching friction	Changing providers means changing SDKs

We'll use Crazyrouter — fully OpenAI-compatible, 624+ models, one key.

Common Setup

# Add to ~/.bashrc or ~/.zshrc
export OPENAI_API_KEY="sk-your-crazyrouter-key"
export OPENAI_API_BASE="https://crazyrouter.com/v1"
export OPENAI_BASE_URL="https://crazyrouter.com/v1"

1. Cursor

Open Cursor → Settings → Models
Enter API key in OpenAI API Key
Set Override OpenAI Base URL to https://crazyrouter.com/v1
Add models, save

Recommended:

Use Case	Model	Why
Tab completion	`gpt-4o-mini`	Fast & cheap
Chat	`claude-sonnet-4-20250514`	Best code understanding
Composer	`deepseek-chat`	Best value

Pro tip: No need for Cursor Pro ($20/mo). Your own API key enables AI features on the free tier.

2. Cline (VS Code)

Install "Cline" from marketplace
Settings → API Provider → OpenAI Compatible
Enter:

Base URL: https://crazyrouter.com/v1
API Key:  sk-yourkey
Model ID: claude-sonnet-4-20250514

Task-based model selection:

Complex refactoring  → claude-sonnet-4-20250514
Daily coding         → deepseek-chat ($0.14/1M tokens)
Bug fixes            → gpt-4o-mini (fast)
Algorithm problems   → deepseek-reasoner

3. Continue (VS Code / JetBrains)

Edit ~/.continue/config.json:

{
  "models": [
    {
      "title": "Claude Sonnet",
      "provider": "openai",
      "model": "claude-sonnet-4-20250514",
      "apiBase": "https://crazyrouter.com/v1",
      "apiKey": "sk-yourkey"
    },
    {
      "title": "DeepSeek V3",
      "provider": "openai",
      "model": "deepseek-chat",
      "apiBase": "https://crazyrouter.com/v1",
      "apiKey": "sk-yourkey"
    }
  ],
  "tabAutocompleteModel": {
    "title": "Tab Autocomplete",
    "provider": "openai",
    "model": "gpt-4o-mini",
    "apiBase": "https://crazyrouter.com/v1",
    "apiKey": "sk-yourkey"
  }
}

4. Aider (Terminal)

pip install aider-chat

# Uses env vars from common setup
aider --model deepseek-chat              # Best value
aider --model claude-sonnet-4-20250514   # Best quality
aider --model gpt-4o                     # Balanced

Cost Optimization

Complexity	Model	Cost (in/out per 1M tokens)
High	claude-sonnet-4	$3 / $15
High	gpt-4o	$2.5 / $10
Medium	deepseek-chat	$0.14 / $0.28 ← recommended
Low	gpt-4o-mini	$0.15 / $0.60

100 AI assists/day, monthly cost:

Model	Monthly
deepseek-chat	~$0.13
gpt-4o-mini	~$0.59
gpt-4o	~$9.75
claude-sonnet-4	~$13.50

Recommended setup (under $5/month):

Tab completion:   gpt-4o-mini
Daily coding:     deepseek-chat
Important review: claude-sonnet-4

Python Script Usage

from openai import OpenAI

client = OpenAI(
    base_url="https://crazyrouter.com/v1",
    api_key="sk-yourkey"
)

response = client.chat.completions.create(
    model="deepseek-chat",
    messages=[
        {"role": "system", "content": "You are a senior engineer. Review code and suggest improvements."},
        {"role": "user", "content": "Review this:\n\n```

python\ndef fibonacci(n):\n    if n <= 1: return n\n    return fibonacci(n-1) + fibonacci(n-2)\n

```"}
    ]
)
print(response.choices[0].message.content)

Summary

Tool	Config	Difficulty
Cursor	Settings → Models	⭐ Easy
Cline	Sidebar → Settings	⭐ Easy
Continue	~/.continue/config.json	⭐⭐ Medium
Aider	Env vars	⭐ Easy
Python	pip install openai	⭐ Easy