Chapter 2: Hands-On API Setup - Building Your Multi-Model Command Centre (2026)

⏱️ Estimated time: 90 minutes 🎯 Difficulty: Beginner-friendly 💡 What you'll achieve: Direct access to 5+ leading AI models via Claude Code and VS Code

Your Journey to AI Mastery

Transform from AI consumer to AI commander. We'll set up multiple providers, configure Claude Code and your editor, and start saving money immediately.

Setup path through OpenAI, Anthropic, Google Gemini and free models, finishing as a multi-model user

Preparation Checklist

Before we begin:

VS Code open and running
Claude Code CLI or Continue extension installed
Internet browser ready
Email access for verifications
90 minutes of focused time
Credit/debit card for API billing (start with $5-10)

💡 Tip: You'll spend ~$3-5/month vs £60/month for subscriptions. The ROI is immediate!

Option A: Claude Code (Recommended for 2026)

Claude Code is Anthropic's AI coding agent. It runs in your terminal, understands your entire project, and can read, write, and run code on your behalf. It is also available as a desktop app, a web app at claude.ai/code, and as extensions for VS Code and JetBrains.

Setting Up Claude Code

# Install Claude Code globally (requires Node.js 18+)
npm install -g @anthropic-ai/claude-code

# Verify installation
claude --version

# Launch Claude Code in your project directory
cd your-project
claude

On first launch, Claude Code will walk you through authentication with your Anthropic account. It uses Claude Sonnet 4.6 by default — use /fast inside a session for quicker responses.

Key Features to Know

CLAUDE.md — drop a CLAUDE.md file in your project root to give Claude Code persistent instructions about your codebase
Slash commands — /fast for speed, /cost to check spend, /model to switch models
MCP servers — connect external tools (databases, APIs, browsers) via the Model Context Protocol
Hooks — automate actions before/after tasks (linting, testing, formatting)
Subagents — Claude Code can spawn background agents for parallel work

Test Your Setup

# Start a session and ask something
claude

# Inside the session, try:
> Explain what an API is in two sentences
> /fast
> Now explain it again (this response will be faster)

Option B: Continue Extension (Alternative for VS Code)

Continue is a free, open-source extension that connects VS Code to multiple AI providers. It is a good option if you want a model-switcher inside your editor alongside Claude Code.

Opening Continue Settings

Click the Continue icon in the VS Code sidebar (>>)
Click the gear icon (settings)
config.json opens automatically

Complete 2026 Configuration

{
  "models": [
    {
      "title": "Claude Sonnet 4.6 ⭐",
      "provider": "anthropic",
      "model": "claude-sonnet-4-6",
      "apiKey": "YOUR_ANTHROPIC_KEY"
    },
    {
      "title": "Claude Opus 4.8 (Premium)",
      "provider": "anthropic",
      "model": "claude-opus-4-8",
      "apiKey": "YOUR_ANTHROPIC_KEY"
    },
    {
      "title": "Claude Haiku 4.5 (Fast)",
      "provider": "anthropic",
      "model": "claude-haiku-4-5",
      "apiKey": "YOUR_ANTHROPIC_KEY"
    },
    {
      "title": "GPT-4o",
      "provider": "openai",
      "model": "gpt-4o",
      "apiKey": "YOUR_OPENAI_KEY"
    },
    {
      "title": "GPT-4o Mini (Cheap)",
      "provider": "openai",
      "model": "gpt-4o-mini",
      "apiKey": "YOUR_OPENAI_KEY"
    },
    {
      "title": "o3 (Reasoning)",
      "provider": "openai",
      "model": "o3",
      "apiKey": "YOUR_OPENAI_KEY"
    },
    {
      "title": "Gemini 2.5 Flash ⚡",
      "provider": "gemini",
      "model": "gemini-2.5-flash",
      "apiKey": "YOUR_GEMINI_KEY"
    },
    {
      "title": "Gemini 2.5 Pro (2M Context)",
      "provider": "gemini",
      "model": "gemini-2.5-pro",
      "apiKey": "YOUR_GEMINI_KEY"
    },
    {
      "title": "Llama 4 (Free via Groq)",
      "provider": "groq",
      "model": "llama-4-70b",
      "apiKey": "YOUR_GROQ_KEY"
    }
  ],
  "tabAutocompleteModel": {
    "title": "Haiku 4.5 Autocomplete",
    "provider": "anthropic",
    "model": "claude-haiku-4-5",
    "apiKey": "YOUR_ANTHROPIC_KEY"
  },
  "embeddingsProvider": {
    "provider": "openai",
    "model": "text-embedding-3-small",
    "apiKey": "YOUR_OPENAI_KEY"
  }
}

📝 Note: Check each provider's documentation for current model IDs — they update regularly.

Provider Setup Guide (2026 Edition)

1. OpenAI (GPT-4o, o3)

Why start here?

Industry standard
Reliable performance
Great documentation
Wide model selection

Step-by-Step Setup

A. Create Account

Visit: https://platform.openai.com/signup
Sign up with email or Google
Verify email address

B. Get API Key

Go to: https://platform.openai.com/api-keys
Click "Create new secret key"
Name it: "VS Code - Workshop 02"
Copy key immediately (starts with sk-proj-...)

⚠️ Critical: You can't view this key again after closing!

C. Set Up Billing

Navigate to: https://platform.openai.com/settings/organization/billing
Add payment method
Set monthly limit: Start with $10
Enable usage alerts at 50% and 80%

D. Understand Tiers

Tier	How to Reach	Benefits
Free	Default	3 RPM, 40K TPM
Tier 1	Spend $5	500 RPM, 200K TPM
Tier 2	Spend $50	5,000 RPM, 2M TPM
Tier 3	Spend $1,000	Higher limits

💡 Tip: You'll automatically upgrade as you spend. Start small!

2. Anthropic (Claude Fable 5 / Opus 4.8 / Sonnet 4.6 / Haiku 4.5)

Why add Claude?

Best-in-class writing quality and coding assistance
Full model range from Haiku (fast/cheap) to Fable (most capable)
200K context window (all models)
Claude Code — a standalone AI coding agent for your terminal
Agent SDK for building custom AI agents

Setup Steps

A. Create Account

Visit: https://console.anthropic.com
Sign up with email
Verify email

B. Get API Key

Navigate to: API Keys section
Click "Create Key"
Name: "Workshop 02"
Copy key (starts with sk-ant-api03-...)

C. Add Credits

Go to Billing
Add $10 minimum
Set auto-refill (optional)

D. Current Models

Model	Speed	Use Case
Fable 5	Standard	Latest and most capable
Opus 4.8	Standard	Top-tier reasoning
Sonnet 4.6	Fast	Best balance of speed/quality/cost ⭐
Haiku 4.5	Fastest	High volume, cheapest

Check console.anthropic.com for current pricing.

🎯 Recommendation: Start with Sonnet 4.6 for most tasks — it offers the best balance of quality, speed, and cost.

3. Google (Gemini 2.5 Flash/Pro)

Why add Gemini?

Massive 1M-2M context windows
Very competitive pricing
Generous free tier available
Excellent multimodal capabilities (text, images, video, audio)

Setup Steps

A. Get Free API Key

Visit: https://aistudio.google.dev/apikey
Sign in with Google account
Click "Create API Key"
Select "Create API key in new project"
Copy key (starts with AIzaSy...)

B. Free Tier Limits

Google offers a generous free tier — check aistudio.google.dev for current limits (typically 15+ RPM, 1.5M+ tokens/day).

💡 Tip: Gemini's free tier is VERY generous. Perfect for experimentation!

C. Enable Pay-as-you-go (Optional)

Go to Google Cloud Console
Enable billing
Activate Gemini API
Set budget alerts

D. Model Comparison

Model	Context	Special Feature
2.5 Flash	1M	Fastest, cheapest
2.5 Pro	2M	Entire codebases!

Check aistudio.google.dev for current pricing.

🎯 Use case: Gemini 2.5 Pro can analyse your ENTIRE project in one prompt!

4. Groq (Free Fast Inference)

Why add Groq?

Free tier with generous limits
Ultra-fast inference (150+ tokens/sec)
Access to Llama 4 and other open models
No credit card required

Setup Steps

A. Create Account

Visit: https://console.groq.com
Sign up (no payment needed!)
Verify email

B. Get API Key

Go to API Keys
Create new key
Copy (starts with gsk_...)

C. Free Tier Limits

30 requests per minute
14,400 tokens per minute
14,400 tokens per day

⚠️ Note: Lower daily limits, but FAST. Perfect for quick tasks!

D. Available Models

Groq's model lineup changes frequently. Check console.groq.com for the latest available models. Typical offerings include Llama 4 variants and other popular open-source models.

5. Together AI (Optional - More Open Models)

Bonus provider for advanced users:

Visit: https://api.together.xyz
Sign up, get $5 free credits
Access 50+ open-source models
Pay-as-you-go after credits

Testing Your Multi-Model Setup

Quick Test Protocol

Create test-models.md:

# Multi-Model API Test

## Prompt
Explain quantum computing in exactly 2 sentences.

### Claude Sonnet 4.6:
[Select prompt, Ctrl+I, choose model, test]

### GPT-4o:
[Test here]

### Gemini 2.5 Flash:
[Test here]

### Llama 4 (Groq):
[Test here]

## Speed Test Results
- Fastest: ___
- Most detailed: ___
- Most natural: ___

Model Comparison Exercise

Test each model with:

Creative task: "Write a haiku about coffee"
Technical task: "Explain async/await in JavaScript"
Analysis task: "List pros/cons of remote work"

📝 Note: Notice how models differ in style, speed, and depth!

Cost Monitoring Setup

OpenAI Dashboard

Visit: https://platform.openai.com/usage
View real-time costs
Set up email alerts

Anthropic Console

Visit: https://console.anthropic.com/settings/billing
Monitor credit balance
Set auto-refill threshold

Create Cost Tracking Spreadsheet

# AI API Cost Tracking - June 2026

| Date | OpenAI | Anthropic | Google | Groq | Total | Notes |
|------|--------|-----------|--------|------|-------|-------|
| Jan 25 | $0.12 | $0.08 | $0.00 | $0.00 | $0.20 | Blog posts |
| Jan 26 | $0.05 | $0.15 | $0.01 | $0.00 | $0.21 | Code review |

## Monthly Budget
- Target: $10/month
- Current: $0.41
- Remaining: $9.59

## Model Preferences
- Writing: Claude Sonnet 4.6 (best prose)
- Coding: Claude Sonnet 4.6 or GPT-4o
- Research: Gemini 2.5 Pro (massive context)
- Quick tasks: Haiku 4.5 or GPT-4o-mini
- Free testing: Llama 4 via Groq

Security Best Practices (2026 Edition)

Environment Variables Method

Step 1: Create .env file

# In your project root
touch .env

Step 2: Add keys

# .env file
OPENAI_API_KEY=sk-proj-abc123...
ANTHROPIC_API_KEY=sk-ant-api03-xyz...
GOOGLE_API_KEY=AIzaSy...
GROQ_API_KEY=gsk_...

Step 3: Add to .gitignore

# .gitignore
.env
.env.local
*.key

Step 4: Reference in config

{
  "models": [
    {
      "title": "Claude Sonnet",
      "provider": "anthropic",
      "model": "claude-sonnet-4-6",
      "apiKey": "${ANTHROPIC_API_KEY}"
    }
  ]
}

API Key Rotation Schedule

📅 Recommended schedule:

Every 90 days: Rotate all keys
Monthly: Review usage patterns
Weekly: Check spending
Daily: Monitor for unusual activity

Productivity Shortcuts

Continue Extension Shortcuts

Shortcut	Action
`Ctrl+I` (Windows/Linux)	Open AI chat
`Cmd+I` (Mac)	Open AI chat
`Ctrl+Shift+M`	Switch model
`Ctrl+L`	Clear conversation

Custom Commands (Advanced)

{
  "customCommands": [
    {
      "name": "improve",
      "prompt": "Improve this text for clarity, professionalism, and impact",
      "description": "Enhance writing quality"
    },
    {
      "name": "summarize",
      "prompt": "Summarize this in 3 concise bullet points",
      "description": "Quick summary"
    },
    {
      "name": "explain-code",
      "prompt": "Explain this code line-by-line for a beginner",
      "description": "Code explanation"
    },
    {
      "name": "refactor",
      "prompt": "Refactor this code for better readability and performance",
      "description": "Improve code quality"
    },
    {
      "name": "tests",
      "prompt": "Generate comprehensive unit tests for this code",
      "description": "Create test suite"
    }
  ]
}

Troubleshooting Common Issues

Error: "Invalid API Key"

Solutions:

✅ Check for extra spaces when copying
✅ Ensure key hasn't been revoked
✅ Verify billing is set up
✅ Try regenerating key

Error: "Rate Limit Exceeded"

Solutions:

⏸️ Wait 60 seconds
🔄 Switch to different model/provider
📊 Check usage dashboard
💳 Upgrade tier if needed frequently

Error: "Model Not Found"

Solutions:

📝 Check model name spelling
🔄 Update to latest model IDs
📚 Consult provider documentation
⬆️ Update Continue extension

Error: "Context Length Exceeded"

Solutions:

✂️ Trim conversation history
📉 Reduce input text size
🔄 Switch to model with larger context (Gemini 2.5 Pro)
🧹 Clear old messages

Your Achievements Unlocked!

You Now Have:

✅ Multi-Model Access: 5+ leading AI models at your fingertips ✅ Cost Control: 90% savings vs subscriptions ✅ Direct Integration: No more copy-paste workflows ✅ Model Comparison: Know which AI excels at what ✅ Professional Setup: Enterprise-grade configuration ✅ Security: Proper API key management

Before vs After

Before: one model at 20 pounds a month via a web interface. After: eight or more models for 3 to 5 pounds a month, integrated in your IDE

Next Steps

🎯 Immediate: Test each model with real work tasks 📊 This week: Track costs for 7 days 🧪 Ongoing: Experiment with different models for different tasks

Pro Tips

Bookmark all provider dashboards
Export your config.json as backup
Document which models work best for your needs
Set calendar reminder for 90-day key rotation
Join communities: r/ClaudeAI, r/OpenAI for tips

Next: Chapter 3: Practical Exercises - Model Mastery

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