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Lokesh
Lokesh

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How to Use Copilot Claude Sonnet & Opus models for Free Inside Claude Code (After VS Code Copilot Removed Them)

#github #githubcopilot #webdev #ai

GitHub quietly removed Claude Sonnet 4.5 and Opus 4.5 from the VS Code
Copilot extension. But here's what nobody is talking about — they're
still fully accessible through the Copilot API.

In this guide I'll show you exactly how to get Claude Sonnet 4.5 running
inside Claude Code CLI completely free using an open-source proxy.

Students pay $0. Everyone else pays $10/month for Copilot — still way
cheaper than Anthropic's API.

Why This Works

GitHub removed the models from the VS Code UI — not from their API.
The claude-sonnet-4.5 and claude-opus-4.5 models still respond
normally when called directly via api.githubcopilot.com.

We exploit this using three tools:

  • OpenCode CLI — authenticates with GitHub and stores your Copilot token
  • claude-code-proxy — translates Anthropic API → OpenAI API format
  • Claude Code CLI — Anthropic's agentic coding tool

The Architecture 

Claude Code CLI
      │  Anthropic format
      ▼
claude-code-proxy (localhost:8082)
      │  OpenAI format  
      ▼
api.githubcopilot.com
      │
      ▼
claude-sonnet-4.5 ✅
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Step 1 — Get GitHub Copilot Free (Students)

Visit education.github.com/pack and
verify with your .edu email or student ID. Approval takes 1–3 days.
GitHub Copilot is then permanently free on your account.

Not a student? Copilot is $10/month at github.com/features/copilot.

Step 2 — Install & Authenticate OpenCode 

curl -fsSL https://opencode.ai/install | bash
source ~/.bashrc
opencode auth login github
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A device code appears in your terminal. Go to github.com/login/device,
enter it, and authorize. Your token is now stored at
~/.local/share/opencode/auth.json.

Step 3 — Setup claude-code-proxy 

git clone https://github.com/fuergaosi233/claude-code-proxy
cd claude-code-proxy
pip install -r requirements.txt
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Create a .env file inside the folder:

OPENAI_API_KEY=your_token_from_auth.json
OPENAI_BASE_URL=https://api.githubcopilot.com
BIG_MODEL=claude-sonnet-4.5
MIDDLE_MODEL=claude-sonnet-4.5
SMALL_MODEL=claude-haiku-4.5
MAX_TOKENS_LIMIT=8096
REQUEST_TIMEOUT=300
PORT=8082
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⚠️ The URL must be https://api.githubcopilot.com — NOT with /v1
at the end. That causes a 404.

Step 4 — Launch Claude Code

Install Claude Code:

npm install -g @anthropic-ai/claude-code
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Terminal 1 — start the proxy:

cd claude-code-proxy && python3 start_proxy.py
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Terminal 2 — launch Claude Code:

export ANTHROPIC_BASE_URL="http://localhost:8082"
export ANTHROPIC_AUTH_TOKEN="anything"
claude --model claude-sonnet-4-5
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That's it. Type hi to test. 🎉

Available Models

All free with GitHub Copilot:

Model Notes
claude-sonnet-4.5 ★ Removed from VS Code
claude-opus-4.5 ★ Removed from VS Code
claude-haiku-4.5 Fastest Claude
gpt-4.1 Best speed/quality balance
gpt-4o Fast general purpose
gpt-5 Most powerful GPT
gemini-2.5-pro Long context

Switch models by changing BIG_MODEL in your .env and restarting
the proxy.

Common Issues

Token expired → Run opencode auth login github again and update
OPENAI_API_KEY in .env

404 error → Remove /v1 from OPENAI_BASE_URL

ECONNREFUSED → Proxy isn't running. Start it in Terminal 1 first.

Slow responses → Switch to gpt-4.1 for 3–5s responses instead
of 30s with Sonnet.

Resources

Drop any questions in the comments — happy to help! 👇

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