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

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 ✅

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

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

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

⚠️ 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

Terminal 1 — start the proxy:

cd claude-code-proxy && python3 start_proxy.py

Terminal 2 — launch Claude Code:

export ANTHROPIC_BASE_URL="http://localhost:8082"

export ANTHROPIC_AUTH_TOKEN="anything"

claude --model claude-sonnet-4-5

That's it. Type hi to test. 🎉

Available Models

All free with GitHub Copilot:

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

• 📖 Full guide with copy buttons:
  itslokeshx.github.io/Claude-Code-For-Free
  


• ⭐ GitHub repo:
  github.com/itslokeshx/Claude-Code-For-Free
  


• 🔌 claude-code-proxy:
  github.com/fuergaosi233/claude-code-proxy
  

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