Copilot Chat's backdoor for Claude, Gemini, and 40+ others

What it does

Unify Chat Provider is a VS Code extension that registers external LLM APIs as models inside the native Copilot Chat sidebar. It translates between the editor’s Language Model API and provider-specific formats—OpenAI Chat Completions, Anthropic Messages, Gemini, Ollama, and others—so you can chat with Claude, DeepSeek, or a self-hosted instance without switching windows. The UI stays stock; only the backend endpoint changes.

The interesting bit

The extension treats free-tier quotas as a first-class feature. It can impersonate Claude Code clients, drain Gemini CLI and Antigravity allowances, and juggle multiple Copilot accounts, all through a visual configurator in the Command Palette. It is essentially premium glue code: a migration tool, format translator, and credential manager stuffed into one package.

Key highlights

• Supports OpenAI, Anthropic Messages, Gemini, Ollama, and OpenAI Responses API formats.
• Ships with tuned parameters for 200+ mainstream models to avoid manual tuning.
• One-click migration from other apps and extensions, plus Base64/JSON/URL config import and export.
• Allows multiple configuration variants for the same provider or model.
• Visual provider management through the native VS Code Command Palette.

Caveats

• Google Gemini CLI integration frequently hits permission errors that require manual Google Cloud project configuration, including enabling a specific API and supplying a Project ID.
• One-click setups for Google Antigravity and Claude Code impersonation carry explicit warnings that they may violate provider Terms of Service and risk account bans.
• The Nvidia provider may not automatically surface newer models like Kimi K2.5, forcing you to add them manually from the built-in list.

Verdict

Worth a look if you live in VS Code and want to consolidate LLM access inside Copilot Chat without paying for yet another ChatGPT subscription. Skip it if you already have a dedicated client you like or if routing proprietary API keys through a third-party extension makes you nervous.