Use Claude desktop app with llmapi.cheap

Run Claude desktop app on Gemini 3.8 Flash, Claude Sonnet 4.6, Claude Opus 4.6 or GPT-OSS with a single llmapi.cheap key. Plans start at $2 a month, and there is a free one-hour trial.

Protocol: Anthropic Messages · Config: ~/Library/Application Support/Claude-3p/configLibrary (macOS)

Fastest: one command

The setup command finds Claude desktop app on your machine, writes its configuration with your key and sets Gemini 3.8 Flash (high) as the default model. It needs no Node.js. Sign up first: your key is created automatically, and the dashboard shows this command with the key already filled in.

macOS / Linux

curl -fsSL https://llmapi.cheap/install.sh | sh

Windows (PowerShell)

irm https://llmapi.cheap/install.ps1 | iex

Manual setup

The setup command writes this for you, on macOS, Windows and Linux. To do it by hand: Help → Troubleshooting → Enable Developer Mode, then Developer → Configure Third-Party Inference → Gateway. Chat, Cowork and Claude Code inside the app all use it.

Gateway base URL:  https://llmapi.cheap
API key:           YOUR_API_KEY
Auth scheme:       bearer

Quit and reopen the app, then pick an llmapi model from the model menu. Windows keeps the file under %LOCALAPPDATA%\Claude-3p\configLibrary, Linux under ~/.config/Claude-3p/configLibrary.

Endpoints

Use the base URL that matches the protocol your tool speaks.

OpenAI: https://llmapi.cheap/v1
Anthropic: https://llmapi.cheap
Gemini: https://llmapi.cheap/v1beta
Models: https://llmapi.cheap/v1/models

Model IDs

Any of these work wherever Claude desktop app asks for a model name. Gemini 3.8 Flash (high) is the default the setup command picks.

Model ID	Model
`gemini-3.8-flash-high`	Gemini 3.8 Flash, high reasoning (default)
`gemini-3.8-flash`	Gemini 3.8 Flash, medium reasoning
`gemini-3.8-flash-low`	Gemini 3.8 Flash, low reasoning
`gemini-3.1-pro-high`	Gemini 3.1 Pro, high reasoning
`gemini-3.1-pro-low`	Gemini 3.1 Pro, low reasoning
`gemini-3-flash`	Gemini 3 Flash
`claude-sonnet-4-6`	Claude Sonnet 4.6
`claude-opus-4-6`	Claude Opus 4.6
`gpt-oss-120b`	GPT-OSS 120B

Troubleshooting

401 / invalid key: check the key starts with sk-llm- and has no extra spaces. Create a new one under Dashboard → API keys if needed.
Model not allowed: the free trial covers the Gemini models; Claude and GPT-OSS come with any paid plan.
404 on requests: OpenAI-style tools need https://llmapi.cheap/v1; Anthropic-style tools need https://llmapi.cheap without /v1.