Drop-in

Agent setup

Point Claude Code, Cursor, Codex, or a Gemini client at ModelMux. Authenticate with a customer mmux_ key from the dashboard. Upstream credentials never leave the gateway.

Public API

https://api.modelmux.xyz

Anthropic ANTHROPIC_BASE_URL is the origin without /v1
OpenAI / Cursor base_url includes /v1
Codex base_url includes /v1 and wire_api = "responses"

Claude Code

POST /v1/messages · origin must not end in /v1

export ANTHROPIC_BASE_URL=https://api.modelmux.xyz
export ANTHROPIC_API_KEY=mmux_YOUR_KEY
claude --model claude-sonnet-5

Claude Code (PowerShell)

Same variables, Windows session

$env:ANTHROPIC_BASE_URL = "https://api.modelmux.xyz"
$env:ANTHROPIC_API_KEY  = "mmux_YOUR_KEY"
claude --model claude-sonnet-5

OpenAI SDK

POST /v1/chat/completions · base_url includes /v1

export OPENAI_BASE_URL=https://api.modelmux.xyz/v1
export OPENAI_API_KEY=mmux_YOUR_KEY

Cursor

OpenAI-compatible override

Base URL: https://api.modelmux.xyz/v1
API key:  mmux_YOUR_KEY
Model:    openai/gpt-6-astra

Codex

~/.codex/config.toml — model and model_provider must sit above the table

model = "claude-sonnet-5"
model_provider = "modelmux"

[model_providers.modelmux]
name = "ModelMux"
base_url = "https://api.modelmux.xyz/v1"
env_key = "MODELMUX_API_KEY"
wire_api = "responses"

Codex env

Name must match env_key in config.toml

export MODELMUX_API_KEY=mmux_YOUR_KEY
codex

Gemini generateContent

x-goog-api-key or ?key=

POST https://api.modelmux.xyz/v1beta/models/claude-sonnet-5:generateContent
Header: x-goog-api-key: mmux_YOUR_KEY
# also accepted: Authorization: Bearer mmux_YOUR_KEY  or  ?key=

cURL · Chat Completions

Raw OpenAI wire format

curl https://api.modelmux.xyz/v1/chat/completions \
  -H "Authorization: Bearer mmux_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"claude-sonnet-5","messages":[{"role":"user","content":"hi"}]}'

Model ids

Accepted: claude-opus-5, claude-sonnet-5, claude-fable-5.1, z-ai/glm-5.3, gpt-6-astra, and the prefixed anthropic/ / openai/ variants.