2026 Complete Guide: Install Codex Desktop & Connect to Third-Party APIs via CC Switch v3.17.0

Looking for a way to use OpenAI's Codex Desktop without official account login? This 2026 step-by-step guide is here to help. Whether you're a beginner or an experienced developer, you'll learn how to install Codex Desktop and connect it to third-party APIs like Fenno using CC Switch v3.17.0—all while enabling full features such as code review, multi-step task execution, and context-aware coding.

Codex Desktop is OpenAI's standalone AI programming agent launched in 2026, supporting Windows 10+, macOS 12+, and Linux systems. Its core capabilities include analyzing uncommitted code diffs for review, breaking down natural language tasks into cross-file actions, understanding project structure to generate consistent code, and supporting multiple models (gpt-5.4, gpt-5.4-mini) plus third-party integrations via the OpenAI Responses API. According to OpenAI's June 2026 blog, domestic platforms like MiniMax, Alibaba Cloud Bailian, Baidu Qianfan, and Volcano Ark have already adapted to this API format, making it easier for Chinese developers to access Codex.

Before starting, you'll need three tools: Codex Desktop (from OpenAI's official site), CC Switch v3.17.0 (an open-source API manager), and an API key from a compatible platform like Fenno.

Step 1: Get Fenno API Key
Log into the Fenno console, navigate to the "API Keys" section, and click "Create Key". Name it (e.g., "Codex"), select the "code-plan/Mini" group, set an optional usage limit (0 means no limit), then copy the generated sk- prefixed key. Note the endpoint: https://api.fenno.ai.

Step 2: Install CC Switch v3.17.0
CC Switch is an open-source (MIT license) API manager built with Tauri 2. Download the appropriate installer from its GitHub page: macOS users (Apple Silicon/Intel) get the .dmg file, Windows 10+ users can choose .deb (for WSL) or .exe, and Linux users pick the AppImage based on their architecture. Install and complete the initial setup.

Step 3: Import Fenno Config into CC Switch
Back to the Fenno console's API Keys page, find your new key and click "Import CCS". Verify the details: app type (Codex), supplier (Fenno), endpoint (https://api.fenno.ai), model (gpt-5.4), and auto usage query (every 30 minutes). Click "Import"—you'll see Fenno in CC Switch's supplier list with balance and usage data.

Step 4: Enable Fenno in CC Switch
Open CC Switch, click the GPT icon (for OpenAI tools), find Fenno in the supplier list, and toggle the switch to enable it. This routes Codex's requests through Fenno's API.

Step 5: Install Codex Desktop
Download Codex Desktop from chatgpt.com/codex, install it, and launch. Choose "Use other login method" to avoid ChatGPT account verification.

Step 6: Log into Codex with Fenno API Key
Copy your Fenno API key, paste it into Codex's API Key input field, enter the base URL (https://api.fenno.ai), and confirm. If successful, Codex's main interface loads, and the model name appears in the bottom left.

Once connected, you can use Codex to review uncommitted code (run "codex review --uncommitted" in terminal), execute natural language tasks (e.g., "Write unit tests for this Python function"), and switch between suppliers via CC Switch without restarting Codex. According to Juejin Community's July 2026 Codex third-party integration special topic, the response delay for code completion is similar to the official account mode, with minimal differences in task success rates.

Sources

• Aliyun Developer Article: https://developer.aliyun.com/article/1750531
• OpenAI Official Blog (June 2026)
• Juejin Community Codex Third-Party Integration Special Topic (July 2026)