2026 Complete Guide: Codex++ Download, Installation, and Integration with DeepSeek for Codex App
A step-by-step guide to using Codex++, an open-source enhancement tool for Codex App, including downloading, installing, and configuring it to connect...
Codex++ is an open-source third-party tool designed to enhance the Codex desktop application (Codex App). Unlike modifications that alter original installation files, it uses the Chromium DevTools Protocol (CDP) to dynamically inject enhancement scripts during runtime, ensuring its features remain functional even when Codex App receives version updates.
To use Codex++ for connecting Codex App to AI models like DeepSeek, you’ll need several prerequisites: a working installation of Codex App, Codex++ itself, an OpenAI API key, a DeepSeek API key, and at least one successful login to Codex App (using an OpenAI account or third-party logins like Google, Apple, or Microsoft).
For Windows users, the guide provides the Codex++ v1.2.4 installation package. The installation steps are straightforward: download the setup file, run it, choose a non-system drive (like D: instead of C:) for installation, follow on-screen prompts, and complete the setup. Two shortcuts will be created: one for the Codex++ management tool and another for launching the enhanced Codex App.
Obtaining an OpenAI API key involves logging into the OpenAI auth page, navigating to the API Keys section, creating a new secret key, naming it, copying the key (and saving it securely—once the page closes, it can’t be viewed again), then using this key to log into Codex App via the "Sign in another way" option.
To get a DeepSeek API key, visit the DeepSeek platform, log in (WeChat login is an option), go to the API keys section, create a new key, name it, copy and save it, then close the window. The key is now ready for Codex++ configuration.
Configuring Codex++ to connect to DeepSeek requires first exiting Codex App completely (including from the taskbar). Open the Codex++ management tool, which auto-detects Codex App’s location and version. Navigate to "Vendor Configuration", click "Add Vendor", and fill in details: name (e.g., DeepSeek), access mode (pure API), model (deepseek), base URL (https://api.deepseek.com), API key (your DeepSeek key), upstream protocol (Chat Completions), and context sizes as needed. After saving, test the connection by sending a "hi" message—an HTTP 200 response confirms success.
To use the enhanced Codex App, launch it via the Codex++ shortcut. The interface will show a Codex++ indicator with a green dot (signaling normal operation), and you can switch to DeepSeek models from the chat interface dropdown.
Important notes: Always use the Codex++ shortcut to access enhanced features (original Codex App only shows OpenAI models). When configuring vendors, refer to the model’s official documentation for correct base URLs and upstream protocols.
Common FAQs: If the Codex++ menu doesn’t appear, ensure you launched via the Codex++ shortcut and check the management tool’s diagnostic and log pages. The Upstream worktree feature in Codex++ differs from Codex’s native creation—it updates the remote branch first before creating a new worktree, starting from the latest remote tracking branch instead of the local HEAD.
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