--- title: "Codex with ChatGPT subscription in Visual Studio 2026 | iolys" description: "Use your eligible ChatGPT subscription for Codex in Visual Studio 2026. Choose models and effort, enable Fast mode, and track usage with iolys for C# and .NET." url: "https://getiolys.com/providers/codex" language: "en" updated: "2026-09-19" --- # Use Codex for C# and .NET in Visual Studio 2026. Bring the Codex AI coding agent into the IDE where your C# and .NET work already happens. iolys connects to the Codex CLI while keeping solution context, sessions, tool activity, and permissions visible in Visual Studio 2026. - Provider: Codex - Connection type: Provider CLI - Access: BYOS: use eligible ChatGPT subscription access - Who pays for the AI usage: Reuses an eligible AI subscription you already pay for through the provider's supported connection. - Where the model runs: The model runs in the provider's own cloud service. - Best for: Agentic refactors, repository-wide changes, code review, debugging, and implementation work across .NET solutions. - Official site: https://openai.com/codex/ Download and manage the Codex CLI locally from Manage Providers in iolys, then connect the account and plan you already use. When your ChatGPT plan includes Codex access, iolys can use that access inside Visual Studio 2026. ## How to connect Codex in Visual Studio 2026 1. Open Manage Providers in iolys and select Codex. 2. Download the CLI locally from the provider panel, then follow the account sign-in flow. Manage CLI versions and updates in the same place. 3. Choose your Codex model and start from the active Visual Studio 2026 solution. ## What you get - **Stay in Visual Studio 2026** — Keep Codex close to Solution Explorer, your editor, and the code you are changing. - **Preserve your workflow** — Switch to or from Codex without adopting another conversation interface. - **See every action** — Review tool calls, target files, and permission requests before sensitive work runs. ## Requirements iolys targets the Visual Studio 2026 IDE on 64-bit Windows. It requires access to a supported AI provider or a local Ollama instance. Git is required for isolated parallel workspaces. Visual Studio Code is a separate editor; iolys is an extension for the Visual Studio IDE. ## Price All currently available iolys features are free for personal and commercial use. AI provider subscriptions, API usage, and infrastructure costs remain separate. iolys does not include a bundled model allowance. ## Codex questions ### How can I use Codex in Visual Studio for C#? Install the iolys extension for Visual Studio 2026 and open your C# solution. Open Manage Providers in iolys and select Codex. Download the CLI locally from the provider panel, then follow the account sign-in flow. Manage CLI versions and updates in the same place. Choose your Codex model and start from the active Visual Studio 2026 solution. You can then ask Codex to help with your C# and .NET code from the iolys workspace. ### Is there a VSIX extension to use Codex in Visual Studio? Yes. iolys is a VSIX extension for Visual Studio 2026, and Codex is one of the provider connections it ships with. Install the iolys VSIX once from the Visual Studio Marketplace, then add Codex from the Manage Providers panel; there is no separate VSIX per provider. ### Can I use my ChatGPT subscription for Codex in iolys? Yes. Sign in with your ChatGPT account to use the Codex access included in your eligible subscription inside Visual Studio 2026. Your usage counts toward that plan’s Codex allowance. iolys provides the Visual Studio integration; your provider subscription remains with ChatGPT. ### Does Codex work in Visual Studio 2026? Yes, with the iolys extension. It connects the Codex CLI to a provider-independent workspace built for Visual Studio 2026. ### How is the Codex CLI installed and managed? Open Manage Providers in iolys. The Codex CLI is downloaded and managed locally from this panel, including its versions and updates. You do not need to install it separately before setting up the provider. ### Can I update or roll back the Codex CLI? Yes. In Manage Providers, select Codex to compare the installed and latest CLI versions. Choose a newer available release to update, or an earlier release from the version list to display the Downgrade to action. Selecting a version alone does not install it; you apply the change with the corresponding button. ### Do I need an OpenAI API key? Not necessarily. The Codex CLI can use eligible account-based access; API-key options remain available when that is the route you prefer. ### Can I see my Codex usage and banked resets in Visual Studio? Yes. Open Show usage from the iolys chat toolbar to see the usage percentage, reset times, and available usage resets reported by your Codex account, including their expiration dates. Reset availability depends on your account. ### Can I choose the model, reasoning effort, and Fast mode? Yes. Open the model options beside the prompt. iolys exposes the models, reasoning effort levels, and Fast mode options supported by your Codex connection. Availability depends on the selected model and account; Fast mode can increase usage. ### How do I give Codex context from Visual Studio? Type # to reference a file, or use the context menu to attach the active document or current selection. You can then ask Codex to explain code, investigate a bug, write tests, or help with a refactor. ### Can Codex search the web and generate images in iolys? Yes. The integration supports Codex’s native web search and image generation tools. Ask Codex to research a question, read relevant documentation, or create an image from a description, directly in your Visual Studio conversation. These work alongside the IDE tools provided by iolys. ### Can I switch away from Codex later? Yes. Provider switching is a core iolys workflow, so your Visual Studio 2026 experience remains consistent. ## Related pages - [Bring Your Own AI Subscription to Visual Studio 2026 | iolys](https://getiolys.com/) - [Bring Your Own Model (BYOM) in Visual Studio 2026 | iolys](https://getiolys.com/byom) - [AI coding agent capabilities for Visual Studio | iolys](https://getiolys.com/capabilities) - [Visual Studio integrations for C# and .NET | iolys](https://getiolys.com/integrations) - [GitHub Copilot alternative for Visual Studio and C# | iolys](https://getiolys.com/copilot-alternative-visual-studio) - [AI providers and BYOS for Visual Studio 2026 | iolys](https://getiolys.com/providers) - [What is iolys? AI coding agent harness for Visual Studio | iolys](https://getiolys.com/what-is-iolys) - [The story behind iolys | From iolite to AI in Visual Studio](https://getiolys.com/our-story) - [Install iolys from the Visual Studio Marketplace](https://marketplace.visualstudio.com/items?itemName=iolys.iolys-visual-studio) - [iolys blog](https://getiolys.com/blog)