--- description: Route OpenAI Codex through AI Gateway using a custom model provider that points at the OpenAI endpoint. title: OpenAI Codex image: https://developers.cloudflare.com/og-docs.png --- [Skip to content](#main-content) > Documentation Index > Fetch the complete documentation index at: https://developers.cloudflare.com/ai-gateway/llms.txt > Use this file to discover all available pages before exploring further. # OpenAI Codex Last updated Aug 5, 2026|Copy as Markdown|[View as Markdown](https://developers.cloudflare.com/ai-gateway/integrations/coding-agents/openai-codex/index.md)|[Agent setup](https://developers.cloudflare.com/agent-setup/) [OpenAI Codex ↗](https://developers.openai.com/codex/) is a coding agent you run in your terminal. It supports [custom model providers ↗](https://developers.openai.com/codex/config-advanced#custom-model-providers) defined in `config.toml`. This configuration adds a provider that points at AI Gateway's [OpenAI endpoint](https://developers.cloudflare.com/ai-gateway/usage/providers/openai/), so Codex sends its requests through AI Gateway. AI Gateway authenticates the model provider for you through [Unified Billing](https://developers.cloudflare.com/ai-gateway/features/unified-billing/), so you pass a Cloudflare API token instead of an OpenAI API key. If your gateway is protected by Cloudflare Access, refer to [Use with Cloudflare Access](#use-with-cloudflare-access). Note Codex custom providers only support the OpenAI Responses API (`wire_api = "responses"`). This means you can only use OpenAI models that support the Responses API, such as `gpt-5.5`. Models from other providers (for example, Anthropic or Google) do not use the OpenAI Responses request format, so they do not work with Codex through this configuration. ## Prerequisites Before you start, you need: * Your Cloudflare account ID. To find it, refer to [Find your account and zone IDs](https://developers.cloudflare.com/fundamentals/account/find-account-and-zone-ids/). * An AI Gateway. You can use your account's `default` gateway or [create a gateway](https://developers.cloudflare.com/ai-gateway/get-started/) and use its slug. * A [Cloudflare API token](https://developers.cloudflare.com/fundamentals/api/get-started/create-token/) with `AI Gateway` permission. * [Credits loaded](https://developers.cloudflare.com/ai-gateway/features/unified-billing/#load-credits) on your account for third-party models. * [Codex ↗](https://developers.openai.com/codex/cli/) installed and updated to the latest version. 1. Create a Codex [profile ↗](https://developers.openai.com/codex/config-advanced#profiles) file at `~/.codex/cloudflare-aig.config.toml`. The profile defines a custom model provider that points at your gateway's OpenAI endpoint and reads your Cloudflare API token from an environment variable. Replace `` and `` with your values. You can use `default` for the gateway to route through your account's default gateway, or change it to another gateway slug. ```toml model_provider = "cloudflare-ai-gateway" model = "gpt-5.5" model_reasoning_effort = "medium" [model_providers.cloudflare-ai-gateway] name = "Cloudflare AI Gateway" # Run `wrangler whoami` to get your account ID, then replace . # Use `default` for to route through your account's default gateway. base_url = "https://gateway.ai.cloudflare.com/v1///openai" env_key = "CLOUDFLARE_API_KEY" wire_api = "responses" ``` Note Codex does not expand environment variables inside `base_url`, so the account ID and gateway slug must be literal values. Only `CLOUDFLARE_API_KEY` is read from the environment. 2. Set your Cloudflare API token as the `CLOUDFLARE_API_KEY` environment variable. The following commands set it for the current session. To persist it, add it to your shell profile (for example, `~/.zshrc` or `~/.bashrc`). Replace `` with your value. ```bash # Run `wrangler auth token` to get an auth token. export CLOUDFLARE_API_KEY="" ``` ```powershell # Run `wrangler auth token` to get an auth token. $env:CLOUDFLARE_API_KEY = "" ``` 3. Start Codex with the profile and send a prompt. Requests now route through AI Gateway. The `cloudflare-aig` profile name matches the `cloudflare-aig.config.toml` file you created. ```bash codex --profile cloudflare-aig ``` ## Use with Cloudflare Access If your gateway is protected by [Cloudflare Access](https://developers.cloudflare.com/ai-gateway/configuration/cloudflare-access/), Codex can authenticate with a short-lived Access token instead of a Cloudflare API token. Point the provider at your [custom domain](https://developers.cloudflare.com/ai-gateway/configuration/custom-domains/), and configure the provider's `auth` command to fetch the token with [cloudflared](https://developers.cloudflare.com/cloudflare-one/access-controls/authenticate-agents/#make-requests-with-cloudflared-access-curl) instead of passing a token through an environment variable. Update the same `~/.codex/cloudflare-aig.config.toml` profile from the Unified Billing setup so the provider points at your custom domain and uses `cloudflared` for authentication. The `cloudflare-aig` in `codex --profile cloudflare-aig` refers to this file's name. Replace `ai-gateway.example.com` with your custom domain. ```toml model_provider = "cloudflare-ai-gateway" model = "gpt-5.5" model_reasoning_effort = "medium" [model_providers.cloudflare-ai-gateway] name = "Cloudflare AI Gateway" base_url = "https://ai-gateway.example.com/openai" wire_api = "responses" [model_providers.cloudflare-ai-gateway.auth] command = "cloudflared" args = ["access", "login", "--no-verbose", "https://ai-gateway.example.com"] timeout_ms = 30000 refresh_interval_ms = 0 ``` Compared to the Unified Billing setup in the previous section, the custom domain replaces the account ID and gateway ID in `base_url`, and the `auth` block replaces `env_key`. Start Codex with the profile: ```bash codex --profile cloudflare-aig ``` The first request opens your identity provider's login flow. After you authenticate, requests route through AI Gateway with your Access identity attached as [cf.user\_id](https://developers.cloudflare.com/ai-gateway/observability/custom-metadata/#reserved-metadata). To confirm traffic reaches AI Gateway, refer to [Verify it works](https://developers.cloudflare.com/ai-gateway/integrations/coding-agents/#verify-it-works). Was this helpful? YesNo ## On this page [![](https://developers.cloudflare.com/_astro/logo.te5VL_aD.svg)Docs](https://developers.cloudflare.com/) ```json {"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/ai-gateway/integrations/coding-agents/openai-codex/#page","headline":"OpenAI Codex · Cloudflare AI Gateway docs","description":"Route OpenAI Codex through AI Gateway using a custom model provider that points at the OpenAI endpoint.","url":"https://developers.cloudflare.com/ai-gateway/integrations/coding-agents/openai-codex/","inLanguage":"en","image":"https://developers.cloudflare.com/og-docs.png","dateModified":"2026-08-05","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}} ```