---
title: "Codex via Gateway"
description: "Configure Codex to use Vercel AI Gateway as a custom model provider, select a Gateway model, and keep the credential value out of the Codex configuration file."
canonical_url: "https://vercel.com/academy/ai-gateway/codex-with-gateway"
md_url: "https://vercel.com/academy/ai-gateway/codex-with-gateway.md"
docset_id: "vercel-academy"
doc_version: "1.0"
last_updated: "2026-08-08T23:27:13.552Z"
content_type: "lesson"
course: "ai-gateway"
course_title: "Using AI Gateway in Production"
prerequisites:  []
---

<agent-instructions>
Vercel Academy — structured learning, not reference docs.
Lessons are sequenced.
Adapt commands to the human's actual environment (OS, package manager, shell, editor) — detect from project context or ask, don't assume.
The lesson shows one path; if the human's project diverges, adapt concepts to their setup.
Preserve the learning goal over literal steps.
Quizzes are pedagogical — engage, don't spoil.
Quiz answers are included for your reference.
</agent-instructions>

# Codex via Gateway

# How Do I Run Codex Through the Gateway?

Codex supports custom model providers. A small configuration block gives it the Gateway endpoint and the name of the environment variable that holds your key.

\*\*Note: Quick Answer\*\*

Add a Vercel provider to the Codex configuration with the Gateway base URL and `AI_GATEWAY_API_KEY` as its `env_key`. Select that provider and a current Gateway model, then start Codex normally.

## Outcome

Run one read-only Codex task through a custom AI Gateway provider without storing the key in `config.toml`.

## Fast Track

1. Put the Gateway key in `AI_GATEWAY_API_KEY`
2. Add the provider block below to the Codex configuration
3. Start Codex in a throwaway repository and run a small task

## Hands-on exercise

Add a Vercel provider to `~/.codex/config.toml` for a personal default, or to `.codex/config.toml` in a trusted repository for a project-specific setting. Check the current Gateway catalog before choosing a model because model IDs change over time.

```toml filename="config.toml"
model_provider = "vercel"
model = "openai/gpt-5.6-sol"

[model_providers.vercel]
name = "Vercel AI Gateway"
base_url = "https://ai-gateway.vercel.sh/v1"
env_key = "AI_GATEWAY_API_KEY"
```

The file contains the environment variable's name, not its value. Set the real key in the shell or secret manager that starts Codex.

## Try It

Open Codex in a throwaway repository containing `demo.ts`, then ask:

```text
Explain demo.ts in three bullets. Do not modify anything.
```

Codex should complete the task with the configured provider. If startup fails, verify the TOML structure, confirm that `AI_GATEWAY_API_KEY` exists in the launching environment, and check that the selected model is still in the Gateway catalog.

## Done-When

- [ ] Codex starts with the Vercel provider selected
- [ ] The selected model exists in the current Gateway catalog
- [ ] Codex completes the read-only task
- [ ] The key value does not appear in `config.toml`, source control, or terminal output

## Solution

The provider block above is the complete Codex configuration. The file identifies the Gateway endpoint and credential variable while the launching environment supplies the secret.

## Related Questions

- [How do I run OpenCode through the Gateway?](/ai-gateway/stay-aware/opencode-with-gateway)
- [How do I run Claude Code through the Gateway?](/ai-gateway/stay-aware/claude-code-with-gateway)
- [How do I see where my money is going?](/ai-gateway/stay-aware/see-your-spend)


---

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