Configuring Codex CLI With Custom Keys

Configuring Codex CLI With Custom Keys | Generated by AI

Home 2026.02

Question: How to use my own key with Codex CLI and how to use the OpenRouter API with it?

Answer:

Codex CLI is OpenAI’s open-source terminal-based coding agent (released around 2025). It acts like an interactive AI that can read your codebase, suggest/edit files, run commands, and iterate on tasks — all from your terminal.

It supports multiple providers (including OpenAI and third-parties like OpenRouter) via configuration.

1. Installation (macOS/Linux recommended; Windows experimental)

# Requires Node.js ≥ 18
npm install -g @openai/codex

Alternative install methods (Rust binary, brew, etc.) → check official docs.

2. Using your own OpenAI key (official / default way)

Option A – Easiest (interactive login)

Run once:

codex

→ Browser opens → sign in with ChatGPT account (Plus/Pro/… includes access)
or choose “Use API key” and paste your OpenAI API key from https://platform.openai.com/api-keys

Option B – Headless / script-friendly (env variable)

export OPENAI_API_KEY="sk-..."
codex

It caches the token after first use.

3. Using OpenRouter API (third-party models, often cheaper / more options)

Codex CLI supports custom providers via ~/.codex/config.toml (created automatically after first run).

Recommended config for OpenRouter (2026 working setup):

Edit (or create) the file:

# ~/.codex/config.toml

model = "anthropic/claude-4-sonnet"          # or deepseek/deepseek-r1, qwen/qwen2.5-coder-32b, google/gemini-2.5-pro, etc.
model_provider = "openrouter"                # ← important: must match the section name below

[model_providers.openrouter]
name = "OpenRouter"
base_url = "https://openrouter.ai/api/v1"
env_key = "OPENROUTER_API_KEY"               # ← reads from this env var
# Optional extra headers (sometimes needed)
# headers = { "HTTP-Referer" = "https://your-site.com", "X-Title" = "Codex CLI" }

Then set your key:

export OPENROUTER_API_KEY="sk-or-v1-..."
codex

Or make it permanent (zsh/bash):

echo 'export OPENROUTER_API_KEY="sk-or-v1-..."' >> ~/.zshrc
source ~/.zshrc

Quick test command (non-interactive):

codex "Explain the architecture of this project"

or start interactive session and just type natural language requests.

4. Popular models to try via OpenRouter in Codex CLI (Feb 2026)

deepseek/deepseek-r1 or deepseek/deepseek-v3-0324 — best price/performance coding
anthropic/claude-4-sonnet or claude-3.7-sonnet — highest quality
qwen/qwen2.5-coder-32b-instruct — very strong & cheap
google/gemini-2.5-pro — huge context, multimodal
openai/o3-mini or openai/o1 — strong reasoning

Just change the model = "..." line and restart codex.

5. Useful flags / modes

codex --suggest                # only propose changes, never apply automatically
codex --approval-policy never  # auto-apply (careful!)
codex --sandbox-mode workspace-write  # safer file writing
codex "fix bug in login flow"  # one-shot

Tip: Many users report better reliability + lower cost with OpenRouter + strong open models vs default OpenAI in Codex CLI.

If you run into “model_not_found” → double-check model_provider matches the [model_providers.xxx] section name exactly.

References:

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