These examples use the website API host, which currently lists their recommended models. The direct API host can have a different catalog during rollouts. For larger requests or longer runtimes, use https://api.nano-gpt.com/api/v1 with a model from that host’s catalog. See API Hosts for limits and availability checks.

Codex CLI

Use OpenAI’s Codex CLI with NanoGPT to access GPT 6.1 Sol, Claude Opus 5.5, Gemini Flash Latest, and 400+ AI models through a single API key.

Get started with NanoGPT for pay-as-you-go pricing with no monthly fees. Add credits and start coding immediately.

NanoGPT provides an OpenAI API-compatible endpoint that works seamlessly with Codex CLI. This allows you to:

Use Codex CLI with your NanoGPT credits
Access OpenAI models (GPT 6.1 Sol and more) without a separate OpenAI account
Route to 400+ other models including Claude Opus 5.5, Gemini Flash Latest, and GLM Latest

Step 1: Install Codex CLI

Recommended Installation Method
Cursor Guided Installation Method

Prerequisites: Node.js 22 or newer

# Install Codex CLI
npm install -g @openai/codex

# Navigate to your project
cd your-awesome-project

# Start Codex
codex

If you are not familiar with npm but have Cursor, you can enter the command in Cursor, and Cursor will guide you through the installation.

https://developers.openai.com/codex/cli/ Help me install Codex CLI

Note: If you encounter permission issues during installation, try using sudo (macOS/Linux) or running the command prompt as an administrator (Windows) to re-execute the installation command.

Step 2: Configure NanoGPT

Get API Key

Go to NanoGPT API
Create an account or log in
Copy your API key

Configure Codex

Set up Codex using one of the following methods:

One-Click Setup (Mac/Linux)
Manual Configuration (All Platforms)
Environment Variables Only (Quick)

Run this command in your terminal:

curl -O "https://nano-gpt.com/install/codex_nanogpt.sh" && bash ./codex_nanogpt.sh

The script will:

Prompt for your API key
Create ~/.codex/config.toml using a model available to your API key on the configured API host
Add NANOGPT_API_KEY to your shell profile

The installer now supports browser-based login. When the script starts, choose:

Browser login (recommended) - it will open a verification URL, wait for approval, and then save your key in ~/.codex/config.toml.
Paste API key - manual fallback if you prefer.

If a browser does not open automatically, copy the printed URL into your browser and approve the request.For local or self-hosted testing, NANOGPT_BASE_URL keeps login and API traffic on the same origin. To override only the Codex API endpoint, set NANOGPT_API_BASE_URL to the complete versioned base URL, including /api/v1 (for example, https://api.nano-gpt.example/api/v1).For more details on the browser login flow, see CLI login.

Step 1: Create ~/.codex/config.toml:

model_provider = "nanogpt"
model = "openai/gpt-6.1-sol"

[model_providers.nanogpt]
name = "NanoGPT"
base_url = "https://nano-gpt.com/api/v1"
env_key = "NANOGPT_API_KEY"
wire_api = "responses"

Recent Codex CLI versions require wire_api = "responses". Older examples that use wire_api = "chat" will fail on current Codex CLI releases.This manual configuration uses the website host for the recommended model. For long-running sessions with large payloads, use https://api.nano-gpt.com/api/v1 and choose a model from that host’s catalog. The installer keeps the direct host and chooses the newest recommended Sol model permitted by your API key, or another permitted model with tool support. If no permitted model supports tools, setup stops and asks you to update the key’s model access. It preserves an existing model selection.Step 2: Set your API key as an environment variable:macOS/Linux (add to ~/.zshrc or ~/.bashrc):

export NANOGPT_API_KEY="your_nanogpt_api_key"

Windows Cmd:

setx NANOGPT_API_KEY your_nanogpt_api_key

Windows PowerShell:

[System.Environment]::SetEnvironmentVariable('NANOGPT_API_KEY', 'your_nanogpt_api_key', 'User')

Replace your_nanogpt_api_key with your actual API key. Open a new terminal for changes to take effect.

If you just want to override the default OpenAI endpoint without a config file:

export OPENAI_BASE_URL="https://nano-gpt.com/api/v1"
export OPENAI_API_KEY="your_nanogpt_api_key"

This method works but does not persist across terminal sessions unless added to your shell profile.

Step 3: Start Using Codex

Once configured, start Codex in your terminal:

codex

Or explicitly use the current recommendation on the website host for one run:

codex --model openai/gpt-6.1-sol --config 'model_providers.nanogpt.base_url="https://nano-gpt.com/api/v1"'

After one-click setup, plain codex uses the model selected from the direct host’s catalog. For larger requests, keep that host and select a model it lists; the website override above has a smaller ingress limit.

FAQ

What Models Can I Use?

NanoGPT supports 400+ models. These recommendations use the manual website configuration above. One-click setup uses the direct host, whose model catalog can differ during a rollout.

Use Case	Recommended Model	Config
Best overall	`openai/gpt-6.1-sol`	`model = "openai/gpt-6.1-sol"`
Best Claude	`anthropic/claude-opus-5.5`	`model = "anthropic/claude-opus-5.5"`
Fast/cheap	`google/gemini-flash-latest`	`model = "google/gemini-flash-latest"`
Long context	`google/gemini-pro-latest`	`model = "google/gemini-pro-latest"`
Open model	`z-ai/glm-latest`	`model = "z-ai/glm-latest"`

List available models with GET https://nano-gpt.com/api/v1/models for the website configuration, or GET https://api.nano-gpt.com/api/v1/models for one-click setup’s direct host.

How Do I Change Models?

Option 1: Edit ~/.codex/config.toml:

model = "openai/gpt-6.1-sol"

For this recommendation, also set base_url = "https://nano-gpt.com/api/v1" in the existing [model_providers.nanogpt] section. To retain the direct host, choose a model from its catalog instead. Option 2: Use CLI flag:

codex --model openai/gpt-6.1-sol --config 'model_providers.nanogpt.base_url="https://nano-gpt.com/api/v1"'

Configuration Not Working?

Check your API key: Ensure NANOGPT_API_KEY is set
echo $NANOGPT_API_KEY
Verify config file: Check ~/.codex/config.toml exists and has valid TOML syntax
Open a new terminal: Environment variable changes require a new shell session
Reset configuration: Delete ~/.codex/config.toml and run the setup script again

How Is This Different From Using OpenAI Directly?

Feature	OpenAI Direct	NanoGPT
Pricing	Monthly subscription or API credits	Pay-as-you-go, no minimums
Models	OpenAI only	OpenAI + Claude + 400 other models
Billing	Separate OpenAI account	Single NanoGPT balance
Rate limits	OpenAI limits	NanoGPT limits

Can I Use Both Claude Code and Codex?

Yes. Both can be configured to use NanoGPT simultaneously:

Claude Code: Uses ~/.claude/settings.json with Anthropic API format
Codex CLI: Uses ~/.codex/config.toml with OpenAI API format

Both tools share the same NanoGPT credit balance.

Need Help?

Check your balance at nano-gpt.com/balance
View API usage at nano-gpt.com/usage
Create or manage API keys at nano-gpt.com/api
Contact support via the chat widget on nano-gpt.com

Get Started

Endpoint Examples

API Reference

Miscellaneous

Partner

Integrations

Codex CLI

Codex CLI

Step 1: Install Codex CLI

Step 2: Configure NanoGPT

Step 3: Start Using Codex

FAQ

What Models Can I Use?

How Do I Change Models?

Configuration Not Working?

How Is This Different From Using OpenAI Directly?

Can I Use Both Claude Code and Codex?

Need Help?

​Codex CLI

​Step 1: Install Codex CLI

​Step 2: Configure NanoGPT

​Step 3: Start Using Codex

​FAQ

​What Models Can I Use?

​How Do I Change Models?

​Configuration Not Working?

​How Is This Different From Using OpenAI Directly?

​Can I Use Both Claude Code and Codex?

​Need Help?

Codex CLI

Step 1: Install Codex CLI

Step 2: Configure NanoGPT

Step 3: Start Using Codex

FAQ

What Models Can I Use?

How Do I Change Models?

Configuration Not Working?

How Is This Different From Using OpenAI Directly?

Can I Use Both Claude Code and Codex?

Need Help?