Nanobanana

A lightweight CLI tool for generating and editing images using Google's Gemini API or OpenRouter.

Best used with your coding agent CLI of choice! This tool pairs excellently with Claude Code and similar AI coding assistants for automated image generation workflows.

Features

• Text-to-image generation - Create images from text prompts
• Image editing - Transform existing images with text instructions
• Multi-image composition - Combine multiple input images
• Flexible output - 10 aspect ratios and 3 size options
• Multiple API backends - Use Gemini API directly or via OpenRouter

Requirements

• Python 3.14+
• Google Gemini API key OR OpenRouter API key

Installation

Via uv (recommended)

uv tool install nanobanana-cli
nanobanana install-skill

The first command installs the CLI. The second installs the Claude Code skill to ~/.claude/skills/nanobanana/.

Via pip

pip install nanobanana-cli
nanobanana install-skill

From source

git clone https://github.com/sussdorff/nanobanana.git
cd nanobanana
./install.sh

install.sh does both steps in one go (CLI + skill).

Setup

Option 1: Gemini API (Direct)

1. Get a Gemini API key from Google AI Studio
2. Set it as an environment variable:

export GEMINI_API_KEY="your-api-key-here"

Option 2: OpenRouter

1. Get an API key from OpenRouter
2. Set it as an environment variable:

export OPENROUTER_API_KEY="your-api-key-here"

Configuration

Config File (Recommended)

Create a config file at ~/.config/nanobanana/config.json:

{
  "api": "openrouter",
  "model": "google/gemini-3-pro-image-preview",
  "aspect": "16:9",
  "size": "2K"
}

Field	Description	Values
api	API backend	gemini or openrouter
model	OpenRouter model	e.g., google/gemini-3-pro-image-preview
aspect	Default aspect ratio	1:1, 16:9, etc.
size	Default image size	1K, 2K, 4K

The config file location follows the XDG spec: $XDG_CONFIG_HOME/nanobanana/config.json

Priority

Settings are resolved in this order (highest to lowest):

1. CLI flags
2. Config file
3. Environment variables (API keys only)
4. Built-in defaults

Shell Wrapper Example

For 1Password users, a simple wrapper in .zshrc:

nanobanana() {
  if [[ -z "$OPENROUTER_API_KEY" ]]; then
    export OPENROUTER_API_KEY="$(op read 'op://API Keys/OpenRouter/credential')"
  fi
  command nanobanana "$@"
}

Usage

nanobanana <command> [options] "prompt"
nanobanana [options] "prompt"            # defaults to free-form generation

Commands

Each command wraps your prompt in an optimized template with sensible defaults.

Design Exploration:

Command	Description	Default Aspect	Default Size
dashboard	KPI/analytics dashboard mockup	16:9	2K
moodboard	Website/app moodboard collage	1:1	2K
explore	Same concept in 4 style variations	1:1	2K
wireframe	UI wireframe or screen layout	16:9	2K

Content Creation:

Command	Description	Default Aspect	Default Size
slide	Presentation slide	16:9	2K
social	Social media post image	1:1	2K
icon	App icon	1:1	1K
architecture	System/cloud architecture diagram	16:9	2K

Base:

Command	Description
generate	Free-form prompt (explicit version of default)
help	Show help for all commands or a specific command
version	Show version

If the first argument is not a known command, it is treated as a free-form prompt (backwards compatible).

Options

Flag	Description	Default
-i <file>	Input image (repeatable for multiple images)	none
-o <file>	Output filename	image_YYYYMMDD_HHMMSS.png
-aspect <ratio>	Aspect ratio (overrides command default)	1:1
-size <size>	Image size (overrides command default)	1K
-model <model>	OpenRouter model (enables OpenRouter API)	google/gemini-3-pro-image-preview
-h	Show help	-
-version	Show version	-

Supported Aspect Ratios

1:1, 2:3, 3:2, 3:4, 4:3, 4:5, 5:4, 9:16, 16:9, 21:9

Supported Sizes

Size	Resolution
1K	~1024px
2K	~2048px
4K	~4096px

Supported Image Formats

PNG, JPEG, WebP, GIF

Examples

Subcommands

# Dashboard mockup (16:9, 2K by default)
nanobanana dashboard "SaaS metrics with MRR, churn rate, and user growth"

# Presentation slide
nanobanana slide "Q4 revenue highlights: 40% YoY growth, 3 new enterprise clients"

# App icon
nanobanana icon "podcast app with microphone and sound waves"

# Architecture diagram
nanobanana architecture "microservices with API gateway, 3 services, Redis cache, PostgreSQL"

# Design exploration (4 style variations)
nanobanana explore "landing page hero for a meditation app"

# Moodboard
nanobanana moodboard "fintech app targeting young professionals"

# Wireframe
nanobanana wireframe "settings page with account, notifications, and billing"

# Social media post
nanobanana social "product launch announcement for an AI writing tool"

# Override command defaults
nanobanana dashboard -size 4K "quarterly revenue breakdown"
nanobanana social -aspect 9:16 "instagram story for product launch"

# Get help for a specific command
nanobanana help dashboard

Free-form generation

# Simple generation (no command = free-form)
nanobanana "a cute cat sitting on a windowsill"

# With aspect ratio and size
nanobanana -aspect 16:9 -size 2K "cinematic mountain landscape at sunset"

# Custom output filename
nanobanana -o hero-image.png "abstract geometric pattern"

Using OpenRouter

# Use default model (gemini-3-pro-image-preview)
nanobanana -model google/gemini-3-pro-image-preview "a cute cat"

# Use a different model
nanobanana -model google/gemini-2.5-flash-image-preview "a sunset over mountains"

Image editing

# Style transfer
nanobanana -i photo.jpg "transform into watercolor painting"

# Modifications
nanobanana -i portrait.png "add sunglasses"

Multi-image composition

# Combine images
nanobanana -i background.png -i subject.png "place the subject in the scene"

# Style reference
nanobanana -i content.jpg -i style.jpg "apply the style to the content image"

Examples Directory

The examples/ folder contains working examples with generated images:

basic/

Simple text-to-image generation.

nanobanana -o basic_example.png "a friendly yellow banana character"

presentation/

Generate presentation slides from text prompts.

nanobanana -aspect 16:9 -size 2K -o slide_01.png "title slide prompt..."
nanobanana -aspect 16:9 -size 2K -o slide_02.png "content slide prompt..."

branded-presentation/

Use a template image as a style reference for consistent branding across slides.

# 1. Generate a style template first
nanobanana -aspect 16:9 -size 2K -o template.png "slide template with brand colors..."

# 2. Generate slides using template as reference
nanobanana -i template.png -aspect 16:9 -size 2K -o slide_01.png "title slide..."
nanobanana -i template.png -aspect 16:9 -size 2K -o slide_02.png "content slide..."

Each example includes a README and the markdown source used to generate the images. See the examples/ folder for full prompts and generated outputs.

Using with Coding Agents

Nanobanana works great with AI coding assistants like Claude Code for automated image generation workflows:

1. Describe slides/images in a markdown file
2. Your coding agent reads the markdown and extracts prompts
3. The agent runs nanobanana to generate each image

See examples/branded-presentation/ for a complete workflow demonstration.

API Pricing

Gemini API (Direct)

Uses gemini-3-pro-image-preview model. Approximate costs:

Size	Cost per Image
1K-2K	~$0.13
4K	~$0.24

See Gemini API Pricing for current rates.

OpenRouter

Pricing varies by model. See OpenRouter Pricing for current rates.

Development

# Run tests
uv run pytest -v

# Run the CLI locally
uv run nanobanana -version
uv run nanobanana -h

License

MIT