How I Built a WordPress Plugin for AI Image Generation in One Evening with Claude Code

TL;DR: Tired of wasting time finding illustrations for blog posts. Built a plugin that generates featured images with one click inside WordPress. Freepik gives you $5 credit on signup — enough for 100-250 images for free.

The Problem: Illustrations Eat Your Time

Anyone who runs a blog knows this pain: you write the post, proofread it, format it — then spend another 30 minutes searching for the right image.

My options before:

Stock photos — look the same on every website, boring
Canva — good, but extra steps: open, design, export, upload
DALL-E / Midjourney — great quality, but clunky workflow: generate separately, download, upload to WordPress
Manual design — best results, but unrealistic for every post

I wanted something simple: click a button in WordPress → image is generated and set as featured image.

The Solution: Custom Plugin + Freepik API

Why Freepik:

6 quality models — from HyperFlux (ultra-fast) to Flux 2 Pro (premium quality)
Output format choice — WebP, AVIF, JPEG, PNG
Simple API — clear documentation, logical endpoints
$5 free credit — Freepik gives you $5 on signup, enough for 100-250 generations
Fair pricing — from ~$0.02 per image

Building with Claude Code

I built the entire plugin in one evening using Claude Code. The process:

Described what I wanted: “WordPress plugin, metabox in editor, Generate button, Freepik API call, save as featured image”
Claude generated the basic structure
A few iterations to refine: settings page, model selection, category styles
Testing and fixes

Total time: ~4 hours from idea to working plugin.

What the Plugin Does

🎨 AI Model Selection

The plugin supports 6 models for any use case and budget:

Model	Best For	Quality	Speed
Mystic	Illustrations, flat design	Excellent	Medium
Flux Dev	General purpose	Good	Fast
Flux Pro 1.1	Maximum quality	Premium	Slow
Flux 2 Pro	Latest premium	Premium	Medium
Flux 2 Turbo	Fast premium	Premium	Fast
HyperFlux	Speed priority	Good	Ultra Fast

My picks: Mystic for blog illustrations, HyperFlux when I need something quick.

🖼️ Output Formats

Choose the image format that fits your needs:

Format	Best For	File Size
WebP	Modern browsers (recommended)	Small
AVIF	Latest browsers	Smallest
JPEG	Maximum compatibility	Medium
PNG	Transparency support	Large

Recommendation: WebP offers the best balance of quality and file size.

📐 Image Formats

1:1 — social media
4:3 — classic
2:1 — blog headers (recommended)
16:9 — video thumbnails
9:16 — stories

🎯 Smart Prompts

The plugin automatically builds prompts from:

Post title
Category
Excerpt (first 100 characters)
Configured style for the category

Example system prompt:

Create a professional blog header image for an article titled "{title}". 
Style: {style_description}. 
Include elements: {elements}. 
Mood: {mood}. 
Category: {category}.

🏷️ Category Styles

Configure unique visual styles for each blog category:

Category: "taxes"
Colors: "deep blue, gold accents, corporate feel"
Elements: "documents, calculator, charts"
Mood: "professional, trustworthy"

Now all posts in “Taxes” category will have a consistent visual style.

⚡ Auto-Generation

Optional: the plugin can automatically generate an image when a post is published if no featured image is set.

How It Looks

A metabox appears in the WordPress editor called “AI Image Generator”:

See a style preview based on post category
Click “Generate Image”
Wait 10-30 seconds
Image is automatically set as featured image

Don’t like the result? The “Regenerate” button creates a new variation.

Results

Several examples of the plugin’s performance on a finance website

1 / 7

appears in the WordPress editor called “AI Image Generator”:

See a style preview based on post category
Click “Generate Image”
Wait 10-30 seconds
Image is automatically set as featured image

Don’t like the result? The “Regenerate” button creates a new variation.

Installation & Setup

Step 1: Get Freepik API Key

Sign up at freepik.com/api
Bonus: Freepik credits you $5 on signup
Copy your API key from the dashboard

Step 2: Install the Plugin

# Option 1: Clone from GitHub
cd wp-content/plugins/
git clone https://github.com/nesmachny/freepik-featured-image-generator.git

# Option 2: Download ZIP and upload via WordPress admin

Step 3: Configure

Activate the plugin in WordPress
Go to Settings → AI Image Generator
Paste your API key
Choose default model
Configure category styles (optional)

Economics: What Does It Cost?

Starting balance: $5 (free on signup)

Cost per generation (approximate):

HyperFlux: ~$0.02 (cheapest)
Flux Dev: ~$0.03
Mystic: ~$0.04
Flux 2 Turbo: ~$0.05
Flux 2 Pro: ~$0.06
Flux Pro 1.1: ~$0.08

$5 gets you:

~250 images with HyperFlux
~160 images with Flux Dev
~100 images with Mystic
~60 images with Flux Pro 1.1

For a small blog (2-4 posts per week), the free $5 lasts 6-12 months. After that — pennies per post.

REST API for Automation

The plugin provides REST API for integrations:

# Generate image for a post
POST /wp-json/aifig/v1/generate/{post_id}

# Custom prompt
POST /wp-json/aifig/v1/custom
{
  "prompt": "Futuristic cityscape with flying cars",
  "post_id": 123
}

Connect to n8n, Zapier, or your own scripts.

Tips for Better Results

Works well:

Abstract concepts
Illustrations and flat design (Mystic model)
Landscapes and architecture
Technology imagery

Works less well:

Text in images (often garbled)
Specific human faces
Highly detailed diagrams

Pro tip: Anti-text

In the latest version (v1.1.1), I added automatic “no text, no letters, no words” instruction to prompts — this significantly improved results.

Summary

Problem: Spending 30+ minutes finding illustrations for each post

Solution: WordPress plugin + Freepik API + Claude Code

Result:

Generation in 10-30 seconds
6 AI models + 4 output formats (WebP/AVIF/JPEG/PNG)
Consistent style per category
$5 free to start (100-250 images)
Full control via settings