Introduction

A .NET CLI tool for generating blog and YouTube thumbnail images from HTML templates.

What is ImgForge?

ImgForge is a command-line tool that creates images from HTML templates with customizable text overlays. It’s perfect for:

Blog post Open Graph images — Social preview cards for sharing on Twitter, LinkedIn, Facebook
YouTube thumbnails — Eye-catching video preview images
Podcast artwork — Show and episode art
GitHub repository previews — Social preview cards for repositories

How It Works

ImgForge follows a three-stage pipeline:

Template rendering — An HTML template (built-in or custom) is loaded and variable placeholders are replaced with the supplied values (title, background, dimensions, overlays) using Scriban.
Browser rendering — The resulting HTML is loaded into a headless Chromium browser via PuppeteerSharp, which applies all CSS layout and styling exactly as a real browser would.
Screenshot capture — PuppeteerSharp screenshots the rendered page at the specified viewport size and writes a PNG to the output path.

GenerateOptions
      │
      ▼
TemplateRenderer  (Scriban: injects title, bg, width, height, overlays into HTML)
      │
      ▼
    HTML string
      │
      ▼
ImageGenerator    (PuppeteerSharp: loads HTML in headless Chromium, screenshots to PNG)
      │
      ▼
    output.png

Next Steps

Getting Started — Install and run your first command
Usage Guide — Learn all the available options
Templates — Understand built-in and custom templates