Introduction

Ogre is a pure Go alternative to Vercel’s Satori for converting HTML and CSS into SVG, PNG, and JPEG images. It is designed for generating OpenGraph images, social cards, and dynamic image content from templates.

What is this for?

When you share a link on Twitter, Slack, Discord, or LinkedIn, a preview image appears. That image is an OpenGraph (OG) image. Instead of designing a static image for every page, you can generate them from an HTML template.

Ogre handles this. Write HTML with inline styles or Tailwind classes, pass it to Ogre, get an image back. Use it as a Go library, a standalone CLI, or a self-hosted HTTP server. Blog post cards, documentation pages, event banners, repo cards, or any dynamic image your application needs.

go install github.com/macawls/ogre/cmd/ogre@latest

Quick look

result, _ := ogre.Render(`
    <div class="flex w-full h-full bg-slate-900 p-16 items-center justify-center">
        <div class="text-5xl font-bold text-white">Hello World</div>
    </div>
`, ogre.Options{Width: 1200, Height: 630})

os.WriteFile("og.svg", result.Data, 0644)

Why this exists

Dynamic image generation (OG cards, social previews, certificates, invoices) typically involves one of these:

• Satori requires a JavaScript runtime. For non-JavaScript backends, that means a separate service.
• Headless Chrome / Puppeteer uses hundreds of megabytes of RAM and takes seconds per render.
• Image manipulation libraries (like Go’s image package) work but require manual layout instead of HTML/CSS.

Ogre compiles to a single static binary with CGO_ENABLED=0. Add it as a dependency and call ogre.Render(), or run it as a standalone HTTP server.

	Ogre	Satori
Binary	11 MB static binary	JavaScript runtime required
Simple render	0.03–0.08 ms	0.3–2.5 ms
Complex render	3–8 ms	4–17 ms
Output	SVG, PNG, JPEG	SVG only
Use as library	go get, one function	npm package

Render times measured on AMD Ryzen 5 5600H, 1200x630 renders, both producing SVG. Full benchmark data in Satori Comparison.

Design goals

• Pure Go. No CGo, no external binaries. Single static binary with CGO_ENABLED=0.
• Output quality first. The priority is correct, complete rendering — PNG/JPEG output, inline SVGs, box shadows, CSS filters, transforms, RTL text. Performance optimizations follow once output fidelity is solid.
• Tailwind built-in. Resolves Tailwind v3 utility classes directly. No build step needed.
• Production-ready server. Includes an HTTP server with LRU caching, rate limiting, and template support.

Dependencies

Standard library, golang.org/x/*, and one external package:

• golang.org/x/net/html for HTML parsing
• golang.org/x/image/font for font interfaces and rasterization
• golang.org/x/image/vector for 2D vector path rasterization
• golang.org/x/text/unicode/bidi for bidirectional text
• github.com/go-text/typesetting for text shaping (kerning, ligatures, RTL)

Output formats

Format	Content Type	Notes
SVG	image/svg+xml	Font glyphs embedded as path data. Self-contained.
PNG	image/png	Rasterized with gradient support.
JPEG	image/jpeg	Configurable quality (default 90).