13.9k stars · MPL-2.0 · 0.33.4 (2026-08-24) · Track this in Scout
Turns HTML/CSS into images — mass-produce thumbnail variants and blog OG images from one template.
▶Repo detailsthe review · specs · pros & cons
What it is
A library that renders a subset of HTML and CSS into an image. It's the engine behind Vercel's automatic social-preview images, and it takes milliseconds per render with no design software involved.
What it is good for. Thumbnail click-through is the highest-leverage variable on YouTube, and hand-editing variants is exactly the chore that stops people testing. Define the layout once and generating an English version, a Russian version and six headline variants becomes a loop rather than an afternoon. The same template then produces the OG images for blog posts, so a site and a channel look like one brand instead of two.
- Bilingual variants are a one-line change — Cyrillic renders fine with the right font file
- No API cost, no GPU, no subscription
- Doubles as the blog's OG-image generator, unifying your visual identity
- It's a rendering primitive, not an app — you need a small wrapper around it
- Only a subset of CSS; complex flex/grid and filters silently differ
- Does nothing for the actual A/B test — that still happens in YouTube Studio
The same template then produces the OG images for your blog posts, so the site and the channel finally look like one brand instead of two.
