220 Animated Themes & Dark Modes for ChatGPT and Claude: Vellum

Transform ChatGPT and Claude with 220 hand-built animated backgrounds, from pure black to neon cities. Free trial, no tracking.

Vellum turns ChatGPT and Claude into something worth looking at. Most theme extensions just recolour the page. Vellum gives you 220 hand-crafted ANIMATED backgrounds — starfields that drift, koi gliding under lily pads, a black hole pulling matter into its accretion disk, neon grids racing to the horizon, and a whole arcade of playable-looking classics. They move. Quietly, in the background, while you work. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 220 THEMES, ORGANISED ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Browse by category instead of endless scrolling: ★ Retro — 35 ★ Nature — 21 ★ Space — 21 ★ Abstract — 20 ★ Minimal — 19 ★ City — 17 ★ Weather — 16 ★ Ambient — 15 ★ Cyber — 12 ★ Fire — 12 ★ Seasonal — 12 ★ Geometric — 12 ★ Audio — 8 Search any theme by name, and star the ones you keep coming back to. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ WHY VELLUM ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✓ Genuinely animated — not static gradients ✓ Simulated, not looped — the metronome's tempo follows the weight on its rod, a comet's tails stream away from the sun, fireflies fall into sync by nudging each other ✓ Hand-written canvas, not video — sharp at any window size, a fraction of the memory ✓ Works on both ChatGPT and Claude ✓ 31 free themes, forever, no account needed ✓ Search and favourites, so 220 stays browsable ✓ Syncs across your devices ✓ One-click screenshots of your themed chat ✓ Dark-mode native — tuned so text stays comfortable to read for hours ✓ No data collected. No tracking, no analytics, no accounts. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ FREE vs PRO ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 31 themes are free forever — no card, no sign-up. Pro unlocks all 220, including every animated background, plus new themes as they drop. Try everything free for 7 days. Cancel any time. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ PRIVACY ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Vellum collects nothing. No browsing history, no chat contents, no analytics, no account. Your themes are stored in your own browser and sync via your Google account. Vellum stores a local flag in your browser to track trial status; it is never transmitted. Vellum is an independent extension and is not affiliated with, endorsed by, or sponsored by OpenAI or Anthropic.