350 Animated Themes & Dark Modes for ChatGPT, Claude & Gemini: Vellum

350 hand-built animated backgrounds for ChatGPT, Claude and Gemini, from pure black to neon cities. Free trial, no tracking.

Vellum turns ChatGPT, Claude and Gemini into something worth looking at. Most theme extensions just recolour the page. Vellum gives you 350 hand-built ANIMATED backgrounds, starfields that drift, koi gliding under lily pads, a night train through the mountains, a ramen cart in the rain, a chess game playing itself under a lamp, a humpback whale gliding through deep water, a camel caravan crossing the dunes by moonlight. They move. Quietly, in the background, while you work. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ FINDING ONE YOU LIKE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Three hundred and fifty is too many to scroll, so the collection is grouped into thirteen categories. Some are for working against and barely move; others are there because they are worth looking at. Pick a mood and browse that instead of the whole library. Search does the rest. Type a name, or type what you actually mean — "japan", "oled" and "rain" each find the right handful. Star the ones you keep coming back to and they sit at the top next time. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ BUILT FOR LONG SESSIONS ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Every scene is made to sit behind text for hours: slow, soft, and nothing that jumps or piles up. The brightest themes are capped behind your messages so reading stays easy, and every loop is seamless, so a theme left running all day never resets or stutters. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ SET THE PACE ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Every animated theme has a speed dial, from 10% to 100%. Turn a busy one down until it barely drifts, or leave it running at full. The slowdown happens inside the animation rather than by dropping frames, so a theme at 15% still draws every frame — no judder, no ghosting. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ OR BRING YOUR OWN ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Set any picture as your background and Vellum reads a palette out of it, so the sidebar, composer and text settle around your image instead of fighting it. Tune the drift and the opacity to taste. It is stored on your own machine and never uploaded. (Pro) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ WHY VELLUM ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ✓ Genuinely animated — not static gradients ✓ Simulated, not looped video — hand-written canvas, sharp at any window size ✓ Works on ChatGPT and Claude, and on Gemini with one click ✓ 20 free themes, forever — 10 of them animated — no account needed ✓ Search and favourites, so 350 stays browsable ✓ Pause and dim the background with Alt+Shift+V when you need to focus ✓ 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. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ONE THING FIRST ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Vellum is built for dark mode. Switch appearance to Dark in ChatGPT, Claude or Gemini's own settings before you pick a theme — in light mode they look washed out. To use Vellum on Gemini, open gemini.google.com and press Enable in the Vellum popup (or turn it on under Sites in the options page). Chrome asks for access to that one site only. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ FREE vs PRO ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Twenty themes are free forever — no card, no sign-up. Ten refined dark modes, from near-black through warm browns to deep greens, plus ten animated ones: aurora, koi, rain, fireflies, snowfall, bokeh, a lantern, a meadow, a café and a lighthouse. Pro unlocks all 350 — every animated background, the speed dial, your own image as a background, and new themes as they drop. £6.99 once, or £3.99 a year. Try the whole collection free for 7 days first. New device or reinstalled? "Restore purchase" opens the payment portal: sign in with your purchase email and it shows your licence key — no Vellum account needed. For teams, a company code applies your own colours and logo across everyone's install. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ PRIVACY ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Vellum collects nothing. No browsing history, no chat contents, no analytics, no account. It does not read what you type — it draws a background behind it. Your themes are stored in your own browser and sync via your Google account. Vellum keeps a local flag in your browser recording when your trial began, so that reinstalling does not hand out a second one; it is never transmitted. An image you set as your background stays on that device. The extension loads nothing from anyone else's server — no fonts, no CDNs, no scripts. The only network requests it ever makes are to validate a Pro licence key, and to fetch your company's theme if you enter a company code. Permissions, all of them used: storage (remember your theme), activeTab (the screenshot button), alarms (re-check a licence every 12 hours), scripting (run Vellum on Gemini once you allow it). Access to Gemini is optional and only requested when you turn it on. Vellum is an independent extension and is not affiliated with, endorsed by, or sponsored by OpenAI, Anthropic or Google.