Artblock turns every ad you see on the internet into a masterpiece. Instead of banners, pop-ups, sponsored widgets, and "you may also like" clickbait, Artblock fills those slots with fine art, historical photography, and cosmic imagery from three of the world's great open-access collections:

Art Institute of Chicago — paintings, Japanese woodblock prints, photography (Monet, Hokusai, O'Keeffe, and thousands more)
The Metropolitan Museum of Art — centuries of painting, sculpture, and design
NASA Image Library — nebulae, galaxies, Earthrise, the Pillars of Creation, astronaut portraits

Features

Detects Google Ads, DoubleClick, Amazon ads, Taboola/Outbrain, MGID, RevContent, sponsored content blocks, affiliate widgets, and inline newsletter/paywall prompts — then replaces them with a piece of art sized to fit.
Pick a mood: Impressionism, Japanese Woodblock, Renaissance, Photography, Modern/Contemporary, NASA Space, or Chaos Mode (everything mixed).
Never shows you the same image twice in a session.
Hover any replaced ad to see the title, artist, date, and source museum.
Tracks how many ads it has replaced on the current page with a badge.

Privacy

No analytics, no telemetry, no accounts, no tracking.
No data leaves your browser except direct requests to the three public museum/NASA APIs to fetch art.
Works entirely client-side. Open-source: https://github.com/vuciv/artblock

The internet should be beautiful. Put it back.