# Hacker crams 537,000 domains into $5 ESP32 ad-blocker

A developer loaded half a million blocking rules onto a cheap ESP32 microcontroller to create an offline ad-blocking dongle. The project showcases how low-cost hardware can effectively filter web ads without needing a computer or router. It matters because it makes ad-blocking more accessible and portable for privacy-conscious users.

**Importance:** 3/5

## Sources

### Technology
- [Hacker News](https://www.tomshardware.com/networking/clever-hacker-fits-537-000-domains-in-a-tiny-usd5-esp32-ad-blocking-dongle-firmware-uses-only-around-50kb-of-ram-and-can-answer-blocked-lookups-in-10-milliseconds) — Sun, 19 Jul 2026 14:07:07 +0000