# Clever hacker fits 537,000 domains in a tiny $5 ESP32 ad-blocking dongle — firmware uses only around 50KB of RAM and can answer blocked lookups in 10 milliseconds

> How cheap can you build a hardware-based ad-blocking DNS filter? "Free," if you're willing to salvage some used hardware that's being thrown away. What if you aren't so lucky?

- **Source:** [Tom's Hardware](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?utm_source=gearopen.com&utm_medium=referral&utm_campaign=feed&utm_content=6a5cbfdef3afbb5cbffdc1a5)
- **Published:** 2026-07-19
- **Category:** Phones
- **Tags:** #blocking #answer #around #blocked #clever #domains #dongle #esp32
- **Canonical:** http://localhost:4321/a/6a5cbfdef3afbb5cbffdc1a5

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_GearOpen's distilled summary. The full original article is published at Tom's Hardware (source link above); GearOpen does not republish the source's full text._