Innovative Open-Source DNS Ad Blocker for ESP32-C3

A new open-source project called esp32-c3-adblock has emerged, designed by developer Zed (M-Abozaid). This innovative DNS ad blocker operates on the affordable $2 ESP32-C3 microcontroller, eliminating the need for PSRAM while effectively blocking ads and tracking domains on home and small office networks.

The system functions by filtering DNS requests, utilizing a unique method of storing domain information as sorted 40-bit FNV-1a hashes in flash memory. This allows the ESP32-C3 to manage over 140,000 domains within approximately 0.7 MB of flash storage, while only consuming around 50 KB of RAM. When a DNS query is received, the firmware hashes the domain and conducts a binary search against the stored hash table to determine if the domain is blocked. If it is, the device returns a 0.0.0.0 response to prevent the request from proceeding.

This efficient approach enables the ESP32-C3 to support a blocklist of over 500,000 domains, making it a powerful tool for users looking to enhance their online privacy without incurring high costs or requiring complex setups.

Source: CNX Software – Embedded Systems News (https://www.cnx-software.com/2026/10/09/open-source-esp32-c3-dns-ad-blocker-supports-up-to-over-500000-domains-without-psram/)