ESP32-C3 Adblock

An ESP32-C3 microcontroller ($2) can function as a Pi-hole-style DNS ad-blocker by storing 140,000+ domain blocklist entries as 40-bit hashes in flash memory rather than keeping full domain strings in RAM, enabling ad-blocking with just 50 KB of RAM and no PSRAM required. The key innovation is using binary search on sorted hashes stored in flash (~0.7 MB) to match domains in approximately 10 milliseconds, which is more efficient than traditional approaches that load entire blocklists into memory.