--- title: This tiny ESP32 gadget blocks 537,000 domains while... description: Developer ZedAxis (M-Abozaid on GitHub) built a DNS-based ad blocker on a $5 ESP32-C3 SuperMini microcontroller that blocks 537,000 domains using only 50KB of... canonical: https://daily.dev/posts/this-tiny-esp32-gadget-blocks-537-000-domains-while-using-just-50kb-of-ram-miptesp4w twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: This tiny ESP32 gadget blocks 537,000 domains while using just 50KB of RAM | daily.dev og:description: Developer ZedAxis (M-Abozaid on GitHub) built a DNS-based ad blocker on a $5 ESP32-C3 SuperMini microcontroller that blocks 537,000 domains using only 50KB of... og:url: https://daily.dev/posts/this-tiny-esp32-gadget-blocks-537-000-domains-while-using-just-50kb-of-ram-miptesp4w og:image: https://api.daily.dev/og/posts/mIpteSp4w.png og:image:alt: This tiny ESP32 gadget blocks 537,000 domains while using just 50KB of RAM og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # This tiny ESP32 gadget blocks 537,000 domains while using just 50KB of RAM **[XDA Developers](https://daily.dev/sources/xda-developers)** · 2 min read · 0 upvotes · 0 comments ## Summary Developer ZedAxis (M-Abozaid on GitHub) built a DNS-based ad blocker on a $5 ESP32-C3 SuperMini microcontroller that blocks 537,000 domains using only 50KB of RAM. The trick: instead of loading a full blocklist into RAM like Pi-hole does, each domain is hashed to a maximum of 5 bytes (40 bits) and stored in flash memory, then binary-searched at query time — enabling 10ms response times. The project is fully open-source under the MIT license and includes a Python script to generate the hash table. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Open-source ESP32-C3 DNS ad blocker supports up to over 500,000 domains without PSRAM](https://daily.dev/posts/open-source-esp32-c3-dns-ad-blocker-supports-up-to-over-500-000-domains-without-psram-2tkzybbyz) · CNX Software · 0 upvotes · 0 comments - [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](https://daily.dev/posts/clever-hacker-fits-537-000-domains-in-a-tiny-5-esp32-ad-blocking-dongle-firmware-uses-only-around-4vxm5fukb) · Hacker News · 5 upvotes · 0 comments - [Your home network doesn't need Pi-hole — an $8 ESP32 blocks ads just as well for a fraction of the cost](https://daily.dev/posts/your-home-network-doesn-t-need-pi-hole-an-8-esp32-blocks-ads-just-as-well-for-a-fraction-of-the-c-zxf5m6v3g) · XDA Developers · 2 upvotes · 0 comments - [Ad-blocking doesn't need a Raspberry Pi — a $15 ESP32 handles it just fine](https://daily.dev/posts/ad-blocking-doesn-t-need-a-raspberry-pi-a-15-esp32-handles-it-just-fine-sztjnka8m) · XDA Developers · 0 upvotes · 0 comments - [Someone is running a website entirely off an ESP32 with 520 KB of RAM, and you can too](https://daily.dev/posts/someone-is-running-a-website-entirely-off-an-esp32-with-520-kb-of-ram-and-you-can-too-jkigjoyet) · XDA Developers · 0 upvotes · 0 comments --- Tags: [#iot](https://daily.dev/tags/iot), [#embedded](https://daily.dev/tags/embedded) [View this post on daily.dev](https://daily.dev/posts/this-tiny-esp32-gadget-blocks-537-000-domains-while-using-just-50kb-of-ram-miptesp4w) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"This tiny ESP32 gadget blocks 537,000 domains while using just 50KB of RAM","url":"https://daily.dev/posts/this-tiny-esp32-gadget-blocks-537-000-domains-while-using-just-50kb-of-ram-miptesp4w","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/this-tiny-esp32-gadget-blocks-537-000-domains-while-using-just-50kb-of-ram-miptesp4w"},"datePublished":"2026-07-20T17:19:20.563Z","dateModified":"2026-07-20T17:23:45.792Z","description":"Developer ZedAxis (M-Abozaid on GitHub) built a DNS-based ad blocker on a $5 ESP32-C3 SuperMini microcontroller that blocks 537,000 domains using only 50KB of...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/70280266845c95a7f5b9161ab3fdba4a?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/70280266845c95a7f5b9161ab3fdba4a?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"XDA Developers","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"XDA Developers","logo":"https://media.daily.dev/image/upload/s--kCg6yyAP--/f_auto,q_auto/v1774964407/logos/xda-developers?_a=BAMAMiWQ0","url":"https://daily.dev/sources/xda-developers"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/this-tiny-esp32-gadget-blocks-537-000-domains-while-using-just-50kb-of-ram-miptesp4w","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"iot,embedded","timeRequired":"PT2M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"XDA Developers","item":"https://daily.dev/sources/xda-developers"},{"@type":"ListItem","position":3,"name":"This tiny ESP32 gadget blocks 537,000 domains while using just 50KB of RAM"}]} ```