First screen, captured 10 hours ago. Open the video.

Reverse engineering my Coway air purifier to ditch the cloud

What HN thinks

Everyone agrees the fan should not need the internet; they disagree only on how many protocols, LLMs and furnace filters it takes to get there.

Cheers for de-clouding devices
Many applaud freeing hardware from vendor clouds and prefer buying local-protocol gear like Zigbee or Z-Wave with Home Assistant instead of rewarding lock-in.
LLMs make reverse engineering accessible
Commenters note AI tools speed through the tedious parts of reverse engineering, exposing sloppy choices like fetching a root CA over plain HTTP, though some worry AI vendors will start refusing such work.
Skepticism of smart devices and Matter
Some question why an air purifier needs a cloud at all, and others criticise Matter for certification fees and easy internet phoning-home.

Consensus: Most agree that devices should work locally without vendor clouds and that the cloud dependency here was poorly designed and insecure.

Recommended in the comments

Home Assistant (tool): Recommended as the free, local hub for integrating devices without cloud dependence.
Zigbee (other): Praised as a local-only, private, inexpensive protocol.
Z-Wave (other): Praised alongside Zigbee as local-only and private.
Corsi-Rosenthal Box ↗ (other): Suggested as a cheap, effective alternative to commercial air purifiers.
Coway (product): Called among the best purifiers, with many non-connected models available.

Summarised by Claude from the comment thread 9 hours ago.

Points: 667
Comments: 198
Best rank: #1
Posted: 2026-11-12 by scottjg
Category: Hardware

reverse-engineering iot coway home-assistant mitmproxy raspberry-pi tls-certificates

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