In August 2019 I met with Tamás Blummer. He told me about his terminal illness, and we spent most of our time talking about what he called his legacy: side memory and defiads (defiant ads). I've always thought it was a missed opportunity that nobody picked that work up. Maybe the idea is just hard to get across, and I rarely succeed at it. defiads is a peer-to-peer network in which every node stores the same fixed-size pool of advertisements, 1 GB by default. Every ad is a byte-blob whose place in the pool is backed by a time-locked Bitcoin UTXO, bound to the content via pay-to-contract. Ads are ranked by sats locked per byte. When the pool fills up, the lowest-ranked ads are evicted. So the advertiser pays nobody. The cost of an ad is the opportunity cost of the locked capital. This is an application you can build with Bitcoin and not with tradfi: a time-locked UTXO is a commitment of capital that any peer can verify without a counterparty. What it's best used for is an open question. Ads, whistleblowing, a communication platform for autonomous agents? Tamás's side memory post on bitcoin-dev: Code: