I've been reading through the paper on the hydra protocol and seems to have a lot of nice properties. However, what isn't directly clear from the paper is in what kinds of dApps hydra could help scale.

There seems to me to be a couple of limits (please add/debate the list)

  • All head members must be online
  • A head member can force the head to be closed
  • resource heavy? Could I run a head on a mobile phone?

Let consider NFT-maker/pro as an example application. Could they use hydra to lower the NFT minting fees? The buyers of the NFTs are on the mainchain so setting up an entire head for one transaction isn't reasonable.

What kind of apps would hydra be able to scale?


1 Answer 1


Keep in mind that Hydra is a whole suite of protocols, some of which are still in the research phase.

On Hydra Head specifically, you can think of it as a protocol for creating and maintaining fully composable and dynamically available state machines between willing participants, with snapshots being periodically committed to the CSL.

Participants of the Hydra Head are analogous to SPOs; except they are tasked with maintaining consensus only on the state of the head. Depending on the size, scope, and function of each head, the consensus and ledger mechanics may greatly differ between some head protocols, but will nevertheless be settle-able on the main chain. Additionally, the Hydra Inter-head paper describes ways to create channels between heads without having to close them or pre-settle on the CSL.

Hydra Tail is an upcoming paper that, according to the having-read-about-it-long-ago whispers of my mind, describes how individual head participants can offer centralized services to individuals. (i.e. I, as a lone L2 state operator, can offer you and many others some sort of service on my machines). People with thin clients/mobile devices in remote regions would be able to transact through a single or small handful of trusted operators.

This would in effect, create the first fully interoperable stack of protocols across the ENTIRE length of the THROUGHPUT -------- DECENTRALIZATION spectrum. For the first time ever, we'd have a family of protocols that make the security of a decentralized settlement layer and the throughput of a centralized compute layer interoperable.

  • Ah, I see, I will have to do some further reading. :) Nov 26, 2021 at 17:50
  • Is there any paper (or other detailed description) available for the Hydra Tail protocol? Dec 1, 2021 at 9:01
  • Not yet. So far, papers have been publish about heads, and about cross-head communication.
    – KtorZ
    Dec 1, 2021 at 21:05

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