Definition
The Job Declaration Protocol (JDP) is the Stratum V2 sub-protocol that hands block-template construction back to the miner. Under legacy mining protocols, the pool builds every block template and the miner simply hashes whatever it is given. JDP inverts that relationship: a miner can assemble its own list of transactions, declare that template to the pool, and then mine it while still receiving pooled payouts.
How declaration works
A miner running the Job Declarator Client builds a candidate template, typically sourced from its own Bitcoin node, and submits the declaration to a Job Declarator Server operated by or alongside the pool. The server validates the template's coinbase and transaction set, then authorizes the miner to hash it. Shares found against that self-declared job are credited normally, so the miner keeps the pool's variance-smoothing benefits while choosing its own transactions.
Decentralizing block construction
Transaction selection is one of the most under-appreciated forms of power in Bitcoin. When a few large pools select transactions for the majority of hashrate, they become potential chokepoints for censorship. JDP spreads that decision across every participating miner, making coordinated transaction filtering far harder to enforce. It pairs naturally with the Template Distribution Protocol, which supplies the raw templates from a local node.
JDP is one pillar of the broader Stratum V2 upgrade; the templates it declares are typically delivered by the Template Distribution Protocol.
In Simple Terms
The Job Declaration Protocol (JDP) is the Stratum V2 sub-protocol that hands block-template construction back to the miner. Under legacy mining protocols, the pool builds…