Stratum V2

💡 The Plain-English Definition

Stratum V2 is the next-generation mining communication protocol that fundamentally shifts transaction selection power from mining pool operators back to individual miners — while also adding encryption, reducing bandwidth, and dramatically lowering latency. As of 2026, it covers approximately 15–20% of Bitcoin’s total hash rate.

🤔 But Why Though?

The original Stratum protocol’s centralisation problem — pool operators controlling which transactions get confirmed — is addressed directly by Stratum V2’s Job Negotiation Protocol (JNP). Under JNP, individual miners run their own Bitcoin full node (a computer independently validating the blockchain), build their own block templates including whichever transactions they choose from the mempool, and submit those templates to the pool for approval. The pool verifies the block is valid and correctly pays the pool’s reward address, then approves the miner’s template. The miner hashes their own chosen transactions — pool operators no longer dictate content.

Beyond decentralisation, Stratum V2 delivers significant technical improvements. It uses binary message encoding instead of text-based JSON-RPC (the format Stratum used), reducing message size by up to 70% and cutting the time to switch to a new mining job from approximately 325 milliseconds to 1.4 milliseconds. This latency improvement meaningfully reduces wasted work from stale shares — computations performed on an already-outdated block template. All communications are encrypted using the Noise Protocol Framework (the same encryption technology used by the Signal messaging app and the Lightning Network), preventing hashrate hijacking — where attackers intercept miner communications and redirect their computational effort. The adoption timeline has been progressive. Braiins Pool (formerly Slush Pool) was the first full implementation. Demand Pool (DMND), launched in early 2025, was the first pool built exclusively on Stratum V2. Bitcoin Core 30.0, released October 2025, added an IPC (inter-process communication) interface enabling external software to connect to Bitcoin Core for block template fetching — a critical integration that simplifies Stratum V2 deployment alongside a full node.

🌍 The Real-World Analogy

Under the old Stratum protocol, pool operators are like restaurant owners who tell their chefs exactly what dishes to cook. The chefs have skills but no menu input. Under Stratum V2, each chef can propose their own menu to the owner, who approves it as long as the revenue targets are met. The owner still runs the business, but the choice of what to cook shifts from the owner to the person doing the cooking.