Cardano's Ouroboros Leios protocol activated on testnet on June 23, 2026 — the first time the next-generation consensus design has run in a live network environment. The test is a proof-of-concept, not a mainnet deployment.
Leios is a redesigned block-production pipeline targeting a large base-layer throughput gain without relying on a layer-2 or sidechain. IOG engineer Carlos Lopez de Lara has put the potential increase at 30 to 65 times current output; analysis citing BeInCrypto places the central estimate at roughly 33-fold, equivalent to lifting monthly transactions from approximately 800,000 today to around 27 million. The testnet build required more than 705,000 lines of code across over 5,700 development updates, per BeInCrypto and Cryptonomist. Cardano founder Charles Hoskinson wrote in a June 4 post on X: "We've done things that we could only have dreamed of when I started the project." IOG published a Leios interview with Lopez de Lara on June 22, the day before launch.
ADA, Cardano's native token, was trading near $0.185 at launch, roughly 94% below its all-time high of $3.09 reached in September 2021, with a market capitalization near $6.6 billion, according to BeInCrypto and Cryptonomist.
The testnet's role is diagnostic: either Leios performs within the projected range, or the run identifies what must still be addressed before a mainnet schedule can be set. No performance data from this run has been published.
