Cardano's Leios Testnet Launches June 23. Here Is What It Means for Scalability.
The Leios public testnet is scheduled to launch on June 23, 2026, marking a major milestone in one of Cardano's most ambitious scaling efforts to date.
What is Leios
Leios is a base-layer upgrade designed to significantly increase Cardano's transaction throughput. Rather than replacing Ouroboros Praos, the network's existing consensus protocol, Leios builds on top of it by introducing Endorser Blocks and committee-based validation.
The target is a 10 to 65x increase in throughput, with the long-term goal of pushing Cardano toward 1,000+ transactions per second — up from the current range of roughly 10-20 TPS.
Development progress
The CIP-164 specification has already been merged, and developers have demonstrated initial throughput results using an alpha, feature-complete implementation on a dedicated public test environment ahead of the June 23 launch.
The Leios proposal passed governance with 84% support from delegated representatives (DReps) as part of Input Output's 2026 treasury funding round. The $71 million in funding ensures continued development beyond the current budget cycle.
What comes next
The June testnet is the first real-world benchmark for Leios - the moment the upgrade shifts from simulation to live performance testing. The 2026/2027 development cycle will focus on maturing Leios from prototype to mainnet-ready, progressing through Software Readiness Levels 5 to 8.
Mainnet deployment is targeted for late 2026, pending successful testnet validation.
Why it matters
Leios is central to Cardano's 2030 scalability vision — a roadmap that aims to grow network capacity from roughly 800,000 monthly transactions to over 27 million. Alongside Hydra Layer 2 development, Leios represents one of the largest engineering investments in Cardano's history.
The June 23 testnet will provide the first concrete data on whether the parallel processing architecture can deliver meaningful throughput gains in practice — a key question for Cardano's long-term competitiveness.
