Deep Dive
1. V4 Architecture with ZK Proofs (July 2025)
Overview: This major upgrade overhauled Across's settlement layer to use zero-knowledge proofs (ZKPs), allowing it to securely connect to blockchains that weren't previously compatible, like Solana and BNB Smart Chain. For users, this means faster, cheaper bridging to a much wider variety of networks.
The new system uses ZKPs to create a universal verification pipeline. After relayers fulfill orders, the transaction data is anchored on Ethereum. A service then generates a cryptographic proof that this data is valid and final. This proof can be trustlessly verified on any destination chain, eliminating the need for custom, chain-specific adapter contracts. This reduces integration overhead and centralization risk while reinforcing Ethereum as the root of trust.
What this means: This is bullish for ACX because it significantly expands the protocol's potential user base and transaction volume by unlocking major new ecosystems. It makes bridging faster and more secure across virtually any blockchain, strengthening Across's competitive position as a leading cross-chain solution.
(Across)
2. Non-EVM and Prefill Support Upgrade (Jan 2025)
Overview: This earlier proposal laid the groundwork for supporting non-EVM chains and "prefill" transactions, where users receive funds instantly. It required breaking changes to smart contracts, meaning apps built on Across needed to update their integrations.
The upgrade involved renaming core contract events and methods (like FilledV3Relay to FilledRelay) and changing how deposit IDs work. The most significant shift was removing the assumption that fills always happen after deposits, which is essential for enabling instant prefill user experiences. This required all third-party integrators to update their code to maintain compatibility.
What this means: This was a neutral but necessary step for ACX's long-term growth. While it created short-term work for partners, it enabled the protocol to pursue faster user experiences and expand into new, fast-growing blockchain networks beyond Ethereum and its Layer 2s.
(Across Protocol Forum)
Conclusion
Across Protocol's development trajectory is firmly focused on chain abstraction, using advanced cryptography like ZK proofs to become a ubiquitous, secure settlement layer for all blockchains. How will adoption on newly supported chains like Solana and Monad translate into protocol usage and demand for its underlying infrastructure?