Classification: Optimistic Rollup. Arbitrum uses multi-round fraud proofs to verify state transitions off-chain while posting transaction data to Ethereum L1. The Nitro upgrade introduced WASM-based proof system, enabling near-EVM equivalence. Processes transactions in batches with a 7-day challenge window for dispute resolution. Current throughput exceeds 40,000 TPS theoretical maximum.
Classification: ZK-Rollup. zkSync Era employs zero-knowledge SNARK proofs to validate computation off-chain, posting only validity proofs to Ethereum. Native account abstraction enables smart contract wallets by default. The LLVM-based compiler supports Solidity and Vyper with zkEVM compatibility. Achieves finality in minutes rather than the 7-day optimistic window.
Classification: ZK-Rollup (STARK). StarkNet utilizes STARK proofs -- transparent, post-quantum secure validity proofs requiring no trusted setup. Programs are written in Cairo, a Turing-complete language designed for provable computation. The recursive proof system allows proof aggregation, dramatically reducing per-transaction verification costs on L1.
Classification: State Channel (Bitcoin). The Lightning Network creates bidirectional payment channels between participants, enabling instant micropayments without on-chain confirmation. Hash Time-Locked Contracts (HTLCs) enable multi-hop routing through intermediary nodes. Channel capacity is pre-funded, creating a mesh network of liquidity pathways across the Bitcoin base layer.
Classification: Sidechain / Commit Chain. Polygon operates as an EVM-compatible sidechain using a Proof-of-Stake consensus mechanism with periodic checkpoints to Ethereum mainnet. Validators stake MATIC tokens to participate in block production and verification. The architecture supports multiple scaling solutions including Polygon zkEVM, Supernets, and the CDK framework for app-specific chains.