Halo2 excels at scalability and developer flexibility because it uses a polynomial commitment scheme (IPA) that eliminates the need for a trusted setup and enables recursive proof composition. For example, zkSync Era leverages Halo2 to achieve over 100 TPS on mainnet, supporting complex smart contracts with its custom LLVM-based compiler. Its lookup arguments allow for efficient handling of non-arithmetic operations, making it a strong choice for general-purpose EVM compatibility.
LABS
Comparisons
Halo2 vs Groth16: Proving Choice
An in-depth technical and strategic comparison of the Halo2 and Groth16 zero-knowledge proving systems, analyzing their trade-offs for CTOs and protocol architects building ZK rollups.
Chainscore © 2026
introduction
THE ANALYSIS
Introduction: The Proving Engine Decision
Choosing between Halo2 and Groth16 is a foundational decision that defines your zk-rollup's performance, cost, and upgrade path.
Groth16 takes a different approach by using pairing-based cryptography and a one-time trusted setup. This results in extremely small proof sizes (~200 bytes) and the fastest on-chain verification times, a critical metric for minimizing L1 gas costs. Protocols like Zcash and early Loopring rely on its battle-tested security. The trade-off is rigidity: each circuit requires its own trusted setup, and supporting dynamic logic or upgrades is significantly more complex.
The key trade-off: If your priority is future-proof scalability, recursive proofs, and avoiding trusted setup ceremonies, choose Halo2. It's the engine behind next-generation L2s like Polygon zkEVM and Scroll. If you prioritize minimizing on-chain verification gas costs to the absolute theoretical limit for a fixed, high-value application, choose Groth16. Your decision hinges on whether you value long-term flexibility or immediate, optimized cost for a proven circuit.
tldr-summary
Halo2 vs Groth16: Proving Choice
TL;DR: Key Differentiators at a Glance
A data-driven breakdown of the core trade-offs between the two dominant zk-SNARK proving systems.
01
Halo2: Recursive Proofs & Flexibility
Enables recursive proof composition via its accumulator-based architecture (e.g., used in zkEVM rollups). This is critical for scalable L2s like Scroll and Taiko. Offers customizable proving systems (e.g., Plonkish arithmetization) for complex logic, making it ideal for application-specific circuits.
02
Halo2: No Trusted Setup
Operates with a transparent setup, eliminating the need for a trusted ceremony. This removes a major security assumption and operational overhead, which is a decisive factor for new protocols prioritizing decentralization and long-term security guarantees.
03
Groth16: Unmatched Proving Efficiency
Delivers the smallest proof sizes (~128 bytes) and fastest verification times of any production zk-SNARK. This is non-negotiable for high-frequency on-chain verification, such as privacy applications in Zcash or optimistic rollup fraud proofs.
04
Groth16: Maturity & Tooling
Battle-tested since 2016 with billions in secured value (e.g., Zcash, Mina Protocol). Has a mature ecosystem of libraries (bellman, snarkjs) and developer tools. This reduces integration risk for enterprise projects requiring proven stability.
ZK-PROVING SYSTEM COMPARISON
Feature Comparison: Halo2 vs Groth16
Direct comparison of key technical and operational metrics for two leading zk-SNARK proving systems.
| Metric / Feature | Halo2 | Groth16 |
|---|---|---|
Trusted Setup Required | ||
Proof Size | ~1-2 KB | ~200-300 bytes |
Prover Time (Complex Circuit) | ~3-5 sec | ~15-30 sec |
Recursion / Aggregation | ||
Universal Circuit Support | ||
Primary Use Case | Scalable L2s (zkRollups) | Private Transactions |
Notable Implementations | Scroll, Taiko, Polygon zkEVM | Zcash, Tornado Cash |
HEAD-TO-HEAD COMPARISON
Halo2 vs Groth16: Prover Performance & Cost
Direct comparison of proving system metrics for protocol architects selecting a ZK-SNARK backend.
| Metric | Groth16 | Halo2 (KZG) |
|---|---|---|
Universal Setup Required | ||
Proof Size (bytes) | ~200 | ~1,200 |
Prover Time (Complex Circuit) | ~30 sec | ~5 sec |
Verifier Time (on-chain) | < 10 ms | < 30 ms |
Recursive Proof Support | ||
Trusted Setup Ceremony | Powers of Tau | None required |
Library Maturity | High (libsnark, bellman) | High (ZCash, Scroll) |
pros-cons-a
PROS AND CONS
Halo2 vs Groth16: Proving Choice
Key strengths and trade-offs for two dominant zk-SNARK proving systems. Choose based on your protocol's stage and performance needs.
01
Halo2: Recursive Proofs
Native recursion without trusted setup: Enables proof aggregation and incremental verification. This is critical for scaling L2s like Scroll and Polygon zkEVM, allowing them to compress thousands of transactions into a single succinct proof.
02
Halo2: Developer Flexibility
Plonkish arithmetization & custom gates: Offers fine-grained control over circuit design for complex logic. This matters for custom VM implementations (e.g., zkWASM) and high-performance applications where Groth16's R1CS is too rigid.
03
Groth16: Proving Speed
Fastest prover for single proofs: Benchmarks show Groth16 is 2-5x faster than Halo2 for generating individual proofs. This is essential for privacy applications like Zcash, where low-latency proof generation for single transactions is paramount.
04
Groth16: Verification Efficiency
Smallest proof size & fastest verifier: Produces a constant 3 elliptic curve points (~128 bytes). This leads to the lowest on-chain gas costs, making it the historical choice for Ethereum L1 verification in projects like Tornado Cash.
05
Halo2: Con - Prover Complexity
Higher memory overhead and slower single-proof generation compared to Groth16. The flexibility of Plonkish arithmetization requires more sophisticated tooling (like the halo2 library) and can be overkill for simple, static circuits.
06
Groth16: Con - Circuit Rigidity
Requires a per-circuit trusted setup (MPC) and uses the less flexible R1CS. Any circuit change invalidates the setup, making it unsuitable for rapidly evolving protocols or those needing recursive composition without complex wrapping.
pros-cons-b
Halo2 vs Groth16: Proving Choice
Groth16: Pros and Cons
Key strengths and trade-offs at a glance for two dominant ZK-SNARK proving systems.
01
Groth16: Unmatched Proving Speed
Specific advantage: Single, fixed-size proof (~200 bytes) with the fastest prover in the category. This matters for high-throughput, cost-sensitive applications like private payments (e.g., Zcash Sapling) where on-chain verification gas costs are paramount.
< 10 ms
Verification Time
03
Halo2: No Trusted Setup & Recursion
Specific advantage: Uses a universal, updatable SRS (Structured Reference String) and natively supports proof recursion. This matters for building complex, scalable state machines like zkEVMs (e.g., Scroll, Taiko) and privacy rollups where chaining proofs is essential.
Recursion
Native Support
04
Halo2: Higher Proving Overhead
Specific disadvantage: Larger proof sizes and slower proving times compared to Groth16. This matters for user-facing applications (e.g., a wallet proving ownership) where proving latency and cost directly impact user experience.
CHOOSE YOUR PRIORITY
When to Choose Halo2 vs Groth16
Halo2 for Developers
Verdict: The modern, flexible choice for new, complex applications. Strengths:
- No Trusted Setup: Eliminates the complex, risky MPC ceremony required by Groth16, simplifying project launch.
- Recursive Proofs: Native support for recursion (proofs of proofs) enables scalable L2s and privacy-preserving rollups like Aztec.
- Custom Gates & Lookups: Programmable constraint system allows for highly optimized circuits, reducing proof size and cost for specific operations (e.g., EVM bytecode, cryptographic primitives). Trade-off: The ecosystem and tooling (halo2-lib, halo2_proofs) are newer and less battle-hardened than Groth16's (circom, snarkjs).
Groth16 for Developers
Verdict: The stable, performant standard for well-defined, production circuits. Strengths:
- Mature Tooling: Extensive libraries (circom, snarkjs), tutorials, and community support. Integration with Tornado Cash and zkSync Lite demonstrates proven patterns.
- Extremely Fast Verification: Small, constant-sized proofs (128 bytes) lead to the lowest on-chain verification gas costs, critical for Ethereum mainnet.
- Predictable Performance: Well-understood proving/verification times for circuits of known size. Trade-off: The trusted setup is a significant operational overhead and security consideration for each new circuit.
verdict
THE ANALYSIS
Final Verdict and Decision Framework
A data-driven breakdown to guide your choice between Halo2 and Groth16 for zero-knowledge proof systems.
Halo2 excels at scalability and developer flexibility due to its recursive proof composition and custom constraint system (Plonkish arithmetization). For example, projects like zkEVM Linea and Scroll leverage Halo2 to achieve high throughput for complex, stateful applications, enabling proofs for entire Ethereum blocks. Its ability to generate proofs without a trusted setup reduces operational overhead for long-running systems.
Groth16 takes a different approach by optimizing for succinctness and on-chain verification cost. This results in the smallest proof sizes (~128 bytes) and fastest verifier times, a critical metric for high-frequency, low-value on-chain transactions. However, it requires a circuit-specific trusted setup and lacks native recursion, making it less flexible for evolving protocols like Tornado Cash or Zcash which use it for its proven security and efficiency in fixed circuits.
The key trade-off is between future-proof flexibility and battle-tested optimization. If your priority is building a complex, evolving application (e.g., a zkRollup) where developer agility and recursive proofs are paramount, choose Halo2. If you prioritize minimizing on-chain gas costs for a fixed, high-security circuit (e.g., a token mixer or simple DEX) and value a mature, audited codebase, choose Groth16.
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