What is ZK-Kit?

ZK-Kit is a comprehensive suite of production-ready zero-knowledge libraries designed to simplify the development of privacy-preserving applications. Built and maintained by the Privacy & Scaling Explorations team, ZK-Kit provides battle-tested implementations of cryptographic primitives across multiple programming languages.

Overview

ZK-Kit is a set of libraries (algorithms or utility functions) that can be reused in different projects and zero-knowledge protocols, making it easier for developers to access user-friendly, tested, and documented code for common tasks.

Key Features:

• Super lightweight
• TypeScript type support
• Comprehensive code documentation
• Full test coverage
• Browser and NodeJS compatible
• Multiple language implementations

Core Components

Merkle Trees

Build privacy-preserving membership systems with three variants:

• IMT (Incremental Merkle Tree): Standard choice for most applications
• LeanIMT: Memory-optimized for resource-constrained environments
• SMT (Sparse Merkle Tree): Key-value storage with non-membership proofs

Cryptographic Primitives

• EdDSA-Poseidon: Digital signatures optimized for zero-knowledge circuits
• Poseidon Cipher: Encryption/decryption for ZK-friendly data
• Baby Jubjub: Elliptic curve operations
• Poseidon Proof: Generate and verify ZK proofs

Utilities

• Utils: Field operations, conversions, scalar arithmetic
• Logical Expressions: Boolean logic in zero-knowledge

Why ZK-Kit?

🔒 Battle-Tested

Used in production by:

• Semaphore Protocol: Anonymous signaling
• Worldcoin: Proof of personhood protocol
• MACI: Anti-collusion voting
• Privacy Pools: Private transactions
• Zupass: Privacy-preserving tickets

⚡ Developer-Friendly

// Install
npm i @zk-kit/imt
// + peer dependencies (check npm page)

// Use
import { IMT } from "@zk-kit/imt"
import { poseidon2 } from "poseidon-lite" // peer dependency

const tree = new IMT(poseidon2, 16, 0, 2)
tree.insert(BigInt(1))
const proof = tree.createProof(0)
console.log(tree.verifyProof(proof)) // true ✓

🎯 Modular Design

• Tree-shakeable builds
• Minimal dependencies
• Composable components
• Language-specific optimizations

🚀 Production-Ready

• Comprehensive test coverage
• Security audits
• Performance benchmarks
• Real-world usage patterns

Architecture

ZK-Kit follows a modular architecture where each package is independent and composable:

┌─────────────────────────────────────────┐
│           Your Application              │
└─────────────────────────────────────────┘
                    │
    ┌───────────────┼───────────────┐
    │               │               │
┌───▼────┐    ┌────▼─────┐   ┌────▼─────┐
│ Merkle │    │  Crypto  │   │ Utilities│
│ Trees  │    │ Primitives│   │          │
└────────┘    └──────────┘   └──────────┘

Language Support

ZK-Kit is available in 5 languages for different use cases:

Language	Packages/Circuits	Repository	Primary Use Case
JavaScript/TypeScript	9 packages	privacy-scaling-explorations/zk-kit	Web apps, Node.js (this documentation)
Circom	5+ circuits	privacy-scaling-explorations/zk-kit.circom	zkSNARK circuit development
Noir	4 packages	privacy-scaling-explorations/zk-kit.noir	Aztec protocol, Noir circuits
Solidity	4 contracts	privacy-scaling-explorations/zk-kit.solidity	Ethereum smart contracts
Rust	3 packages	privacy-scaling-explorations/zk-kit.rust	High-performance backends

Cross-language compatibility: All implementations use the same algorithms, so proofs generated in TypeScript can be verified in Solidity!

→ Explore all language implementations

Use Cases

ZK-Kit enables a wide range of privacy-preserving applications:

Identity & Authentication

• Anonymous credentials
• Self-sovereign identity
• Privacy-preserving KYC
• Reputation systems

Voting & Governance

• Anonymous voting
• Anti-collusion mechanisms
• Delegation systems
• Quadratic voting

DeFi & Payments

• Private transactions
• Compliance proofs
• Anonymous airdrops
• Privacy pools

Social & Gaming

• Anonymous messaging
• Hidden information games
• Private leaderboards
• Fair randomness

Getting Started

Choose your path:

• New to ZK? → Start with Why Zero-Knowledge?
• Ready to code? → Jump to Quick Start
• Need a specific package? → Check Choosing a Package
• Deep concepts? → Explore Core Concepts

Community & Support

• GitHub: github.com/privacy-scaling-explorations/zk-kit
• Discussions: GitHub Discussions
• Issues: Bug Reports & Feature Requests

License

ZK-Kit is open source and released under the MIT License.

Next Steps

• Why Zero-Knowledge? - Understand the problem ZK solves
• Comparison - How ZK-Kit compares to alternatives
• Ecosystem - Projects built with ZK-Kit
• Quick Start - Start building with ZK-Kit