December 2, 2025

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The Zama Team

Bounty Track December 2025: Build The FHEVM Example Hub

The Zama Bounty Program aims to inspire and incentivize the developer community to contribute to the Zama Confidential Blockchain Protocol.

Each season, we introduce a new bounty that addresses a specific challenge. With this initiative, we invite developers to collaborate with us in advancing the FHE ecosystem.

For this season, the challenge is to build a set of standalone, Hardhat-based FHEVM example repositories, each demonstrating one clear concept (e.g., access control, public decryption, user decryption), with clean tests, automated scaffolding, and self-contained documentation. The prize pool for this challenge is $10,000.

Important dates

Start date: December 1, 2025
Submission deadline: December 31, 2025 (23:59, Anywhere On Earth)

Overview

The goal of this bounty is to create a comprehensive repository including standalone FHEVM examples that help developers learn and implement privacy-preserving smart contracts using Fully Homomorphic Encryption.

A starter example implementation of this bounty can be found here.

This repository demonstrates:

Automated scaffolding tools for generating example repositories
Documentation generation from code annotations
Category-based project generation
Complete implementation of the bounty requirements

How to participate

Participants should create a repository containing:

Automation scripts - TypeScript-based CLI tools for generating example repositories
Example contracts - Well-documented Solidity contracts demonstrating FHEVM concepts
Comprehensive tests - Test suites showing both correct usage and common pitfalls
Documentation generator - Tool to create GitBook-compatible documentation
Base template - Using our Hardhat template which can be cloned and slightly customized

Check out the example implementation to see:

How to structure your automation scripts
Example contract and test patterns
Documentation generation workflow
Category-based project generation

Requirements

1. Project structure & simplicity

Use only Hardhat for all examples
One repo per example, no monorepo
Keep each repo minimal: contracts/, test/, hardhat.config.ts, etc.
Use a shared base-template that can be cloned/scaffolded
Generate documentation like seen in /example relates to page.

2. Scaffolding / Automation

Create a CLI or script ([.c-inline-code]create-fhevm-example[.c-inline-code]) to:

Clone and slightly customize the base Hardhat template
Insert a specific Solidity contract into [.c-inline-code]contracts/[.c-inline-code]
Generate matching tests
Auto-generate documentation from annotations in code

Example implementation: See the example project for working [.c-inline-code]create-fhevm-example.ts[.c-inline-code] and [.c-inline-code]create-fhevm-category.ts[.c-inline-code] scripts written in TypeScript.

3. Types of examples to include (each of these becomes a standalone repo):

Examples that we already have

Basic:

Simple FHE counter
Arithmetic (FHE.add, FHE.sub)
Equality comparison (FHE.eq)

Encryption:

Encrypt single value
Encrypt multiple values

User decryption:

User decrypt single value
User decrypt multiple values

Public decryption:

Single value public decrypt
Multi value public decrypt

Additional example items to include

Access control

What is access control
FHE.allow, FHE.allowTransient

Input proof explanation

What are input proofs and why they're needed
How to use them correctly

Anti-patterns

View functions with encrypted values (not allowed)
Missing FHE.allowThis() permissions
Other common mistakes

Understanding handles

How handles are generated
Symbolic execution
Handle lifecycle

OpenZeppelin confidential contracts: (this can be found in previous versions, which needs an upgrade and import of this library)

ERC7984 example
ERC7984 to ERC20 Wrapper
Swap ERC7984 to ERC20
Swap ERC7984 to ERC7984
Vesting Wallet
...

Advanced examples:

Blind auction

Or anything else that you can think of.

4. Documentation strategy

Use JSDoc/TSDoc-style comments in TS tests
Auto-generate markdown README per repo
Tag key examples into docs: "chapter: access-control", "chapter: relayer", etc.
Generate GitBook-compatible documentation

Example implementation: See [.c-inline-code]generate-docs.ts[.c-inline-code] in the example project for automated documentation generation in TypeScript.

Bonus points:

Creative examples - Implementing additional examples beyond the requirements
Advanced patterns - Demonstrating complex FHEVM patterns and use cases
Clean automation - Particularly elegant and maintainable automation scripts
Comprehensive documentation - Exceptional documentation with detailed explanations
Testing coverage - Extensive test coverage including edge cases
Error handling - Examples demonstrating common pitfalls and how to avoid them
Category organization - Well-organized categories for different example types
Maintenance tools - Tools for updating examples when dependencies change

Judging criteria

All submissions must include a demonstration video as a mandatory requirement. The video should clearly showcase your project's setup, key features, example execution, and automation scripts in action.

Judging will be based on:

Code quality
Automation completeness
Example quality
Documentation
Ease of maintenance on new version changes
Innovation

Deliverables

Your submission must include:

base-template/ - Complete Hardhat template with [.c-inline-code]@fhevm/solidity[.c-inline-code]
Automation scripts - [.c-inline-code]create-fhevm-example[.c-inline-code] and related tools in TypeScript
Example repositories - Multiple fully working example repos (or category-based projects)
Documentation - Auto-generated documentation per example
Developer guide - Guide for adding new examples and updating dependencies
Automation tools - Complete set of tools for scaffolding and documentation generation