Developer builder tools

Highlights

Web3j is the Java and Android integration library for Ethereum. Created in 2016, and still going strong in 2025 it is core plumbing to Ethereum for one of the world's most widely used development platforms, the JVM. It has been downloaded millions of times, and is used by everyone including Enterprises such as J.P. Morgan, Fnality and NTT Data Web3 infrastructure companies such as Alchemy The Besu Ethereum Execution client It's even been integrated natively into the Android OS by Freedom Factory in ethOS which powers the upcoming Ethereum phone the DGEN1 We decided in 2024 to bring Web3j into the Hyperledger Foundation, which provides high-quality governance of open source (similar to the Apache Foundation). It's still, the same team at Web3 Labs responsible for maintaining and supporting the library for its wide and varied user base. The Hyperledger association is great for visibility, but doesn't provide any funding for the project! We rely on grant funding to sustain this library and hopeful to qualify for this RPGF round. Unfortunately, we missed out on OP RPGF 3 as we had not realised projects were eligible for multiple rounds so did not apply following our success in OP RPGF 2. 🙏🏻

Client libraries & SDKs (front-end)

Web3j

Governance · CLI

Passport is the premier web3 native offering that enables ecosystems to protect, understand and organically grow what matters most – their communities. We see Passport at the confluence of a best in class identity solution, backed by the most relevant and comprehensive data analysis toolset that also offers communities the ability to ascribe reputation.

Data, analytics & tracing

Passport XYZ | Gitcoin Passport

Analytics · Gas efficient

miniapp starters is a set of open-source starter templates designed to make it easier to build Farcaster miniapps, with support for Worldcoin integrations as well. Miniapp Starters came out of our own journey building miniapps. Along the way, we found ourselves creating common patterns and components repeatedly, so we decided to turn that work into a set of reusable, community-friendly templates. Now, anyone can kickstart their own miniapp projects without reinventing the wheel.

Education & community resources

miniapp starters

Education · Farcaster · Next.js · TailwindCSS · Type-safe · Analytics

Applications

Cross-chain & interoperability

LI.FI

Cross-chain · API · DEX aggregator · Multi-chain · Performance optimization

L2Pass

Cross-chain · Wallet · Multi-chain

OP ENS Gateway by Opti.Domains

Cross-chain · Governance · Layer 2 · Verification · Scalability

Titan Layer

Cross-chain · Security

Stargate Finance

Cross-chain · DeFi

Transaction & wallet infrastructure

LlamaPay

DeFi · Gas efficient

Candide's Smart Account Contracts

Wallet · Governance · Education · Account abstraction · User experience

Curvegrid MultiBaas

DeFi

ethereum-multicall

Multicall

Governance Onchain Paymaster

Account abstraction · Developer experience

Data, analytics & tracing

Blockhead

Block explorer

Blockscout open-source block explorer

Block explorer · Chains

Patterns wallet analytics & CRM

Analytics · DeFi · Visualization · Docker · Scalability

Ethereum RPC MCP Server

MCP server · Contract verification

Ethernal

Analytics · Block explorer · Chains · Contract verification · CLI

Education & community resources

ERC-4337 Documentation

Account abstraction · Education · page-developers-tools-tag-standards-and-specifications

Academy

Education

Ethereum MCP

MCP server · page-developers-tools-tag-standards-and-specifications

The Ethernaut

Education · Security · Solidity · Community driven · React app

Ethereum EIPs Ontology

Education · page-developers-tools-tag-standards-and-specifications

Client libraries & SDKs (front-end)

Black Scholes library/compiler - go and rust

DeFi · Gas optimization

evmstate

Analytics · Storage layout

go-libp2p

Governance · libp2p · Peer-to-peer · Networking · Encryption · GossipSub · Community driven

Gelato Relay SDK

Security · SDK

Frames.js

Frontend · Farcaster · React · Next.js

Smart contract development & toolchains

Hermes - a GossipSub listener and tracer for libp2p-based networks.

Governance · GossipSub · libp2p · CLI

Farcaster Attestation

Governance · Solidity · Farcaster

EvmTools

CLI · Analytics · Debugging tools · Transaction decoding · Merkle trees

AWS KMS and YubiHSM signer for OP Stack

Security · Docker · Transaction signing

foundry-storage-check

Foundry · CLI · DevOps · GitHub actions · Solidity · Storage layout · Code quality · Security

Security, testing & formal verification

blocksmith.js

CLI · Foundry · Cross-chain · Contract deployment

Chimera

Foundry · Solidity · Code coverage · Test automation · VSCode extension

Wallet Test Framework

Testing · Wallet · User experience · Developer experience · Security

Kontrol - formal verification tool based on Foundry and KEVM

Foundry · Education · Governance · Formal verification · Solidity · Runtime verification · Contract deployment · Static analysis

Trail of Bits Skills Marketplace

Security · Testing · page-developers-tools-tag-agent-skills