Overview
Protocol extensible developer APIs and languages is a Layer 3 component.
Examples are: web3.js ether.js oo7.js Solidity * Rust
web3.js
Overview
This is the Ethereum compatible JavaScript API which implements the Generic JSON RPC spec. It's available on npm as a node module, for bower and component as an embeddable js and as a meteor.js package.
Resources
ethers.js
Overview
Complete Ethereum wallet implementation and utilities in JavaScript.
Resources
oo7.js
Overview
A small library providing what might be termed as reactive expressions, Bonds (hence the name). Classes deriving from Bond are expected to determine when their value has changed and call trigger accordingly.
Resources
Solidity
Overview
Solidity is a contract-oriented, high-level language for implementing smart contracts. It was influenced by C++, Python and JavaScript and is designed to target the Ethereum Virtual Machine (EVM).
Solidity is statically typed, supports inheritance, libraries and complex user-defined types among other features.
Resources
Rust
Overview
Rust is a systems programming language that runs blazingly fast, prevents segfaults, and guarantees thread safety.