# Introduction
Thinkium is compatible with the development interface of Ethereum, so it can directly use the SDK of Ethereum for chain development.
Ethereum SDK docs: https://ethereum.org/zh/developers/docs/programming-languages/ (opens new window)
If you want to do cross-chain development, you need to download the official Thinkium SDK. Currently we provide four language versions JS, Java, Go, Python.
This document is easy to check what interfaces are supported on the chain. For specific usage, it is recommended to download the SDK of the corresponding language. There are detailed test cases in the SDK.
JS SDK address: https://github.com/ThinkiumGroup/web3.js (opens new window)
Java SDK address: https://github.com/ThinkiumGroup/web3j (opens new window)
Go SDK address: https://github.com/ThinkiumGroup/web3.go (opens new window)
Python SDK address: https://github.com/ThinkiumGroup/web3.py (opens new window)
Thinkium has a multi-chain structure, and account addresses have different asset status in different chains.
Currently supports 3 sub-chains:
chain 1 , account chain
chain 2 , POS chain
chain 103 , business chain (In the future, more sub-chains will be added according to the specific business)
RPC address: The RPC is used to interact with the chain. The following is the official RPC address. If you build the chain node yourself. You can deploy your own RPC service and connect to your own RPC address while development.
TestNet:
Account Chain : test1.thinkiumrpc.net chainId: 60001
PoS Chain : test2.thinkiumrpc.net chainId: 60002
Business Chain : test103.thinkiumrpc.net chainId : 60103
Cross Chain: test.thinkiumrpc.net
MainNet:
Account Chain : proxy1.thinkiumrpc.net chainId: 70001
PoS Chain : proxy2.thinkiumrpc.net chainId: 70002
Business Chain : proxy103.thinkiumrpc.net chainId : 70103
Cross Chain: proxy.thinkiumrpc.net