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ICON is a scalable smart contract enabled blockchain platform with a long-term goal of interoperability between enterprise and public blockchains. Our goal is to Hyperconnect the World, and by combining groundbreaking technology, a strong community, and relentless growth strategies we believe this goal is reachable.

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ICON Smart Contract - SCORE

SCORE (Smart Contract on Reliable Environment) is a smart contract running on ICON network. A contract is a software that resides at a specific address on the blockchain and executed on ICON nodes. They are building blocks for DApp (Decentralized App). SCORE defines and exports interfaces, so that other SCORE can invoke its functions. The code is written in python, and is uploaded as compressed binary data on the blockchain.

  • Deployed SCORE can be updated. SCORE address remains the same after update.
  • SCORE code size is limited to about 64 KB (actually bounded by the maximum stepLimit value during its deploy transaction) after compression.
  • SCORE must follow sandbox policy - file system access or network API calls are prohibited.


  • The maximum limit of the total count of call, interface call and ICX transfer/send is 1024 in one transaction.
  • The limitation of stack size increment by calling external SCORE is 64 in one transaction.
  • Declaring member variables which are not managed by states is prohibited.


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