Cardano smart contracts
Cardano smart contracts are programs on the Cardano blockchain that decide whether a transaction may spend an output, for example the funds in an exchange pool or the collateral of a loan. Cardano has supported them since the Alonzo hard fork of September 12, 2021, at epoch 290.
Developers write the contracts in languages such as Aiken or Plinth, which compile to Untyped Plutus Core, the code that every Cardano node runs. Because the contracts follow the extended UTXO model, a wallet knows the fee and the result of a transaction before it submits it.
Launch date and Plutus versions
Smart contracts went live on mainnet with the Alonzo hard fork on September 12, 2021, which introduced Plutus V1. The Vasil hard fork of 2022 brought Plutus V2 with reference inputs and inline datums, so several transactions can read the same data without spending it. Plutus V3 arrived with the Chang hard fork in 2024, which also started on-chain governance, and added cryptographic functions such as operations on the BLS12-381 curve.
Smart contract language: Aiken and Plinth
On Cardano, a smart contract is called a validator, a script that accepts or rejects a transaction that wants to spend an output it guards. Many new projects write validators in Aiken, a language built for Cardano that compiles to Untyped Plutus Core (UPLC). Plinth, formerly called Plutus Tx, lets developers write validators in Haskell, and further compilers such as OpShin for Python produce the same on-chain code.
The eUTXO model
Cardano uses the extended unspent transaction output (eUTXO) model, in which funds sit in outputs that a transaction consumes whole and replaces with new ones. A script output carries a datum with the stored state, and the spending transaction supplies a redeemer with the action it requests. The validator sees only the transaction and its inputs, so its result cannot change between building and submission, and a script that fails on chain costs only the collateral the user set aside.
Smart contract development and audits
The Cardano Developer Portal collects documentation and software development kits for developers who start on the network. The Cardano Academy teaches Aiken in ten modules and runs a course in which an AI coding agent writes validator code from a written specification. Before a contract handles money on mainnet, teams test it on the preview or pre-production network and commission a smart contract audit.
Smart contract example: programmable tokens
The CIP-0113 standard shows how validators and native tokens work together. A token issued under the standard carries rules that a validator checks at every transfer, such as a KYC check or a freeze ordered by the issuer. The standard went live on mainnet in October 2026, and regulated issuers of stablecoins and securities can now put their compliance rules into the token itself.
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Cardano smart contracts and Finance Loop
Finance Loop covers blockchain development in the Digital Infrastructure & Sovereignty track, where IT and architecture teams of banks and asset managers compare platforms. On Cardano, a bank that runs a contract for its clients knows the fee and the outcome of each transaction before it is sent.
Finance Loop is a professional network and has the goal of driving the institutional use of emerging technologies in finance, such as AI, digital payments, cloud and blockchain solutions. Finance Loop helps its members build skills and personal networks in these fields: Investment & Digital Assets, Payments & Digital Money, Digital Infrastructure & Sovereignty, and Risk & Compliance.