name: implement-arc-standards
description: Implement Algorand ARC standards in smart contracts and clients. Use when needing to understand ARC-4 ABI encoding or method signatures, working with application specifications (ARC-32 or ARC-56), calling ARC-4 methods from contracts or clients, encountering ABI encoding/decoding issues, or generating typed clients from app specs. Strong triggers include "What is ARC-4?", "How do I encode ABI arguments?", "What's the difference between ARC-32 and ARC-56?", "method selector not matching", "application specification", "arc56.json".

Implement ARC Standards

ARC (Algorand Request for Comments) standards define conventions for encoding, method calls, and application specifications on Algorand. This skill covers the most essential ARCs for smart contract development.

Overview / Core Workflow

1. Understand which ARC applies to your use case
2. Implement the contract following ARC conventions
3. Generate application specification files
4. Use the app spec to build typed clients

How to proceed

Key ARCs for Smart Contract Development

ARC-4: The Foundation

ARC-4 defines how to encode method calls and data types for Algorand smart contracts.

Method Signatures

A method signature uniquely identifies a method: name(arg_types)return_type

# Method signature: add(uint64,uint64)uint128
# Method selector: first 4 bytes of SHA-512/256 hash

from algopy import ARC4Contract, arc4

class Calculator(ARC4Contract):
    @arc4.abimethod
    def add(self, a: arc4.UInt64, b: arc4.UInt64) -> arc4.UInt128:
        return arc4.UInt128(a.native + b.native)

import { Contract } from '@algorandfoundation/algorand-typescript'
import { abimethod, UInt64, UInt128 } from '@algorandfoundation/algorand-typescript/arc4'

class Calculator extends Contract {
  @abimethod()
  add(a: UInt64, b: UInt64): UInt128 {
    return new UInt128(a.native + b.native)
  }
}

Method Selector Calculation

Method signature: add(uint64,uint64)uint128
SHA-512/256 hash: 8aa3b61f0f1965c3a1cbfa91d46b24e54c67270184ff89dc114e877b1753254a
Method selector: 8aa3b61f (first 4 bytes)

ARC-32 vs ARC-56

Use ARC-56 for new projects. ARC-32 is maintained for backwards compatibility.

Generating App Specs

App specs are automatically generated when compiling with PuyaPy or PuyaTs:

# Generates ContractName.arc32.json and ContractName.arc56.json
algokit project run build

Using App Specs with Clients

// TypeScript with AlgoKit Utils
import { algorandClient } from '@algorandfoundation/algokit-utils'
import appSpec from './Calculator.arc56.json'

const client = algorand.client.getTypedAppClientById(CalculatorClient, {
  appId: 12345n,
  appSpec,
})

const result = await client.send.add({ args: { a: 10n, b: 20n } })

# Python with AlgoKit Utils
from algokit_utils import AlgorandClient
from artifacts.calculator_client import CalculatorClient

algorand = AlgorandClient.default_localnet()
client = algorand.client.get_typed_app_client(
    CalculatorClient,
    app_id=12345,
)

result = client.send.add(a=10, b=20)

Important Rules / Guidelines

Common Variations / Edge Cases

References / Further Reading

• ARC-4 ABI Details - Types, encoding rules, method invocation
• ARC-32/56 App Specs - Application specification details
• ARC Standards - Official ARC documentation
• Call Smart Contracts - Using AlgoKit Utils for ABI calls