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WEB3 Input Decoder

WEB3 Input Decoder is an open-source Python library that decodes Ethereum transaction input for smart-contract function calls and constructor arguments using a contract ABI. It provides standalone decoding functions and an InputDecoder class for repeated decoding with the same ABI.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

WEB3 Input Decoder — OpenViST project profile in Developer Tools.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use it when a Python workflow needs to interpret Ethereum transaction input and the relevant contract ABI is available.

Who it is for

  • Python developers building Ethereum contract analysis tools.
  • Developers inspecting decoded arguments from transaction calldata.
  • Developers examining constructor parameters in contract deployment input.

Documented uses

  • Turn function-call transaction input into named, typed argument values.
  • Decode constructor arguments using a contract ABI.
  • Reuse an ABI-bound InputDecoder for repeated function-input decoding.
Before you choose

Requirements & limits

The project documents installation with pip and links to a Replit quick-start. Its repository lists an MIT license.

  • Decoding depends on having the contract ABI; the README demonstrates fetching an ABI from Etherscan with an API key.
  • The documented API accepts transaction input as a string or bytes and returns type-name-value tuples.
  • The README describes the decoder as offline; an external ABI lookup is a separate step in its example.
  • InputDecoder is offered for repeated decoding associated with one contract ABI.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Install the Python package

Add WEB3 Input Decoder to a Python environment before using its documented decoding functions.

Before you start

  • A Python environment with pip.

Steps

  1. Run the command below.

    Documented command
    pip install web3-input-decoder

  2. Import decode_function and decode_constructor from web3_input_decoder.

Expected outcome

The package is installed and its documented decoding functions can be imported.

Guide limitations

  • This covers installation and imports only; decoding requires transaction input and the relevant contract ABI.
Documentation 1 ↗
Source-based practical guide

Decode function or constructor input

Use a contract ABI and transaction input with the corresponding documented decoder.

Before you start

  • The package installed in a Python environment.
  • A contract ABI and transaction input data.
  • For constructor decoding, deployed contract bytecode may be supplied separately when the input includes bytecode.

Steps

  1. Import decode_function and decode_constructor from web3_input_decoder.

  2. Pass the ABI and transaction input to decode_function for a function call.

  3. Pass the ABI and constructor input to decode_constructor; provide the optional bytecode argument when applicable.

Expected outcome

The documented functions return decoded type-name-value tuples.

Guide limitations

  • The decoder needs the relevant ABI; the README's example retrieves one through the Etherscan API using an API key.
  • This workflow decodes input data and does not document sending transactions.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
Active
Sources checked
13 October 2026
Original website title
kigawas/web3-input-decoder · Official homepage title · retained in its source language
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