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Is Valid Signature

Is Valid Signature is a JavaScript library that checks whether a signature is valid for an Ethereum address, supporting externally owned accounts and contract accounts that implement the package’s documented ERC-1271 interface.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

Is Valid Signature — 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 an Ethereum application needs a reusable JavaScript check for signatures from EOAs or contract accounts using the documented ERC-1271 interface.

Who it is for

  • JavaScript developers building Ethereum applications.
  • Teams validating signed messages for EOAs and supported ERC-1271 contract accounts.

Documented uses

  • Check a signature associated with an EOA address.
  • Check a contract account’s signature through the supported ERC-1271 interface.
  • Add signature validation to a message-verification or login flow.
Before you choose

Requirements & limits

The repository lists an MIT license.

  • The examples pass a Web3 provider along with the address, message hash and signature.
  • Contract-account support is limited to the ERC-1271 interface shown in the README.

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

Check an Ethereum EOA signature

Use the documented JavaScript call to validate a signature for an externally owned account.

Before you start

  • Node.js project with the package installed using npm.
  • JavaScript and a Web3 provider, as used in the README.
  • Signer address, message hash and signature.

Steps

  1. Install the package with the command below.

    Documented command
    npm install is-valid-signature

  2. Import it with require('is-valid-signature').

  3. Pass the signer address, message hash, signature and web3.currentProvider to the library.

Expected outcome

The call returns an `isValid` result for the supplied signature and signer address.

Guide limitations

  • The README example uses Web3 methods to create the message hash and obtain a signature; it does not describe a complete authentication flow.
Documentation 1 ↗
Source-based practical guide

Check a signature for an ERC-1271 contract account

Use the documented JavaScript call to check a signature against a contract address through the package’s supported ERC-1271 interface.

Before you start

  • Node.js project with the package installed using npm.
  • JavaScript and a Web3 provider.
  • An ERC-1271 contract address, message hash and signature.

Steps

  1. Install the package with the command below.

    Documented command
    npm install is-valid-signature

  2. Import it with require('is-valid-signature').

  3. Pass the contract address, message hash, signature and web3.currentProvider to the library.

Expected outcome

The call returns an `isValid` result using the contract’s ERC-1271 signature check.

Guide limitations

  • The README says ERC-1271 has multiple proposed interfaces and identifies only the isValidSignature(bytes,bytes) interface returning bytes4 as supported.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
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Sources checked
16 October 2026
Original website title
authereum/is-valid-signature · Official homepage title · retained in its source language
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