react-native-altcha

ALTCHA React Native Widget

The AltchaWidget is a CAPTCHA-like React Native component that provides a secure, privacy-friendly way to verify that a user is human — without the frustration of traditional CAPTCHAs. It uses a cryptographic proof-of-work mechanism combined with an optional code challenge, making it resilient against bots and spam.

ALTCHA is an open-source alternative to traditional CAPTCHA, designed to be fast, accessible, and privacy-respecting.

For more information and documentation, visit altcha.org.

Features

• Native React Native component – no WebView required
• Privacy-friendly, CAPTCHA-like verification
• Supports image and audio code challenges with ALTCHA Sentinel (adaptive CAPTCHA)
• Localization support for multiple languages
• Light and Dark theme support

Screenshots

Installation

Install peer dependencies

npx expo install expo-audio expo-crypto expo-localization react-native-svg

With npm:

npm install react-native-altcha

Or with Yarn:

yarn add react-native-altcha

Usage

import React from 'react';
import { View } from 'react-native';
import { AltchaWidget } from 'react-native-altcha';

export default function App() {
  return (
    <View style={{ padding: 16 }}>
      <AltchaWidget
        challengeUrl="https://api.example.com/altcha/challenge"
        debug={true}
        onVerified={(payload) => {
          // Send the payload to your backend
          console.log('Payload:', payload);
        }}
      />
    </View>
  );
}

Props

One of challengeUrl or challengeJson is required. The widget will return the ALTCHA payload via onVerified, which you should send to your server for verification.

Prop	Type	Description
challengeUrl	string	URL to fetch the challenge JSON
challengeJson	object	Challenge object provided directly
colorScheme	'light' | 'dark'	Force color scheme (optional, otherwise follows system)
locale	string	Language to use (defaults to en)
onFailed	(error: any) => void	Called with an error on verification failure
onVerified	(payload: string) => void	Called with encoded payload after verification
onServerVerification	(result: any) => void	Called with server verification result
delay	number	Optional delay before solving (ms)
debug	boolean	Enable verbose logging
hideLogo	boolean	Hide the ALTCHA logo
hideFooter	boolean	Hide the footer text
httpHeaders	Record<string,string>	Custom HTTP headers (optional)
themes	{ dark: {}, light: {} }	Override theme properties
customTranslations	Record<string,Translation>	Override default translations
verifyUrl	string	Server endpoint to verify the solution

Localization

The component includes built-in translations for multiple languages. You can pass a customTranslations prop to override or add custom text.

<AltchaWidget
  challengeUrl="https://api.example.com/altcha/challenge"
  locale="en"
  customTranslations={{
    en: {
      label: 'I am human',
    },
  }}
/>

Customization

You can customize the widget’s appearance using the style prop for layout and basic styling:

<AltchaWidget
  style={{
    backgroundColor: '#ddd',
    borderColor: '#0000ff',
    fontSize: 20,
    width: '100%',
  }}
/>

For color customization, use the themes prop to define separate color sets for light and dark modes:

<AltchaWidget
  themes={{
    dark: {
      primaryColor: '#00ff00',
    },
    light: {
      primaryColor: '#00ff00',
    },
  }}
/>

Available theme colors:

type AltchaTheme = {
  backgroundColor: string;
  borderColor: string;
  errorColor: string;
  primaryColor: string;
  primaryContentColor: string;
  textColor: string;
};

Example App

cd example
yarn install
yarn start

License

MIT