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2.0.2 • Public • Published

Leopard Binding for React Native

Leopard Speech-to-Text Engine

Made in Vancouver, Canada by Picovoice

Leopard is an on-device speech-to-text engine. Leopard is:

  • Private; All voice processing runs locally.
  • Accurate
  • Compact and Computationally-Efficient
  • Cross-Platform:
    • Linux (x86_64), macOS (x86_64, arm64), Windows (x86_64)
    • Android and iOS
    • Chrome, Safari, Firefox, and Edge
    • Raspberry Pi (4, 3) and NVIDIA Jetson Nano


This binding is for running Leopard on React Native 0.62.2+ on the following platforms:

  • Android 5.0+ (SDK 21+)
  • iOS 11.0+


To start install, be sure you have installed yarn and cocoapods. Then, add the following native modules to your react-native project:

yarn add @picovoice/leopard-react-native


npm i @picovoice/leopard-react-native --save

Link the iOS package

cd ios && pod install && cd ..

NOTE: Due to a limitation in React Native CLI auto-linking, the native module cannot be included as a transitive dependency. If you are creating a module that depends on leopard-react-native, you will have to list these as peer dependencies and require developers to install it alongside.


Leopard requires a valid Picovoice AccessKey at initialization. AccessKey acts as your credentials when using Leopard SDKs. You can get your AccessKey for free. Make sure to keep your AccessKey secret. Signup or Login to Picovoice Console to get your AccessKey.


Create an instance of Leopard:

import { Leopard, LeopardErrors } from '@picovoice/leopard-react-native'

const accessKey = "${ACCESS_KEY}" // AccessKey obtained from Picovoice Console (https://console.picovoice.ai/)
const modelPath = "${LEOPARD_MODEL_PATH}" // path relative to the assets folder or absolute path to file on device

try {
    const leopard = await Leopard.create(accessKey, modelPath)
} catch (err: any) {
  if (err instanceof LeopardErrors) {
    // handle error

Transcribe an audio file by passing the file path to Leopard:

try {
  const { transcript, words } = await leopard.processFile("${AUDIO_FILE_PATH}")
} catch (err: any) {
  if (err instanceof LeopardErrors) {
    // handle error

Finally, when done be sure to explicitly release the resources using leopard.delete().

Language Model

Create a custom model using the Picovoice Console or use one of the default language models found in lib/common.

Adding to Android

To add a Leopard model file to your Android application, add the file as a bundled resource by placing it under the assets directory of your Android application.

Adding to iOS

To add a Leopard model file to your iOS application, add the file as a bundled resource by selecting Build Phases in Xcode and adding it to the Copy Bundle Resources step.

Word Metadata

Along with the transcript, Leopard returns metadata for each transcribed word. Available metadata items are:

  • Start Time: Indicates when the word started in the transcribed audio. Value is in seconds.
  • End Time: Indicates when the word ended in the transcribed audio. Value is in seconds.
  • Confidence: Leopard's confidence that the transcribed word is accurate. It is a number within [0, 1].
  • Speaker Tag: If speaker diarization is enabled on initialization, the speaker tag is a non-negative integer identifying unique speakers, with 0 reserved for unknown speakers. If speaker diarization is not enabled, the value will always be -1.

Demo App

For example usage refer to our React Native demo application.

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npm i @picovoice/leopard-react-native

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