Building Apps for Voice Assistants: Best Practices

Voice assistants, like Amazon Alexa, Google Assistant, and Apple’s Siri, have become integral to how users interact with technology. From setting reminders to making purchases, these AI-powered assistants are reshaping digital experiences. For developers, building voice apps (often referred to as “skills” or “actions”) offers exciting opportunities but also requires careful consideration of user experience, voice interface design, and performance.

In this blog, we’ll explore the best practices for building apps for voice assistants, covering design principles, usability tips, testing strategies, and the technical considerations essential for success.

Table of Contents:
1. Why Build for Voice Assistants?
2. Voice UI (VUI) Design Principles
3. Choosing the Right Voice Assistant Platform
4. Key Best Practices for Building Voice Assistant Apps
5. Tools and Frameworks for Developing Voice Apps
6. Testing and Optimizing Your Voice App
7. Challenges in Voice App Development
8. Future Trends in Voice Assistant Apps
9. Conclusion

1. Why Build for Voice Assistants?

Voice assistants have rapidly gained popularity due to their convenience, accessibility, and hands-free functionality. As more people use voice-activated devices, the demand for apps tailored to these platforms is growing. Here’s why building for voice assistants makes sense:

– Hands-Free Convenience: Users can interact with apps while multitasking, making voice apps ideal for situations where manual input is impractical (e.g., driving or cooking).
– Personalization: Voice assistants can provide highly personalized experiences, responding to individual preferences, commands, and context.
– Growing Market: According to reports, the number of voice assistant-enabled devices worldwide is expected to exceed 8 billion by 2024. Businesses that integrate voice apps can tap into this vast audience.
– Voice Commerce: The rise of voice-based shopping is creating opportunities for e-commerce businesses to offer streamlined purchasing experiences via voice assistants.

2. Voice UI (VUI) Design Principles

Unlike graphical user interfaces (GUI), voice user interfaces (VUI) require a different design approach. The key focus is on conversation flow and natural language interaction. Here are some essential VUI design principles:

a) Keep Conversations Natural
The most successful voice apps mimic natural human conversations. Aim for a friendly, conversational tone in your responses. Keep interactions intuitive by anticipating user queries and avoiding technical jargon.

b) Short and Simple Responses
Users interacting with voice assistants often want quick, actionable responses. Avoid overloading users with information. For example, if a user asks for the weather, provide the most relevant details concisely, rather than overwhelming them with unnecessary data.

c) Minimize User Memory Load
Don’t expect users to remember previous inputs, choices, or complex commands. Design your app so that each user interaction stands alone and provides enough context for the user to continue without needing to recall earlier steps.

d) Guiding Users with Prompts
Use clear, actionable prompts to guide users through a conversation. For instance, after a user makes a request, you can offer specific next steps, such as “Would you like to hear more about this product, or place an order?”

e) Error Handling
Users won’t always provide clear or expected input. Plan for miscommunication or incomplete requests by building robust error-handling mechanisms. Provide helpful feedback and re-prompt the user to clarify their request without being overly repetitive.

f) Contextual Awareness
Voice apps should be context-aware to enhance the user experience. For example, when a user asks for weather updates, the app should know the user’s location or ask for it in a seamless manner. Maintain context within a session to allow for follow-up questions.

3. Choosing the Right Voice Assistant Platform

Before starting development, it’s important to choose the right voice assistant platform for your app. The three most popular platforms include:

a) Amazon Alexa
– Strengths: Alexa Skills are widely adopted, with integrations across various smart home devices and Amazon’s ecosystem.
– Development Tool: Alexa Skills Kit (ASK)
– Best For: E-commerce, smart home control, and media applications.

b) Google Assistant
– Strengths: Google Assistant’s integration with the Google ecosystem (e.g., Google Search, Google Calendar) makes it particularly useful for productivity apps and services.
– Development Tool: Actions on Google, Dialogflow
– Best For: Search-based queries, navigation, and location-based services.

c) Apple Siri
– Strengths: Siri Shortcuts integrate well with Apple’s ecosystem, including iPhones, Apple Watch, and HomeKit devices.
– Development Tool: SiriKit, Shortcuts
– Best For: iOS-native apps and Apple device integration.

Choose a platform based on your target audience, the devices they use, and the functionality your app will provide. In some cases, developing for multiple platforms may be beneficial to reach a broader user base.

4. Key Best Practices for Building Voice Assistant Apps

To create a successful voice app, developers need to focus on both technical performance and user experience. Here are best practices to keep in mind:

a) Design for Conversational Flow
Your app should offer a smooth, intuitive conversational experience. Consider all potential user inputs and responses, and design clear conversational paths. Use branching dialogs and logical fallbacks to handle unexpected user responses.

b) Leverage Contextual Data
Voice assistants have access to a wealth of contextual information, such as location, time, and user preferences. Use this data to personalize interactions and offer relevant information based on the context of the conversation.

c) Optimize for Speed
Users expect immediate responses from voice assistants. Ensure that your voice app has minimal latency, as any delay in response can lead to user frustration. Optimize backend performance and reduce unnecessary processing to keep the interaction quick.

d) Support Multiple Input Modalities
In many cases, users will interact with voice apps on devices with screens (smartphones, smart displays). Design your app to take advantage of these screens by providing visual feedback (e.g., product images, maps, text-based prompts) when appropriate.

e) Prioritize Accessibility
Voice assistants are a crucial technology for users with disabilities. Ensure your voice app is accessible to all users by following guidelines that make your app usable for people with varying abilities, such as those with visual or physical impairments.

f) Continuous Learning and Improvement
Use data from user interactions to continuously improve your app. Track common queries, where users drop off, and which interactions require improvement. Use this information to update your app’s dialog flows and enhance user satisfaction.

g) Test on Multiple Devices
Voice assistants operate across a range of devices (smart speakers, smartphones, wearables). Test your app on different devices to ensure it performs consistently and optimally across various environments.

5. Tools and Frameworks for Developing Voice Apps

Here are some popular tools and frameworks that can help you develop voice apps:

a) Alexa Skills Kit (ASK)
Amazon’s Alexa Skills Kit allows developers to create voice-driven applications for Alexa. It includes pre-built templates, developer tools, and APIs to integrate with other AWS services.

b) Actions on Google
Google’s platform for developing voice apps, Actions on Google, integrates with Google Assistant and uses Dialogflow for natural language processing and intent matching.

c) Jovo Framework
Jovo is a popular open-source framework that allows developers to create cross-platform voice apps that work on both Amazon Alexa and Google Assistant. It simplifies development by offering a unified codebase.

d) SiriKit and Shortcuts
SiriKit allows developers to build apps that work with Siri by integrating app-specific features into the voice assistant. Shortcuts also enable automation for tasks users frequently perform with voice commands.

6. Testing and Optimizing Your Voice App

Before launching your voice app, testing is crucial to ensure smooth interactions and a bug-free user experience. Here are steps to follow:

a) Simulate Conversations
Use built-in testing tools like Alexa Developer Console or Dialogflow to simulate conversations and test different paths users might take. Ensure you cover all possible scenarios, including edge cases.

b) Test on Real Devices
Voice app behavior can vary between simulators and real devices. Test your app on the actual hardware your users will be using, such as smart speakers or smart displays, to identify any unexpected issues.

c) Monitor App Performance
Once your app is live, monitor key metrics like conversation completion rates, errors, and drop-offs. This will help you identify areas for improvement and make data-driven decisions for future updates.

7. Challenges in Voice App Development

While developing voice apps offers exciting possibilities, it comes with challenges:

– Limited Discoverability: Voice apps aren’t always easy to discover, unlike traditional mobile apps in app stores. Ensure your app has a clear invocation name and is promoted through relevant channels.
– Complex Dialog Management: Handling a variety of user inputs can be challenging. You’ll need robust NLP (Natural Language Processing) capabilities and fallback strategies for incomplete or ambiguous user commands.
– Privacy Concerns: Voice apps often require access to personal data (e.g., location, voice recordings). Ensure your app complies with privacy regulations and offers transparency about data collection.

8. Future Trends in Voice Assistant Apps

Voice technology is evolving rapidly, and several trends are shaping the future of voice app development:

– Multimodal Voice Apps: Voice assistants on devices with screens (smart displays, TVs) are increasingly popular. Voice apps that combine voice interaction with visual feedback will offer richer user experiences.
– Improved Natural Language Understanding: Advances in NLP and AI will allow voice assistants to understand more complex, multi-turn conversations, making voice apps more natural and intuitive.
– Voice Biometrics: Future voice apps may incorporate biometric authentication, enabling voice assistants to recognize and personalize experiences based on individual user voices.

9. Conclusion

Building voice assistant apps offers developers a unique opportunity to create hands-free, conversational experiences for users. By following best practices—such as designing natural conversational flows, leveraging contextual data, and optimizing for speed and performance—you can create voice apps that engage users and deliver meaningful value.

As voice technology continues to evolve, developers who prioritize usability, accessibility, and continuous improvement will be well-positioned to thrive in the rapidly growing voice app market.