Android Instant Apps 101: What They Are and How They Work

Since their introduction at Google I/O 2016, Android Instant Apps have promised to revolutionize how users discover and engage with apps by allowing them to launch apps instantly from web links, without needing to install them first. While still not ubiquitous, Instant Apps are seeing growing adoption and may hint at the future of app distribution and interaction.

As an Android developer, understanding Instant Apps is increasingly essential. In this comprehensive guide, we‘ll dive deep into the technical underpinnings of Instant Apps, their benefits and challenges, and how to get started building them.

What Are Android Instant Apps?

An Android Instant App is essentially a lightweight, modularized version of an Android app that can be downloaded and launched almost instantly when a user taps on an associated web link. The user gets to immediately engage with a native app experience without having to first install the full app from the Play Store.

This contrasts with the traditional app discovery and installation flow, where users must find an app in the Play Store, download the full APK, and install it before launching – a process that can take a minute or more even on fast connections, with a significant drop-off rate at each step.

Instant Apps also differ from Progressive Web Apps (PWAs), which are web apps that can be "installed" to a device home screen and offer some offline capabilities, but are still fundamentally web-based. Instant Apps, in contrast, are fully native Android apps, just served in smaller pieces.

The key innovation of Instant Apps is to leverage web links as a seamless gateway into native app experiences, bypassing the usual friction of app installation. A user can go from tapping on a URL in a web browser or messaging app to engaging with a high-quality native app experience in a matter of seconds.

How Instant Apps Work

Under the hood, Instant Apps work by splitting an app into multiple modules and downloading only the modules needed for a specific entry point on-demand, rather than installing the entire monolithic app.

The key components that enable Instant Apps include:

Android App Bundles and Dynamic Feature Modules

Introduced in 2018, the Android App Bundle is a new publishing format that allows apps to be split into multiple modules and delivered more efficiently. A base APK contains core app functionality and resources, while separate dynamic feature modules contain code and resources for specific features that can be downloaded on-demand.

Instant Apps make heavy use of dynamic feature modules, with each user flow or entry point contained in its own module that can be downloaded independently from the base app.

Modularizing App Logic and Navigation

To support Instant Apps, developers must modularize their app logic and navigation to determine which modules are required for different entry points. This involves defining clear interfaces and dependencies between modules and ensuring core functionality is contained in the base module.

Instant Apps use a single Activity as an entry point for each module, rather than allowing multiple Activities to be chained together. This keeps each Instant App module focused and lightweight.

App Links and Intent Filters

App Links are HTTP URLs that act as entry points into specific parts of an Android app. By defining Intent Filters in an app‘s manifest file, developers can specify which URLs should open which parts of their app.

Instant Apps use App Links to determine which dynamic feature module(s) to download when a URL is tapped. The App Links must be verified to prove ownership of the associated domain.

Instant-Enabled App Bundles

To publish an app with Instant App functionality, developers must first build an instant-enabled App Bundle that specifies which feature modules should be instant-enabled. The App Bundle is then uploaded to the Play Store with the instant-enabled option selected.

When a user taps on an instant-enabled App Link, Google Play instantly delivers the necessary feature modules (up to 4MB each) along with the base module to launch the Instant App. If the full app is already installed, the deep link simply opens in the installed app as usual.

Benefits and Impact

The potential benefits of Android Instant Apps are significant for both users and developers:

• Frictionless discovery and conversion: Instant Apps dramatically lower the barriers to trying a new app. In a Google-commissioned study of Instant Apps, 27% of users who clicked "Try Now" on an Instant App detail page in the Play Store went on to download the full app, compared to only 4% who clicked "Install". Users do not have to decide if an app is worth the time and space to download in full.

• Improved retention and engagement: By allowing users to re-engage with apps through web links without needing to have them installed, Instant Apps can help boost retention and re-engagement rates. Vimeo reported a 130% increase in session duration after launching an Instant App.

• Streamlined user flows: Instant Apps can provide a superior user experience for flows like registration, login, and checkout by keeping users in a focused native environment instead of bouncing between web pages and apps. Early adopters like Hollar have seen significantly higher conversion rates for Instant App users.

• App Preview Cards on Google Search and the Play Store. Developers can expose Try Now buttons and preview cards for their Instant Apps right on Google Search results and the Play Store, giving potential users a frictionless way to test-drive their app‘s experience from a search result or app listing.

However, the impact of Instant Apps so far has been limited by their relatively low adoption and some notable drawbacks:

• Increased development complexity: Supporting Instant Apps requires significant changes to app architecture and navigation, adding complexity to the development and QA process. Features implemented in an Instant App often need to be duplicated in the main app to ensure parity.

• Limited functionality: With a 4MB payload limit for feature modules and only a subset of Android permissions and features available to Instant Apps, many types of apps and features are simply not feasible as Instant Apps. Apps that depend heavily on background services, device storage, or restricted permissions often can‘t offer a compelling Instant App experience.

Current Adoption and Notable Examples

As of 2021, Android Instant Apps have seen modest but growing adoption among Android developers. At Google I/O 2019, Google reported that over 50% of the top global developers were building Instant App experiences. Some notable examples include:

• The NYTimes Crossword app lets users play the daily mini crossword puzzle instantly from a link without installing the app. This simple, focused experience is well-suited to Instant Apps and has significantly increased engagement.

• Onefootball‘s Instant App lets users check live soccer scores, stats, and news for specific teams or matches from links shared on social media or messaging apps. The focused nature of sports content aligns well with modular Instant App experiences.

• Ticketmaster‘s Instant App allows users to quickly purchase event tickets from links without having the app installed. The Instant App supports ticket selection and purchase flows with Google Pay integration.

• Realtor.com‘s Instant App allows users to search for and view detailed property listings from links without needing to download their full app first. The Instant App experience also supports scheduling visits and contacting agents.

Adoption Challenges and Future Outlook

Despite their benefits, Android Instant Apps face some notable hurdles to widespread adoption:

1. Technical complexity and unfamiliarity. Developing Instant Apps requires significant changes to app architecture and navigation, introducing complexity that many teams are not equipped to handle. There is also still limited knowledge and best practices around Instant App development.

2. Limited functionality. The constraints inherent to Instant Apps limit their applicability for apps that rely on larger codebases, heavier media assets, or restricted permissions. Developers must carefully scope their Instant App use cases to lightweight, focused flows.

3. Discoverability challenges. While Google has boosted Instant Apps‘ visibility through features like "Try Now" buttons on the Play Store, in practice users still have limited awareness and understanding of what Instant Apps are and when they‘re available as an option.

4. Cannibalization concerns. Some developers worry that Instant App usage could cannibalize full app installs if users feel their needs are met by the Instant App and see no reason to install the full app.

Looking ahead, Android Instant Apps have the potential to significantly shape the future of app distribution and discovery, but reaching that future will require ongoing investment and evolution.

Google continues to extend Instant Apps‘ capabilities and visibility, such as introducing support for Android App Bundles in 2020 to allow users to launch Instant experiences for apps that are not installed from links within installed apps.

Making Instant Apps viable for a broader range of apps and use cases will require continued enhancements to the size limits and functionality constraints. But perhaps more importantly, realizing Instant Apps‘ full potential will require a broader ecosystem and culture shift around how users discover and adopt apps.

As the lines between apps and the web continue to blur, Instant Apps point towards a future where the two are more fluidly intertwined – where apps are not a monolithic binary to be downloaded once, but a collection of lightweight, instant experiences that can be progressively expanded as needed. How quickly that future arrives remains to be seen, but Instant Apps will no doubt play a key role in shaping it.