In 2021, Xamarin was the stronger fit for teams already working in C#/.NET and Visual Studio; React Native suited teams with React or JavaScript skills that valued its open-source ecosystem and cross-platform iteration. Neither was universally faster or better: the right choice depended on the team, app workload, native API needs and release constraints. There is an important update for anyone deciding today: Microsoft ended Xamarin support on May 1, 2024, so a new project in 2026 should not start on Xamarin.
What was the difference between Xamarin and React Native in 2021?
The main distinction was how each framework connected shared code to a mobile app. Xamarin let developers write shared business logic in C# while using native controls for the platform UI. React Native let developers build interfaces with React components backed by native platform implementations, with an architecture that was still evolving in 2021.
That distinction affected more than code reuse. A .NET team could stay close to its existing language and Microsoft tooling with Xamarin. A React team could apply familiar JavaScript and open-source workflows with React Native. Both could require platform-specific code, and neither eliminated the need to account for Android and iOS differences.
How did Xamarin and React Native compare?
| Decision point | Xamarin in 2021 | React Native in 2021 |
|---|---|---|
| Primary language | C#/.NET | JavaScript with React |
| UI approach | Native controls, with business logic shared across platforms | React components backed by native platform implementations |
| Natural team fit | Teams using .NET, C#, Visual Studio and Microsoft services | Teams using React or JavaScript, web-oriented tooling and open-source workflows |
| Code reuse | Microsoft Docs said “In most cases, 80% of application code is sharable.” — Microsoft Docs, 2020 | Cross-platform reuse was a core approach, with native modules or platform-specific code needed where app requirements called for them |
| Performance considerations | Native platform integration supported a near-native approach, but actual results depended on the workload | Native rendering and ongoing architecture work were part of the performance approach; results depended on workload and bridge or native-module choices |
| Platform scope described in 2021 | Android, iOS, macOS and Windows in Microsoft’s product description; iOS deployment required a macOS machine | Mobile, with Windows and macOS expansion also being advanced |
| Ecosystem direction | Microsoft/.NET integration and Visual Studio workflow | Open-source ecosystem and active architecture and release investment |
Which was better for a C# team?
For a team with substantial C#/.NET experience, Xamarin was the more natural 2021 choice. It allowed that team to use Visual Studio and its Microsoft-centered workflow, share business logic and retain native platform UI. Microsoft’s 80% figure was a general statement about how much application code could be shared in most cases, not a promise that every app would reach that level.
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That sharing boundary matters. Business rules and other platform-independent code are better candidates for reuse than behavior tied to a particular operating system, device API or native interface. Teams should estimate their own shareable code rather than treating a framework’s general guidance as a project forecast.
When was React Native the better fit?
React Native made more sense for a 2021 team with React or JavaScript skills, especially if it valued an open-source ecosystem and rapid cross-platform iteration. Meta’s H2 2021 update called that ecosystem one of React Native’s greatest strengths and described work on more predictable releases.
React Native was also pursuing wider platform reach. The 2021 update described a partnership with Microsoft to advance React Native on Windows and macOS. That was an expansion effort, not evidence that every app or feature had identical support across mobile, Windows and macOS.
Was React Native faster than Xamarin?
There is no supported universal answer. The authoritative sources cited here do not establish a head-to-head speed, startup-time or app-size winner. Microsoft’s general cross-platform guidance cautions that cross-platform frameworks can offer solid functionality and a native-like look and feel while still falling short of a fully native implementation in performance.
React Native’s architecture work is relevant, but it should not be mistaken for a universal benchmark. Its renderer documentation says Fabric development began in 2018 and that React Native in the Facebook app was backed by the new renderer in 2021. The architecture reduced serialization between JavaScript and the host platform and could prioritize high-priority interactions. Those are mechanisms and intended benefits, not proof that every React Native app outperformed Xamarin.
Meta reported that more than 1,000 surfaces in the Facebook app had been migrated to React Native’s new architecture in 2021. That figure describes Facebook’s migration, not the number of apps using the architecture or a performance result applicable to other projects.
For a real comparison, test the app’s own startup, scrolling, animation, memory use and native-module behavior on the target devices. Include the cost of implementing or waiting for support for native APIs that the framework or its packages do not yet expose.
What should teams weigh beyond language and speed?
- Native APIs: List the platform features the app needs, then determine whether the framework and its available modules support them. If not, account for the work to write and maintain native code.
- Tooling and debugging: Consider which IDE, language tools and debugging workflow the team already knows. In 2021, Xamarin aligned with Visual Studio and .NET; React Native aligned with React and JavaScript workflows.
- Release constraints: Check how framework releases and platform updates fit the app’s schedule. A dependency on a new platform capability can make release timing as important as code reuse.
- Team and hiring: Evaluate skills already on staff and the expertise the project can realistically hire or maintain. A framework’s technical strengths do not compensate for a team that cannot support it effectively.
- Actual app workload: Identify performance-sensitive interactions and validate them with representative devices and data. Do not choose based on an unqualified claim that one cross-platform framework is always faster.
What changed after 2021?
Microsoft’s support policy says support for all Xamarin SDKs, including Xamarin.Forms, ended on May 1, 2024. Microsoft says Xamarin.Forms evolved into .NET MAUI and recommends migrating existing Xamarin.Forms projects to .NET MAUI. That lifecycle change does not make Xamarin an irrational choice in a 2021 comparison, but it does change the answer for a new project now: do not begin one on unsupported Xamarin SDKs.
React Native’s 2021 architecture rollout was staged, and Meta reported that its new architecture had reached all React Native mobile products in the Facebook app by that update. That is a dated account of Meta’s own products, not a guarantee about the current state of every React Native app or platform target.
Quick Recap
How to choose between them in the 2021 context
- Choose Xamarin if the project was greenfield in 2021, the team was already invested in C#/.NET and Visual Studio, and shared business logic with native platform UI matched the app’s needs.
- Choose React Native if the team had React or JavaScript expertise, prioritized open-source ecosystem breadth and cross-platform iteration, or valued the Windows/macOS expansion underway at the time.
- Test before committing if the app depended heavily on cutting-edge platform APIs or had strict performance requirements. Compare the required native-module work and measure the actual app rather than assuming a framework-wide winner.
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