Silverlight to Blazor Migration Services
Compare Silverlight to Blazor partners. Real costs ($50K–$800K, $250K median), 8-month timelines, WebAssembly vs Server strategies. 4 vetted firms.
Key findings
Risk of inactionSilverlight applications are already non-functional in most browsers. Organizations still running Silverlight are forcing users onto legacy browsers (IE) or maintaining complex plugin workarounds. User experience and security continue degrading with no viable maintenance path.
On this page
- Why Blazor?
- Technical Deep Dive
- 1. The "WCF RIA Services" Problem
- 2. UI Rewrite: XAML to Razor
- 3. Blazor Hosting Models
- Migration Complexity by App Type
- The Hidden Benefit
- Architecture Transformation
- Post-Migration: Best Practices
- Months 1-3: Performance Tuning
- Months 4-6: Modernization
- Risk Factors
- Plugin vs. WebAssembly Performance Gap
- WCF RIA Services Dead End
- XAML Incompatibility
- Synchronous vs Asynchronous
- Feasibility Analysis
- Ideal candidates
Related
Why Blazor?
Silverlight was Microsoft's attempt to bring .NET to the browser via a plugin. It failed because the web moved to open standards (HTML5). Blazor WebAssembly fulfills the original promise of Silverlight: running C# in the browser, natively, without plugins.
Technical Deep Dive
1. The "WCF RIA Services" Problem
This is the biggest blocker. WCF RIA Services automagically handled validation, serialization, and CRUD operations.
- Migration: You must replace this with ASP.NET Core Web API.
- Tip: Use gRPC if you need high-performance, strongly-typed contracts between client and server, similar to the old WCF experience.
2. UI Rewrite: XAML to Razor
You cannot copy-paste XAML to Blazor.
- Silverlight:
<Button Content="Click Me" Click="Button_Click" /> - Blazor:
<button @onclick="Button_Click">Click Me</button> - Strategy: Don't just port the UI. Silverlight apps often look like Windows 98. Use this opportunity to implement a modern Design System (e.g., MudBlazor or Fluent UI).
3. Blazor Hosting Models
- Blazor WebAssembly (WASM): Runs entirely in the client browser. Best for offline support and low latency UI. Closest to Silverlight architecture.
- Blazor Server: Runs on the server, sends UI updates via SignalR. Best for apps with heavy proprietary algorithms you don't want to download to the client.
Migration Complexity by App Type
Simple Apps (Forms, CRUD):
- ✅ XAML → Razor conversion is straightforward
- ✅ MVVM patterns transfer directly
- ✅ Most migrations succeed in 3-6 months
Complex Apps (Charts, Real-time Data):
- ⚠️ Blazor's rendering performance is weaker than Silverlight
- ⚠️ Third-party chart libraries (Telerik, Syncfusion) are expensive
- ⚠️ Real-time SignalR can introduce latency
The Hidden Benefit
Blazor is great for internal enterprise apps because:
- ✅ No JavaScript fatigue (use C# for everything)
- ✅ .NET shops can reuse backend developers
- ✅ Strong tooling (Visual Studio, Rider)
Architecture Transformation
Post-Migration: Best Practices
Months 1-3: Performance Tuning
- WASM Size: Optimize the download size of the Blazor app (Tree Shaking).
- Lazy Loading: Load assemblies only when needed to speed up initial load.
Months 4-6: Modernization
- PWA: Turn the Blazor app into a Progressive Web App (PWA) for installability.
- Design System: Implement a consistent design language across all internal tools.
Risk Factors
Plugin vs. WebAssembly Performance Gap
Silverlight ran as a native plugin with near-native performance. Blazor WebAssembly is 3-10x slower for compute-intensive tasks (charts, grids, calculations). If your app relies on fast client-side processing, expect user complaints about lag.
WCF RIA Services Dead End
Silverlight apps heavily relied on WCF RIA Services for client-server communication. This technology is dead. You must rewrite the backend as a standard REST API (ASP.NET Core Web API) or gRPC service.
XAML Incompatibility
While both use XAML, Silverlight XAML and standard WPF/UWP XAML have subtle differences. Blazor doesn't use XAML at all (it uses Razor components). This means the UI layer is a 100% rewrite.
Synchronous vs Asynchronous
Silverlight forced asynchronous calls for network operations, but often in a callback style. Modern .NET uses async/await. Converting callback hell to clean async tasks is a major refactoring effort.
Feasibility Analysis
Ideal candidates
- App requires IE mode to run (Security risk)
- Team is already skilled in C#/.NET
- Rich client interactivity is required
Break-even cost: $50k Talent risk: Low. C# skills transfer perfectly to Blazor.
The numbers
Verified benchmarks for Silverlight to Blazor Migration Services, aggregated from analyzed projects. Figures are ranges, not point estimates.
Cost
Timeline
Success rate
Vendor pool
| Cost range | $50k – $800k |
|---|---|
| Median cost | $250k |
| Median timeline | 8 months |
| Success rate | 90% |
| Complexity | High |
| Typical ROI | 12–24 months |
| Projects analyzed | n=150 |
The business case
Typical ROI
12–24 months
Key drivers
- Silverlight is effectively broken — modern browsers block plugin execution entirely
- Blazor WebAssembly enables C# in the browser — preserves team's .NET investment
- Application becomes accessible on all devices (mobile, tablet) for the first time
- Eliminates IT support burden of managing Silverlight plugin compatibility workarounds
Should you migrate?
A decision framework for Silverlight to Blazor Migration Services — the conditions that favor migrating, the ones that argue against it, and the alternatives worth weighing first.
Migrate if
- Silverlight plugin is blocked by all major browsers (Chrome, Edge, Firefox, Safari)
- Application is inaccessible to users on modern browsers
- Silverlight end-of-life (October 2021) makes security patching impossible
- Team has C# expertise — Blazor WebAssembly/Server enables C# in the browser
Don't migrate if
- Team wants to exit the .NET/C# ecosystem entirely
- Application is too complex for Blazor's current state (e.g., complex canvas rendering)
Alternatives to consider
| Alternative | Why | Best for |
|---|---|---|
| Silverlight → React or Angular | JavaScript ecosystem — larger talent pool and component libraries than Blazor | Organizations without strong .NET/C# investment who want the largest frontend ecosystem |
| Silverlight → WPF (desktop-only) | Move to native Windows desktop if browser access isn't required | Internal enterprise tools that only need Windows desktop, not web access |
Recommended Partners
Microsoft stack modernization
Best for: Enterprise .NET upgrades
Enterprise-scale Microsoft stack modernization
Best for: Large corporate intranets
Automated conversion tools for Silverlight
Best for: Rapid, direct conversion
Microsoft partner with deep Blazor expertise
Best for: Strategic UX redesign alongside migration
Frequently Asked Questions
Why migrate from Silverlight to Blazor?
Silverlight is dead. Blazor WebAssembly allows you to run C# in the browser natively, preserving your team's .NET skills.
Is Blazor as fast as Silverlight?
Blazor WASM is slower than the Silverlight plugin for compute-heavy tasks, but Blazor Server offers comparable performance for internal apps.
Can we reuse our XAML?
No. XAML is not compatible with Blazor's Razor syntax. The UI must be rewritten, which is a great opportunity for a UX refresh.
Chief Analyst, Software Modernization Intelligence · 10+ years B2B market research
Last reviewed:
150 projects analyzed