Is it worth migrating an existing .NET project to System.Text.Json?

Migrating to System.Text.Json is worth it for new .NET 6+ projects but requires careful evaluation for existing codebases. Benefits include significantly better performance (2-3x faster), lower memory usage, and future .NET alignment. Projects with high-throughput APIs or microservices gain measurable improvements. However, migration effort depends on Newtonsoft.Json feature usage. Simple POCO serialization migrates easily. Complex scenarios using custom converters, reference handling, or DataSet require significant rework. Calculate ROI: performance gains versus migration time. For legacy applications working fine, migration may not justify effort unless performance is critical. Greenfield projects should always use System.Text.Json. Hybrid approach works: use System.Text.Json for new code while keeping Newtonsoft.Json for legacy. Test migrated code thoroughly as behavior differences exist. Validate your JSON structures with our JSON Formatter at jsonconsole.com/json-formatter during migration. Prioritize high-traffic endpoints for migration first to maximize impact. Modern .NET applications benefit significantly from System.Text.Json.