A comparison of using Codex 5.3 vs 5.2 for .NET development with Uno Platform

We Are .NET

A hands-on comparison of GPT-5.3-Codex vs GPT-5.2-Codex for .NET cross-platform development using Uno Platform. Both models were tasked with building a car dashboard UI from the same prompts, using Uno Platform MCP tools for code generation and verification. Codex 5.3 completed the task ~43% faster (~20 min vs ~35 min) and showed better data binding accuracy, while Codex 5.2 demonstrated deeper reasoning and bolder creative approaches like using real maps. Benchmark data shows Codex 5.3 is ~25% faster with major gains in terminal and OS task benchmarks, though SWE-Bench coding scores are nearly identical. Both produced fully functional cross-platform apps.

Codex 5.3 vs 5.2 for .NET Developers