OpenAI Unveils GPT-5.3 Codex: Next-Generation Agentic Coding Model Following Anthropic's Release

05.02.2026

On Monday, OpenAI introduced Codex, an agentic coding tool specifically designed for software developers. In a rapid follow-up, the company has now released GPT-5.3 Codex, a next-generation model engineered to significantly enhance Codex's capabilities.

According to OpenAI, the new model elevates Codex from an agent capable of basic code writing and review to a comprehensive development assistant that can perform "nearly anything developers and professionals do on a computer." This advancement aims to democratize software development and transform traditional workflows.

Key Performance Improvements:

• The model demonstrates capability to autonomously create highly functional, complex games and applications from scratch over multi-day development cycles
• Performance benchmarks show a 25 percent speed increase compared to its predecessor, GPT-5.2
• Represents OpenAI's first self-improving model, with engineering teams utilizing early versions to debug and evaluate the system's own performance

The release timing is particularly noteworthy, as it follows immediately after competitor Anthropic launched its own agentic coding model. Both companies had initially coordinated to release their respective solutions simultaneously at 10 a.m. PST. However, Anthropic adjusted its release schedule, moving the announcement forward by 15 minutes to gain a slight competitive advantage in the market.

This rapid succession of releases underscores the intensifying competition in the AI-powered development tools sector, with major players racing to deliver increasingly sophisticated autonomous coding capabilities.

Sources:
OpenAI - Introducing GPT-5.3 Codex

Tags: OpenAI AI development Codex Agentic AI GPT-5.3

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