OpenAI Counters Anthropic with the Release of GPT-5.3 Codex

OpenAI unveils GPT-5.3 Codex after Anthropic's Claude Opus 4.6 release.

OpenAI has unveiled the latest version of its programming AI model, GPT-5.3 Codex, shortly after the launch of Anthropic’s flagship neural network, Claude Opus 4.6.

GPT-5.3-Codex is now available in Codex.

You can just build things.https://t.co/dyBiIQXGx1

— OpenAI (@OpenAI) February 5, 2026

The company stated that the LLM transforms the newly launched Codex application from an “agent that can simply write and check code” into an assistant capable of “doing virtually everything developers and professionals can do on a computer.”

OpenAI tested the new neural network across various performance metrics and concluded that it can create “highly functional complex games and applications from scratch in a matter of days.”

GPT-5.3 Codex is 25% faster than version 5.2. It is the first in the company to have “played a significant role in creating itself.” Startup employees used early program modifications for debugging and performance evaluation.

OpenAI and Anthropic introduced new solutions almost simultaneously. Both companies had the same release date and time, but the latter subsequently moved its launch 15 minutes earlier.

New Corporate Platform

The releases did not end there. OpenAI launched a new corporate platform, Frontier, which “acts as an intelligent layer, integrating disparate systems and data within an organization.”

The product is designed to simplify for companies the management, deployment, and creation of AI agents capable of independently performing tasks.

“Frontier is an acknowledgment that we won’t create everything ourselves. It’s better to work with the ecosystem to create together with it,” commented OpenAI’s CEO of Applications, Fidji Simo.

Recently, the company has been actively expanding in the business client market. In November 2025, it reported surpassing the milestone of 1 million corporate users.

In January 2026, OpenAI’s CFO, Sarah Friar, reported that the B2B sector accounts for approximately 40% of the startup’s business.

The new platform complements existing business offerings like ChatGPT Enterprise.

Frontier provides agents with access to shared context within the client’s organization, connecting various internal applications and tools for work. This enables digital assistants to perform complex tasks and analyze data.

Back in January, a specialized version of the GPT-5 line for programming — GPT-5.2 Codex — became available in Cursor.