GPT-5.4 Release: Thinking and Pro in ChatGPT, API and Codex

Melvin Vivas · X post · 2026-03-06 · Open on X

Topics: Industry Trends & Job Market, LLM Fundamentals · Level: beginner

Summary

Announcement that OpenAI's GPT-5.4 Thinking and GPT-5.4 Pro are rolling out in ChatGPT, and GPT-5.4 is also in the API and Codex. OpenAI says it combines its advances in reasoning, coding and agentic workflows in one frontier model.

Key points

• GPT-5.4 comes in Thinking and Pro variants in ChatGPT.
• It is available in the OpenAI API and in Codex.
• It is positioned as one model for reasoning, coding and agentic workflows.

Resources mentioned

• GPT-5.4 · tool · openai.com · paid
  OpenAI frontier model (Thinking and Pro variants) for reasoning, coding and agents.
  Also in: Opinion: GPT-5.4 in Cursor 3 Replaces Opus for Coding (Melvin Vivas on X · notes), Splitting AI Tools: Cursor 3 + GPT-5.4 for Code, Claude for Learning (Melvin Vivas on X · notes), Creator's Coding Setup: Cursor 3 with GPT 5.4 (Melvin Vivas on X · notes), Open-Source GLM-5.1 Beats GPT-5.4 on SWE-Bench Pro (Melvin Vivas on X · notes) and 2 more
• ChatGPT · tool · chatgpt.com · free · recommended by both Bashiri Smith & Melvin Vivas
  OpenAI's AI assistant (web, desktop and mobile apps), used for chat, coding, writing and image generation.
  Also in: Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Dots Demo: A Voice AI Agent Handling Travel Booking and Feedback Triage (Melvin Vivas on X · notes), ChatGPT Can Commit Code Directly to Your GitHub Repo (Melvin Vivas on X · notes), OpenAI Dots: Agents Inside ChatGPT That Debug, Fix, and Open PRs (Melvin Vivas on X · notes) and 23 more
• OpenAI API · tool · platform.openai.com · paid · recommended by both Bashiri Smith & Melvin Vivas
  OpenAI API documentation, including function calling and structured outputs.
  Also in: How to Relearn LLMs & RAG in 2026: A 7-Step Roadmap with Free Resources (Bashiri Smith on Facebook · notes), Livestream: Building a React Native ChatGPT App with Cursor and OpenAI (Melvin Vivas on X · notes), GPT-Live-1: OpenAI's Full-Duplex Voice Model for Voice Agents in the API (Melvin Vivas on X · notes), The 3 Levels of AI Engineering: LLM Apps → Production → Agentic Systems (Bashiri Smith on Facebook · notes) and 4 more
• OpenAI Codex · tool · openai.com · paid
  OpenAI's coding agent. In the diagram it writes code, fixes review findings and drives the build loop. The creator also used it to make this video.
  Also in: An agent bot that installs and drives Codex on its own (Melvin Vivas on X · notes), Asking a Coder bot to install Codex (Melvin Vivas on X · notes), Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Codex Cloud Environments Must Be Saved & Published Before Use (Melvin Vivas on X · notes) and 240 more

Try this

• Try GPT-5.4 through the API or Codex on your coding and agent tasks.