OpenAI debuts GPT‑5-Codex, a version of GPT‑5 optimized for agentic coding in Codex and says it spends its “thinking” time more dynamically than previous models
If You Ask Nicely Frederic Lardinois / The New Stack : OpenAI Launches a New GPT-5 Model for Its Codex Coding Agent David Gewirtz / ZDNET : OpenAI has new agentic coding partner for you now: GPT-5-Codex X: @openai : Forget autocomplete — this is agent-complete. On Episode 6 of the OpenAI Podcast, @gdb and Codex lead Thibault Sottiaux join @andrewmayne to talk about the leap from code suggestions to coding agents, the launch of GPT-5-Codex, and where software development could be by 2030. [video] Sam Altman / @sama : the vibes on codex feel like the first few months of chatgpt. fun energy! Nathan Lambert / @natolambert : Word on the street was that Codex CLI was currently beating out claude code, and this was before the model update. Excited to try it out! Still figuring out my first use case for Codex the agent, but the CLI is much better now. Miles Brundage / @miles_brundage : Anecdotally, current* Claude Code is more prone to being like “Aha! I found the issue” (then not fixing anything) than current Codex. *sounds like there's a model update coming soon Ethan Mollick / @emollick : The problem with the fact that the AI labs are run by coders who think code is the most vital thing in the world, is that the labs keep developing supercool specialized tools for coding (Codex, Claude Code, Cursor, etc.) but every other form of work is stuck with generic chatbots Noam Brown / @polynoamial : GPT-5-Codex is 10x faster for the easiest queries, and will think 2x longer for the hardest queries that benefit most from more compute. [image] Nick Turley / @nickaturley : most important graph. codex keeps getting better! Nat Eliason / @nateliason : Wow the new Codex CLI is REALLY good. RIP Claude Code (at least for this week) Prinz / @deredleritt3r : OpenAI: - Zero reaction to nano-banana - Codex improvements every few days This is quite telling. Prinz / @deredleritt3r : You may have assumed that Codex is using a router to decide which queries warrant faster responses and which require more thinking. But no, there is no routing in this model(!). [image] Miles Brundage / @miles_brundage : Yeah feels like it is ~all or nothing at login, IIUC? “All” is definitely impressive though Finbarr / @finbarrtimbers : The only substantive complaint I have about Codex is that it just goes and applies the edits without asking me for permission. I really really really like Claude Code's “plan” “accept edits” and “ask for permission” modes. Is there an equivalent? Sam Altman / @sama : GPT-5-Codex already ~40% of traffic for codex! should be the majority some time today. Shawn Wang / @swyx : this is the most important chart on the new gpt-5-codex model We are just beginning to exploit the potential of good routing and variable thinking: Easy responses are now >15x faster, but for the hard stuff, 5-codex now thinks 102% more than 5. Same model, same paradigm, but bending the curve to fit the nonlinearity of coding problems and llm usecases. [image] @scaling01 : small upgrade for Codex it's better at coding, code refactoring, it's used a lot more by OpenAI employees internally and less bad comments [image] Tibo / @thsottiaux : With gpt-5-codex, some will feel that it's the best thing since sliced bread, some will see its quirks. Personally it is my favorite collaborator for coding, fast for small things, working hard when it matters and a solid jump in produced code quality. $ codex -m gpt-5-codex Sam Altman / @sama : GPT-5-Codex is here: a version of GPT-5 better at agentic coding. It is faster, smarter, and has new capabilities. Let us know what you think! The team has been absolutely cooking, very fun to watch. Mike / @systemsculpt : this is EXACTLY what I wanted to see from the new gpt-5-codex model. vibe coding is fun until it makes decisions for you that you then have to spend time cleaning up, wasting time/adding technical debt this questioning you see here is chef's kiss. ask me more often! yay! [image] Dan Shipper / @danshipper : BREAKING NEWS: OpenAI just launched a new coding model GPT-5 Codex. We've been testing it at @every for a few days and it is WILD: - It dynamically chooses “thinking” time—so it works for long periods on hard questions and returns instant answers for easy ones - It ran [video] Nathan Lambert / @natolambert : Most interesting part of the Codex improvements blog is explaining how the model uses reasoning effort more dynamically to not waste tokens and solve harder problems: “GPT‑5-Codex adapts how much time it spends thinking more dynamically based on the complexity of the task. The [image] Alex Volkov / @altryne : BREAKING: OpenAI introduces GPT-5-Codex, a further finetune of GPT-5 for Codex like tasks (coding, PR reviews etc) I've heard over 10 folks who're switching away from CC to Codex recently, and many of those are switching because of GPT-5. This will likely just add more folks! [image] Kyle Russell / @kylebrussell : “During testing, we've seen GPT‑5-Codex work independently for more than 7 hours at a time on large, complex tasks” Dan Shipper / @danshipper : two important things from @OpenAI's GPT-5 Codex launch today: - dynamic thinking time—they moved this pattern from ChatGPT to their coding model, it's going to be standard going forward. - local to web handoff—your agent should be with you with full context wherever you are. [image] Greg Brockman / @gdb : GPT-5-Codex — big improvement for long-running agentic tasks: @openai : We're releasing GPT-5-Codex — a version of GPT-5 further optimized for agentic coding in Codex. Available in the Codex CLI, IDE Extension, web, mobile, and for code reviews in Github. https://openai.com/... LinkedIn: Derrick Choi : 🚀 We just launched GPT-5-Codex. It's now default for cloud tasks and code review, and you can opt in for the CLI and IDE. … Alexander Embiricos : OpenAI Codex has been taking off! And today we're releasing a new model further optimized for agentic coding in Codex: GPT-5-Codex. … Forums: Hacker News : GPT‑5-Codex and upgrades to Codex r/OpenAI : r/programare : Upgrades to codex (gpt 5) r/ChatGPTPro : OpenAI releases GPT‑5-Codex: A version of GPT‑5 optimized for agentic coding in Codex
Context & Ripple Effects
Codex had already moved beyond a chat-only coding assistant with the open-source Codex CLI for local code and computer tasks, then gained optional web access as OpenAI broadened availability beyond its highest-tier users. GPT-5-Codex makes the model itself a product-specific layer in that expanding Codex surface.
The significance is less a new endpoint than a shift in optimization: OpenAI is tuning GPT-5 for agents that can allocate more effort to difficult coding work, across the CLI, IDE, web, mobile, and GitHub review workflows.
First-order effects
- Codex users get a GPT-5 variant tailored to agentic coding, with reported dynamic reasoning that is faster on simpler requests while allocating more compute to harder ones.
- OpenAI can offer a more consistent coding-agent experience across its Codex interfaces, including GitHub code review, rather than treating coding as a general-purpose model prompt.
Second-order effects
- Coding-agent rivals, including IDE-native products such as Cursor, face a clearer comparison point: not just code completion quality, but whether an agent can carry a task through multiple steps and environments.
- The expanded Codex surface makes workflow integration—terminal access, IDE use, web access, and review—more important to adoption; the earlier addition of optional internet access illustrates that capability is increasingly shaped by the tools around the model.
Third-order effects
- If this approach holds, coding-model competition will move toward specialized agents that vary inference effort by task difficulty, with speed, reliability on long tasks, and access controls becoming part of the product rather than benchmark details.
- Software development tools may increasingly consolidate around an agent connected to local development work across several interfaces, raising the strategic value of owning the work surface as well as the underlying model.
The trend: GPT-5-Codex is part of the shift from autocomplete-style assistants toward embedded agents that plan, use tools, and adapt their effort to complete software tasks.