OpenAI Codex CLI vs Anthropic Claude Code: A New Chapter in AI Coding Assistants

tl;dr

OpenAI and Anthropic released AI-powered terminal coding assistants: Codex CLI (OpenAI) and Claude Code (Anthropic). Both tools execute complex programming tasks using natural language directly from your terminal—writing, refactoring, debugging code, and managing version control.

Key Differences:

• Privacy: Codex CLI operates locally with no data collection unless explicitly shared. Claude Code collects usage data and interactions to refine its beta product.

• Licensing: Codex CLI is fully open-source under Apache-2.0, allowing community contribution and modification. Claude Code uses a restrictive Business Source License, preventing redistribution or integration into other projects.

• Strategic Goals: OpenAI aims to foster community trust and ecosystem growth, encouraging third-party integrations and plugins. Anthropic’s approach prioritizes controlled product evolution and leveraging user feedback.

• Integration Potential: Codex CLI’s openness allows future integration into popular IDEs (e.g., VS Code), challenging established AI coding tools like GitHub Copilot and Cursor. Claude Code remains more tightly controlled by Anthropic.

Both tools represent strategic moves to dominate the AI-assisted development market, reflecting differing philosophies on openness, community engagement, and data privacy. Developers gain powerful new tools and increased choice.

Full story

Imagine your terminal could understand your requests and write code for you – that's exactly what's unfolding with the latest AI coding tools. In the past week, OpenAI unveiled Codex CLI, a terminal-based AI coding agent, hot on the heels of Anthropic’s Claude Code release. Both promise to bring ChatGPT-style assistance into your local development workflow. Here’s a breakdown of how these two new copilots compare, and what their emergence means for developers and the industry.

Meet the Terminal Coding Assistants

Codex CLI and Claude Code share a mission: let developers use natural language to manipulate codebases and automate dev tasks right from the command line. Tell the agent to “find and fix a bug,” “explain this code,” or “generate a new module,” and watch it perform those actions within your local environment. Both can edit files, run tests, refactor code, and even handle version control tasks like creating commits – effectively acting as AI pair programmers in your terminal (Github - Claude Code). OpenAI’s Codex CLI was somewhat framed as their answer to Claude Code (Opinion - Simonwillison.net), meaning we now have two very similar tools from two AI rivals. Each integrates with powerful language models (OpenAI’s latest or Anthropic’s Claude) to understand your code and intentions. In short, Codex CLI and Claude Code are direct competitors, bringing “agentic” coding to your laptop.

Technical use case example

Imagine you’re onboarding to a large legacy project. Instead of combing through documentation, you could ask one of these agents, “Explain the architecture of this repository and identify potential dead code.” The AI would parse the codebase and give you a summary, pointing out unused modules or confusing areas. You might then say, “Okay, remove the dead code and update any references,” and the agent would edit the files accordingly, all under version control. This kind of workflow – high-level instructions turning into concrete code changes – is what both Codex CLI and Claude Code aim to enable. Notably, Codex CLI even supports multimodal input: you can pass it a screenshot or diagram to, say, help build a UI from a mockup (Report - TechCrunch). These tools blur the line between coding and conversing, making the terminal a smarter, more interactive place.

Privacy Matters: Local First vs. Data Collection

One immediate difference is how each tool handles your data and code. OpenAI’s Codex CLI is designed to run fully on your machine with a “minimal, transparent interface” (Article - TechCrunch). You use your own API key, and the code for the CLI is open – so there’s no hidden telemetry sending your usage data back to OpenAI. In fact, OpenAI emphasizes that your source code stays local by default: “Your source code never leaves your machine unless you explicitly share it. Privacy and security are paramount,” one early review noted (Opinion - dev.to). In practice, Codex CLI does of course send prompts to the OpenAI model (that’s how it works its magic), but OpenAI’s API policies state they don’t use API data for training by default. The key point is that Codex CLI itself isn’t siphoning up extra analytics about your coding sessions.

Contrast that with Claude Code: Anthropic’s tool requires you to log in with an Anthropic account, and it explicitly collects usage data during this beta period. According to Anthropic’s documentation, when you use Claude Code they gather feedback including “usage data (such as code acceptance or rejections), associated conversation data, and user feedback” (Github - Claude Code). This is part of Claude Code’s “research preview” approach – Anthropic is upfront that they’re learning from how developers use the tool. They store conversation transcripts for 30 days (for debugging) and promise not to train their models on your specific code or conversations (Github - Claude Code). Still, some developers might be uneasy knowing Claude Code is logging their interactions.

In short, Codex CLI feels more private – no sign-in, open-source code, and no mention of telemetry – whereas Claude Code phones home with your usage (albeit to improve the product, not to train AI on your code). Developers highly concerned with privacy may appreciate Codex’s local-first philosophy. Claude Code users, on the other hand, are effectively opting into Anthropic’s feedback loop (which for some is a fair trade if it leads to a better AI assistant). It’s a notable philosophical difference: OpenAI is giving you a tool and largely staying out of your way, while Anthropic is actively monitoring how you use their tool (in a limited, privacy-conscious manner) to refine it.

Open Source vs. Business Source: Licensing Differences

Another key distinction is the license and openness of the two projects. OpenAI released Codex CLI as open source – in fact, under a permissive license (Apache-2.0) that’s functionally similar to MIT (Github - Codex Licence). This means the entire codebase for the CLI tool is available on GitHub, free for anyone to inspect, modify, and contribute to. Developers can already file pull requests, suggest features, or fork it for their own needs. OpenAI explicitly invites the community to help build Codex CLI, even noting “it’s fully open-source so you can see and contribute to how it develops!” (Github - Codex). For developers, this openness inspires confidence – you can audit that it’s not doing anything shady with your data, and you can adapt the tool as needed. It also signals that OpenAI wants Codex CLI to become a community-driven project over time.

Anthropic’s Claude Code takes a very different approach. It’s released under a Business Source License (BUSL) – effectively a closed-source license. The source code is available to view (since developers have managed to read parts of it), but the license imposes significant restrictions on use and forbids unauthorized redistribution or commercial hosting. Anthropic’s own description highlights this: Claude Code’s closed license limits community contributions and customization (Opinion - dev.to). In other words, you can use Claude Code as provided (it’s free during the beta), but you can’t legally fork it or incorporate its code into your own projects. All rights remain reserved by Anthropic (Github - Claude Code Licence). This is a common strategy lately (many AI companies use BUSL or similar), balancing openness with business control: developers can try the tool, but the company retains exclusive rights to commercialize it.

The implications are significant. Codex CLI’s MIT/Apache license makes it easy to integrate into other tools or workflows – we might soon see community-made plugins, or someone could embed Codex CLI into different IDEs without legal hurdles. Claude Code, being proprietary, will evolve solely under Anthropic’s direction and cannot benefit from community fixes in the same way. From a trust standpoint, some devs simply prefer open source tools; OpenAI’s choice here may earn goodwill. On the flip side, Anthropic’s decision suggests they see Claude Code’s technology as a competitive asset to protect (perhaps reflecting confidence in Claude’s capabilities). It’s a stark open vs. closed split: OpenAI is betting on openness and community, while Anthropic is keeping tighter control over their solution.

Why Are These Tools Being Released? Strategic Motives

It’s no coincidence that both OpenAI and Anthropic are pushing AI coding assistants now. Strategically, these releases are about staking a claim in the developer toolchain and winning developer goodwill:

• Positioning in the AI Dev Ecosystem: Both companies want their AI to become the go-to assistant for programmers. By offering a command-line agent, they’re inserting themselves at a crucial point in the development workflow. If developers adopt Codex CLI or Claude Code early, those tools could become as indispensable as Git or VS Code in the long run. There’s a landgrab underway for the “AI coding assistant” space, and neither OpenAI nor Anthropic wants to cede ground to the other (or to third parties). As evidence of how high the stakes are, OpenAI is reportedly even in talks to acquire Windsurf (Codeium) – another AI coding tool – for $3 billion, which would put it head-to-head with other players like Cursor (Article - The Indian Express). Clearly, big bets are being placed on owning this layer of the software development process.

• Developer Goodwill and Feedback: OpenAI’s move to open source Codex CLI is likely an effort to curry favor with developers. The company has faced criticism in recent years for its closed-off approach, so releasing a useful tool under a free license is a goodwill gesture. It invites trust (“here’s our code, take a look”) and invites collaboration (“help us improve it”). They even launched a $1 million grant program to encourage devs to build on Codex CLI (Opinion - Slashdot.org), essentially seeding an ecosystem around their models. Anthropic, meanwhile, framed Claude Code explicitly as a research preview to learn from users: “We’re launching Claude Code in beta to learn directly from developers about their experiences... and how we can make the agent better,” the team said (Github - Claude Code). Anthropic is gathering feedback and iterating rapidly, which can engender goodwill if developers feel their input is shaping the product. However, one can also view Claude Code’s free beta as a way to showcase Claude’s strengths (coding is a known forte of Claude’s model) and attract users to Anthropic’s platform, without giving away the family jewels (the model or code).

• Competitive Response: It’s hard not to see these releases as responses to each other. Anthropic unveiled Claude Code (with Claude 3.7) to capitalize on its model’s coding prowess and perhaps to challenge the narrative that OpenAI’s GPT-4 was the only game in town for coding assistance. In turn, OpenAI releasing Codex CLI shortly after shows they’re not going to let Anthropic have that spotlight. Each company is ensuring it has an answer to the other’s offering. This competition benefits developers: we get to try multiple tools and watch them improve quickly as each firm races to one-up the other.

In essence, both OpenAI and Anthropic recognize that integrating AI into programming is the next big opportunity. By open-sourcing Codex CLI, OpenAI might be aiming to make it the foundational layer that others build upon, thus indirectly tying the community to OpenAI’s models. Anthropic’s strategy with Claude Code is more about showcasing capability and learning from real-world use (while keeping control). Different tactics, same goal: make their AI indispensable for developers.

The VS Code Question: A Glimpse into the Future

One exciting implication of Codex CLI’s openness is the possibility of integrations with popular IDEs. Today, Codex CLI runs in the terminal; tomorrow, we might see it (or components of it) in VS Code, JetBrains IDEs, or other developer tools. If Codex CLI were integrated into VS Code, for example, it could provide a ChatGPT-like coding experience directly in the editor – effectively bringing the fight to tools like Cursor or GitHub Copilot. In fact, several startups and projects (Cursor, Codeium/Windsurf, Amazon CodeWhisperer, etc.) are already in this space of AI-assisted coding in editors. OpenAI’s own partner, GitHub, has the Copilot extension and a beta “Copilot Chat.” An official VS Code integration of Codex CLI (or a community-built one, which the MIT license allows) would intensify competition. Developers would have an array of AI coding assistants to choose from: some open source, some proprietary, each tied to different AI models.

It’s worth noting how serious this competition is becoming. As mentioned, OpenAI’s rumored interest in acquiring Codeium (maker of Windsurf) for billions underscores that AI coding interfaces are strategic assets (Article - The Indian Express). The mention of Cursor as a rival (which OpenAI has also invested in) shows even partners can become competitors in this fast-moving space (Article - TechCrunch). If Codex CLI gains traction and community support, it could quickly evolve and integrate into GUI-based tools, potentially outpacing closed solutions. For example, one could imagine a future VS Code extension named “OpenAI Codex” that uses the Codex CLI backend – giving VS Code users a fully local, open source AI helper. That would directly challenge Cursor (an AI-enabled IDE) and even put pressure on GitHub Copilot by offering a more autonomous, agentic experience (Copilot is great for suggestions, but Codex CLI can execute commands and manage projects autonomously).

For developers, this means more choice and faster innovation. Codex CLI in an IDE could combine the best of both worlds: the convenience of in-editor assistance with the power of an agent that can run tests or refactor across files on its own. Meanwhile, Claude Code could also potentially be wrapped into an editor environment (Anthropic might release a plugin in the future, though the license could complicate third-party ones). In any case, the lines between “editor” and “terminal” workflows may blur – your IDE might have a console where an AI agent is conversing with you about your code and performing changes, whether powered by OpenAI or Anthropic. And because Codex CLI is open, anyone could build those bridges (there might even be a community project underway right now to hook Codex into VS Code).

OpenAI Open-Sourcing Again – Why It Matters

Beyond the head-to-head comparison, there’s a bigger narrative here: OpenAI embracing open source (at least in tooling) once more. The release of Codex CLI under a free license is significant – as Fortune pointed out, this is the first time since 2019 that OpenAI has introduced a major open-source tool (Article - Fortune). For context, early OpenAI projects and models were often open-sourced (e.g. OpenAI Gym, baselines, etc.), but as the company pivoted to powerful large models like GPT-3 and GPT-4, it became more closed and proprietary. Aside from smaller releases like Whisper (speech-to-text) and some libraries, OpenAI hasn’t really put out a big open-source project in years. Codex CLI breaks that pattern.

The significance is twofold. First, it’s a PR win and trust signal to the developer community. OpenAI is saying, “We’re not just an API SaaS company; we remember the value of open source.” By letting devs peek under the hood of Codex CLI, they engender trust: users can verify what the tool is doing. This is especially important for something that interacts with your filesystem and code – being able to audit it is reassuring. It may also win back favor with those who prefer open ecosystems; some devs were gravitating toward open-source LLM projects, and this move shows OpenAI can collaborate in the open too.

Second, open-sourcing the tool (though notably not the models behind it) could help OpenAI establish a standard. If Codex CLI (or its protocol for communicating with the model, handling file edits, etc.) becomes widely adopted, it could become the de facto interface for “AI agents in coding.” That would naturally funnel users towards OpenAI’s API/models (since Codex CLI is built for them). It’s a savvy way to cement OpenAI’s presence: give away the wrapper to attract users, while the core (the AI models like the new o3 or o4-mini) remains a paid service. It’s somewhat analogous to how some companies open-source a client or framework to drive adoption of a proprietary backend. Meanwhile, Anthropic’s strategy with Claude Code is the opposite – they are giving away limited use of their model via a closed tool. Time will tell which approach garners more developer loyalty.

From a broader industry perspective, OpenAI’s return to open source (even if just a tactical move) is encouraging. It shows that even the leaders in AI acknowledge the importance of community and transparency. If others follow suit, we could see a trend where more AI-powered developer tools are open-sourced, which would accelerate progress through community contributions. For developers, having an open-source option like Codex CLI means you’re not entirely locked into a vendor’s vision – you can tweak the tool or even repurpose it with a different model (Codex CLI is compatible with OpenAI’s API and even open routers, potentially allowing alternative models). It slightly shifts power toward the user.

Conclusion: A Friendly Rivalry to Watch

In sum, Codex CLI and Claude Code represent a new wave of AI coding assistants that work alongside us in our native dev environments. OpenAI’s offering leans into openness, community, and integration potential, while Anthropic’s emphasizes controlled evolution and direct learning from user interactions. Both are incredibly ambitious in what they allow developers to do – effectively converse with your codebase and automate coding tasks at a higher level.

It will be fascinating to see how they evolve. Will OpenAI’s open approach lead to a richer ecosystem of plugins and integrations? Will Anthropic’s head start in coding intelligence keep Claude Code one step ahead in capabilities? And might we eventually see these two not just in terminals, but baked into IDEs and cloud development platforms? One thing is certain: this rivalry is spurring rapid innovation. As a developer, that means more powerful tools at your disposal, and the freedom to choose one that aligns with your preferences (be it open vs closed, local vs cloud, etc.).

So, which AI coding companion would you prefer in your workflow – the open-source newcomer or the research preview veteran? Let me know your thoughts! 🚀💻

Sources: OpenAI & Anthropic official docs and announcements, TechCrunch/fortune coverage, and developer opinion pieces

(Github - Claude Code)

(Github - Codex)

(Opinion - dev.to)

(Opinion - Slashdot.org)

(Opinion - simonwillison.net)

(Article - Fortune)

(Article - TechCrunch)

(Article - The Indian Express)