In the battle between two “agentic” coding tools — Anthropic’s Claude Code and OpenAI’s Codex CLI — the latter appears to be fostering more developer goodwill than the former. That’s at least partly because Anthropic has issued takedown notices to a developer trying to reverse-engineer Claude Code, which is under a more restrictive usage license than Codex CLI.
Claude Code and Codex CLI are dueling tools that accomplish much of the same thing: allow developers to tap into the power of AI models running in the cloud to complete various coding tasks. Anthropic and OpenAI released them within months of each other — each company racing to capture valuable developer mindshare.
The source code for Codex CLI is available under an Apache 2.0 license that allows for distribution and commercial use. That’s in contrast to Claude Code, which is tied to Anthropic’s commercial license. That limits how it can be modified without explicit permission from the company.
Anthropic also “obfuscated” the source code for Claude Code. In other words, Claude Code’s source code isn’t readily available. When a developer de-obfuscated it and released the source code on GitHub, Anthropic filed a DMCA complaint — a copyright notification requesting the code’s removal.
Developers on social media weren’t pleased by the move, which they said compared unfavorably with OpenAI’s rollout of Codex CLI. In the week or so since Codex CLI’s release, OpenAI has merged dozens of developer suggestions into the tool’s codebase, including one that lets Codex CLI tap AI models from rival providers — including Anthropic.
Anthropic didn’t respond to a request for comment. To be fair to the lab, Claude Code is still in beta (and a bit buggy); it’s possible Anthropic will release the source code under a permissive license in the future. Companies have many reasons for obfuscating code, security considerations being one of them.
It’s a somewhat surprising PR win for OpenAI, which in recent months has shied away from open source releases in favor of proprietary, locked-down products. It may be emblematic of a broader shift in the lab’s approach; OpenAI CEO Sam Altman earlier this year said he believed that the company has been on the “wrong side of history” when it comes to open source.
This article originally appeared on TechCrunch at https://techcrunch.com/2025/04/25/anthropic-sent-a-takedown-notice-to-a-dev-trying-to-reverse-engineer-its-coding-tool/
