1d ago

Stanford NLP's Aryaman Arora disputes Greg Brockman's claim that Codex is open source, pointing to its proprietary underlying model

Brockman cited a terminal-based coding agent repository as evidence.

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Original post

under appreciated that codex is open source

7:56 PM · May 23, 2026 View on X

codex is open source in the same way google search is open source (i can hit view source on the frontend)

Greg BrockmanGreg Brockman@gdb

under appreciated that codex is open source

2:56 AM · May 24, 2026 · 565.8K Views
7:38 PM · May 24, 2026 · 170.7K Views

@theo i don’t have any issue, i’m very glad for my friends there to be making a ton of money.

“Codex” as a name is ambiguous enough as you have pointed out that it’s very silly to claim the veneer over the model that they have released makes Codex open source in any meaningful sense

Theo - t3.ggTheo - t3.gg@theo

Terrible analogy. The codex CLI and app server are fully open source, Apache licensed and available on GitHub. The Codex desktop app is not (this frustrates me) Models labeled Codex are not open weight, which appears to be your issue here? Weird hill to die on. Conclusion: they used the name “codex” too much and this post is dumb

2:49 AM · May 25, 2026 · 24.6K Views
3:02 AM · May 25, 2026 · 4.7K Views

@theo yes great. I am simply saying the harness being open source is such a silly basis for the sentence Codex is open source. the thing that makes Codex work is not open source.

Theo - t3.ggTheo - t3.gg@theo

@aryaman2020 Codex the model exists because they wanted better models for codex the cli/harness, which is open source. Grill them for overusing the name all you want. I can destroy your awful analogy with one link: https://github.com/openai/codex

3:05 AM · May 25, 2026 · 2.6K Views
3:09 AM · May 25, 2026 · 1.4K Views

@theo it’s of course very reasonable for them to do that, it’s just funny that that is what open source has come to mean now.

Aryaman AroraAryaman Arora@aryaman2020

@theo yes great. I am simply saying the harness being open source is such a silly basis for the sentence Codex is open source. the thing that makes Codex work is not open source.

3:09 AM · May 25, 2026 · 1.4K Views
3:09 AM · May 25, 2026 · 1.2K Views

@aryaman2020 bad comparison

Aryaman AroraAryaman Arora@aryaman2020

codex is open source in the same way google search is open source (i can hit view source on the frontend)

7:38 PM · May 24, 2026 · 170.7K Views
8:11 PM · May 24, 2026 · 3.6K Views

Terrible analogy.

The codex CLI and app server are fully open source, Apache licensed and available on GitHub.

The Codex desktop app is not (this frustrates me)

Models labeled Codex are not open weight, which appears to be your issue here? Weird hill to die on.

Conclusion: they used the name “codex” too much and this post is dumb

Aryaman AroraAryaman Arora@aryaman2020

codex is open source in the same way google search is open source (i can hit view source on the frontend)

7:38 PM · May 24, 2026 · 170.7K Views
2:49 AM · May 25, 2026 · 24.6K Views

@aryaman2020 Codex the model exists because they wanted better models for codex the cli/harness, which is open source.

Grill them for overusing the name all you want. I can destroy your awful analogy with one link:

github.com
GitHub - openai/codex: Lightweight coding agent that runs in your terminal
Lightweight coding agent that runs in your terminal - openai/codex
Aryaman AroraAryaman Arora@aryaman2020

@theo i don’t have any issue, i’m very glad for my friends there to be making a ton of money. “Codex” as a name is ambiguous enough as you have pointed out that it’s very silly to claim the veneer over the model that they have released makes Codex open source in any meaningful sense

3:02 AM · May 25, 2026 · 4.7K Views
3:05 AM · May 25, 2026 · 2.6K Views

Codex is Open Source and you can learn a great deal about it just by pointing your codex to it

ask it how a feature X works, ask it how you can efficiently optimise your current setup

and perhaps my fav is seeing how team members building codex use codex

7:25 AM · May 24, 2026 · 45.5K Views
Vaibhav (VB) SrivastavVaibhav (VB) Srivastav@reach_vb

Codex is Open Source and you can learn a great deal about it just by pointing your codex to it ask it how a feature X works, ask it how you can efficiently optimise your current setup and perhaps my fav is seeing how team members building codex use codex

7:25 AM · May 24, 2026 · 45.5K Views
7:37 AM · May 24, 2026 · 2.4K Views