Google is preparing to roll out its Gemini 4 Argon model to the public, while employees inside the company are already testing a newer internal version codenamed Carbon, according to documents and screenshots seen by Business Insider. The Carbon model was made available on Google's internal coding platform, Jetski, in recent days.
One employee told Business Insider that Carbon "feels like Opus 5.5" for coding, referring to Anthropic's most powerful model for long-term agentic coding, though they added they would need to test it further. Google declined to comment on the internal testing.
Gemini 4 Argon specs and internal testing
Google announced its Gemini 4 generation in late September, saying Argon delivered frontier performance on some coding and knowledge work benchmarks, including legal and finance domains, with a strong focus on defensive cybersecurity. The company said the model would first be available to partners in its Fairwind Program before a wider public rollout.
Internally, Google has tested a series of Gemini 4 models under the codenames Argon, Barium, and Carbon. One document noted that the internal "Barium-B" model was chosen to be the model that will be known publicly as Argon, reflecting how Google's internal codenames often differ from their public names.
Early versions of Argon tested internally were generally well received by staff, according to conversations with employees and internal message threads seen by Business Insider. However, one employee said early versions of Argon felt behind on some coding tasks, comparing the model to Claude Opus 5.
- Internal codenames tested: Argon, Barium, Carbon
- Carbon available on Google's internal coding platform Jetski
