Gemma 4 31B is the largest dense model in Google's Apache 2.0 open-weights Gemma 4 family, released April 2026. It ships alongside the 26B A4B mixture-of-experts model, takes text and images, and has an optional thinking mode.
Pick it if
want Apache 2.0 open weights you can also self-host
need image input and a thinking mode at a low flat rate
write long outputs, since output costs the same as input
Skip it if
you need audio input; Google limits it to smaller Gemma 4 sizes
you rely on cached-prompt discounts to cut repeat-context cost
GPT-OSS 120B is the larger of OpenAI's two Apache 2.0 open-weight models, with 117B total and 5.1B active parameters. It takes text only and sits above the cheaper GPT-OSS 20B.
Pick it if
you want Apache 2.0 open weights you could also self-host
you need adjustable reasoning effort: low, medium or high
you need function calling and structured outputs from an open model
Skip it if
you need image input; it takes text only
you are on the free plan, which includes only the 20B sibling
FAQ
Which is cheaper, Gemma 4 31B or GPT-OSS 120B?
Gemma 4 31B lists lower input and output prices. On a coding-agent session (2M tokens in, 60,000 out) Gemma 4 31B costs $0.41 and GPT-OSS 120B $0.75.
Which one accepts images?
Gemma 4 31B supports vision; GPT-OSS 120B does not.
Can I switch between Gemma 4 31B and GPT-OSS 120B mid-task?
Yes. In an Octomind session, /model octohub:gemma-4-31b and /model octohub:gpt-oss-120b switch models without losing the conversation, so you can draft on one and review on the other.
Try either model
Switch between models inside the same Octomind session.