All models
Google: Gemini 4 Flash
Coming soonProvisional ID
The rumored fast, low-cost tier of Google's Gemini 4 family, reportedly codenamed Hydrogen. Google hasn't announced it. If it ships and lands on APITokenRouter, your key works as is: just switch the model ID. Use Gemini 3.8 Flash or Gemini 4 Argon today.
Status
Coming soon (unconfirmed)
Official price (in / out)
Not announced
Context
Not announced
Released
Not announced
What we know
- Google hasn't announced Gemini 4 Flash. The name, model ID, date and price are all unconfirmed.
- Leak, not confirmed: on October 27, X user Pankaj Kumar wrote that Gemini 4 Flash is in internal testing under the codename "Hydrogen".
- In August, a news report said the string gemini-4-flash-preview had appeared in tokenizer code in Google's public SDK repository. Google hasn't published that model ID.
- So far Google has shipped Gemini 4 Argon to developers and announced Gemini 4 Carbon, which is open only to a group of cyber defenders.
Until it's out, use these two
Same key, just switch the model ID.
Gemini 3.8 Flash
gemini-3.8-flash
Google's current Flash model: fast and low-cost, for everyday tasks.
Background and sources
- Flash is Google's faster, cheaper tier. The current one is Gemini 3.8 Flash, generally available since September 2, 2026.
Sources
- Pankaj Kumar (@pankajkumar_dev) on X: "Gemini 4 Flash leaks: codenamed Hydrogen", unconfirmed (Oct 27, 2026)
- OfficeChai: Google preparing to release a Flash model named Gemini 4 Hydrogen, X users say (Nov 5, 2026)
- Nokiapoweruser: Google SDK leak reveals gemini-4-flash-preview reference (Aug 9, 2026)
- Gemini API docs: models
- Google blog: Introducing Gemini 4 Carbon (Oct 28, 2026)
Full write-up: Gemini 4 Flash