What is the difference between Gemini 3 Flash Preview and Grok 4 Fast (free)?

Gemini 3 Flash Preview is developed by Google AI while Grok 4 Fast (free) is developed by xAI. Gemini 3 Flash Preview has a 1.0M token context window vs Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 35 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3 Flash Preview or Grok 4 Fast (free)?

It depends on your use case. Gemini 3 Flash Preview and Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 35 challenges so you can judge which fits your needs best.

How much does Gemini 3 Flash Preview cost compared to Grok 4 Fast (free)?

Gemini 3 Flash Preview costs $0.5/M input tokens and Grok 4 Fast (free) costs $0/M input tokens. Grok 4 Fast (free) is $0.50/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Gemini 3 Flash Preview and Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of Gemini 3 Flash Preview and Grok 4 Fast (free) across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

Updated Dec 2025

Gemini 3 Flash PreviewvsGrok 4 Fast (free)

Grok 4 Fast (free) is cheaper than Gemini 3 Flash Preview at $0/M vs $0.5/M input tokens.

Gemini 3 Flash Preview and Grok 4 Fast (free) compared across 35 shared prompts
Spec	Gemini 3 Flash Preview	Grok 4 Fast (free)
Input price	$0.5/M tokens	Free
Output price	$3/M tokens	Free
Context window	1.0M tokens	2.0M tokens
Weights	Closed	—
Free API (OpenRouter)	No	No
Released	Dec 2025	Sep 2025