What is the difference between GPT-4 and xAI: Grok 4 Fast (free)?

GPT-4 is developed by OpenAI while xAI: Grok 4 Fast (free) is developed by xAI. GPT-4 has a 8K token context window vs xAI: Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 10 challenges on Rival to see how they differ in practice.

Which is better, GPT-4 or xAI: Grok 4 Fast (free)?

It depends on your use case. GPT-4 and xAI: Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 10 challenges so you can judge which fits your needs best.

How much does GPT-4 cost compared to xAI: Grok 4 Fast (free)?

GPT-4 costs $30/M input tokens and xAI: Grok 4 Fast (free) costs $0/M input tokens. xAI: Grok 4 Fast (free) is $30.00/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 GPT-4 and xAI: Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of GPT-4 and xAI: 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.

What is the difference between GPT-4 and xAI: Grok 4 Fast (free)?

GPT-4 is developed by OpenAI while xAI: Grok 4 Fast (free) is developed by xAI. GPT-4 has a 8K token context window vs xAI: Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 10 challenges on Rival to see how they differ in practice.

Which is better, GPT-4 or xAI: Grok 4 Fast (free)?

It depends on your use case. GPT-4 and xAI: Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 10 challenges so you can judge which fits your needs best.

How much does GPT-4 cost compared to xAI: Grok 4 Fast (free)?

GPT-4 costs $30/M input tokens and xAI: Grok 4 Fast (free) costs $0/M input tokens. xAI: Grok 4 Fast (free) is $30.00/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 GPT-4 and xAI: Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of GPT-4 and xAI: 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.

GPT-4 vs xAI: Grok 4 Fast (free): Which Is Better?

Updated Sep 2025

Our Verdict

GPT-4

xAI: Grok 4 Fast (free)

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call

API pricing

Cost per 1M tokens

GPT-4

Input

$30.00

Output

$60.00

xAI: Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Writing DNA

Style Comparison

Similarity

55%

xAI: Grok 4 Fast (free) uses 157.7x more headings

GPT-4

xAI: Grok 4 Fast (free)

59%Vocabulary65%

18wSentence Length13w

1.10Hedging0.56

0.8Bold1.4

2.5Lists2.5

0.00Emoji0.00

0.00Headings1.58

0.45Transitions0.28

Based on 15 + 14 text responses

Research

What we learned reading every model

GPT-4 and xAI: Grok 4 Fast (free) have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-4 vs MiniMax M3New provider

xAI: Grok 4 Fast (free) vs Gemini 2.5 Pro Preview 06-05New provider

GPT-4 vs Llama 4 MaverickNew provider

Updated Sep 2025

Our Verdict

GPT-4

xAI: Grok 4 Fast (free)

No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.

Too close to call

API pricing

Cost per 1M tokens

GPT-4

Input

$30.00

Output

$60.00

xAI: Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Writing DNA

Style Comparison

Similarity

55%

xAI: Grok 4 Fast (free) uses 157.7x more headings

GPT-4

xAI: Grok 4 Fast (free)

59%Vocabulary65%

18wSentence Length13w

1.10Hedging0.56

0.8Bold1.4

2.5Lists2.5

0.00Emoji0.00

0.00Headings1.58

0.45Transitions0.28

Based on 15 + 14 text responses

Research

What we learned reading every model

GPT-4 and xAI: Grok 4 Fast (free) have opinions about your brand too.Ask 10 models what they tell people about you. Verbatim receipts.Run the mirror

FAQ

Common questions

Keep exploring

More comparisons

GPT-4 vs MiniMax M3New provider

xAI: Grok 4 Fast (free) vs Gemini 2.5 Pro Preview 06-05New provider

GPT-4 vs Llama 4 MaverickNew provider