What is the difference between Claude Sonnet 5 and xAI: Grok 4 Fast (free)?

Claude Sonnet 5 is developed by Anthropic while xAI: Grok 4 Fast (free) is developed by xAI. Claude Sonnet 5 has a 1.0M token context window vs xAI: Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 5 or xAI: Grok 4 Fast (free)?

It depends on your use case. Claude Sonnet 5 and xAI: Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 34 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 5 cost compared to xAI: Grok 4 Fast (free)?

Claude Sonnet 5 costs $2/M input tokens and xAI: Grok 4 Fast (free) costs $0/M input tokens. xAI: Grok 4 Fast (free) is $2.00/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 Claude Sonnet 5 and xAI: Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of Claude Sonnet 5 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 Claude Sonnet 5 and xAI: Grok 4 Fast (free)?

Claude Sonnet 5 is developed by Anthropic while xAI: Grok 4 Fast (free) is developed by xAI. Claude Sonnet 5 has a 1.0M token context window vs xAI: Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 5 or xAI: Grok 4 Fast (free)?

It depends on your use case. Claude Sonnet 5 and xAI: Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 34 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 5 cost compared to xAI: Grok 4 Fast (free)?

Claude Sonnet 5 costs $2/M input tokens and xAI: Grok 4 Fast (free) costs $0/M input tokens. xAI: Grok 4 Fast (free) is $2.00/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 Claude Sonnet 5 and xAI: Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of Claude Sonnet 5 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.

Claude Sonnet 5 vs xAI: Grok 4 Fast (free): Which Is Better?

Updated Jun 2026

Our Verdict

Claude Sonnet 5

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

Claude Sonnet 5

Input

$2.00

Output

$10.00

xAI: Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Writing DNA

Style Comparison

Similarity

52%

Claude Sonnet 5 uses 79.4x more emoji

Claude Sonnet 5

xAI: Grok 4 Fast (free)

59%Vocabulary65%

35wSentence Length13w

0.53Hedging0.56

3.5Bold1.4

3.5Lists2.5

0.79Emoji0.00

1.25Headings1.58

0.06Transitions0.28

Based on 27 + 14 text responses

Research

What we learned reading every model

Claude Sonnet 5 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

xAI: Grok 4 Fast (free) vs MiniMax M3New provider

xAI: Grok 4 Fast (free) vs Claude Sonnet 4Cross-provider

xAI: Grok 4 Fast (free) vs Pony AlphaNew provider

Updated Jun 2026

Our Verdict

Claude Sonnet 5

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

Claude Sonnet 5

Input

$2.00

Output

$10.00

xAI: Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Writing DNA

Style Comparison

Similarity

52%

Claude Sonnet 5 uses 79.4x more emoji

Claude Sonnet 5

xAI: Grok 4 Fast (free)

59%Vocabulary65%

35wSentence Length13w

0.53Hedging0.56

3.5Bold1.4

3.5Lists2.5

0.79Emoji0.00

1.25Headings1.58

0.06Transitions0.28

Based on 27 + 14 text responses

Research

What we learned reading every model

Claude Sonnet 5 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

xAI: Grok 4 Fast (free) vs MiniMax M3New provider

xAI: Grok 4 Fast (free) vs Claude Sonnet 4Cross-provider

xAI: Grok 4 Fast (free) vs Pony AlphaNew provider