What is the difference between Grok 4 Fast (free) and Mercury?

Grok 4 Fast (free) is developed by xAI while Mercury is developed by Inception. Grok 4 Fast (free) has a 2.0M token context window vs Mercury's 32K. You can compare their actual outputs across 35 challenges on Rival to see how they differ in practice.

Which is better, Grok 4 Fast (free) or Mercury?

It depends on your use case. Grok 4 Fast (free) and Mercury 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 Grok 4 Fast (free) cost compared to Mercury?

Grok 4 Fast (free) costs $0/M input tokens and Mercury costs $10/M input tokens. Grok 4 Fast (free) is $10.00/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 Grok 4 Fast (free) and Mercury on Rival?

This page shows a side-by-side comparison of Grok 4 Fast (free) and Mercury 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 Grok 4 Fast (free) and Mercury?

Grok 4 Fast (free) is developed by xAI while Mercury is developed by Inception. Grok 4 Fast (free) has a 2.0M token context window vs Mercury's 32K. You can compare their actual outputs across 35 challenges on Rival to see how they differ in practice.

Which is better, Grok 4 Fast (free) or Mercury?

It depends on your use case. Grok 4 Fast (free) and Mercury 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 Grok 4 Fast (free) cost compared to Mercury?

Grok 4 Fast (free) costs $0/M input tokens and Mercury costs $10/M input tokens. Grok 4 Fast (free) is $10.00/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 Grok 4 Fast (free) and Mercury on Rival?

This page shows a side-by-side comparison of Grok 4 Fast (free) and Mercury 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.

Grok 4 Fast (free) vs Mercury: Which Is Better?

Updated Sep 2025

Our Verdict

Grok 4 Fast (free)

MercuryRunner-up

No community votes yet. On paper, Grok 4 Fast (free) has the edge — bigger model tier, newer, bigger context window, major provider backing.

Slight edge

What do Grok 4 Fast (free) and Mercury say about your brand?

10 models, one question, verbatim receipts.

or peek at a demo: Notion Linear Vercel

API pricing

Cost per 1M tokens

Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Mercury

Input

$10.00

Output

$10.00

Writing DNA

Style Comparison

Similarity

37%

Mercury uses 4.3x more emoji

Grok 4 Fast (free)

Mercury

65%Vocabulary55%

13wSentence Length40w

0.56Hedging0.39

1.4Bold4.9

2.5Lists3.8

0.00Emoji0.04

1.58Headings1.04

0.28Transitions0.03

Based on 14 + 17 text responses

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Mercury vs MiniMax M3New provider

Mercury vs Ox AlphaNew provider

Mercury vs Claude Sonnet 4New provider

Updated Sep 2025

Our Verdict

Grok 4 Fast (free)

MercuryRunner-up

No community votes yet. On paper, Grok 4 Fast (free) has the edge — bigger model tier, newer, bigger context window, major provider backing.

Slight edge

What do Grok 4 Fast (free) and Mercury say about your brand?

10 models, one question, verbatim receipts.

or peek at a demo: Notion Linear Vercel

API pricing

Cost per 1M tokens

Grok 4 Fast (free)

Input

$0.000

Output

$0.000

Mercury

Input

$10.00

Output

$10.00

Writing DNA

Style Comparison

Similarity

37%

Mercury uses 4.3x more emoji

Grok 4 Fast (free)

Mercury

65%Vocabulary55%

13wSentence Length40w

0.56Hedging0.39

1.4Bold4.9

2.5Lists3.8

0.00Emoji0.04

1.58Headings1.04

0.28Transitions0.03

Based on 14 + 17 text responses

Research

What we learned reading every model

FAQ

Common questions

Keep exploring

More comparisons

Mercury vs MiniMax M3New provider

Mercury vs Ox AlphaNew provider

Mercury vs Claude Sonnet 4New provider