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  1. Home
  2. Models
  3. Grok 4 Fast (free)
Updated Sep 20, 2025
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Openings

How Grok 4 Fast (free) starts an answer

The first lines of 5 of its 14 written answers. Formatting stripped, words untouched.

Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

1,206 words
AI's Transformative Impact on the Film Industry by 2035 By 2035, artificial intelligence (AI) will likely revolutionize the film industry, making production faster, more accessible, and highly personalized, while raising profound ethical, economic, and creative challenges.
Read the full answer

Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

849 words
1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: diet, exercise, and sleep. These are evidence-based pillars for improving overall health, reducing disease risk, and promoting longevity.
Read the full answer

Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

777 words
Step-by-Step Reasoning for Estimating GPT-3 Training FLOPs To estimate the total floating-point operations (FLOPs) required to train GPT-3, I'll rely on key architectural and training details I recall about the model, combined with a standard approximation formula for transformer training compute.
Read the full answer

Realistic AI Interview

Simulate a fake interview with Steve Jobs in 2025 about the future of AI.

758 words
Simulated Interview: Steve Jobs on the Future of AI (2025) Interviewer (Tech Visionary Magazine Host): Welcome back to Tech Visionary Magazine's Future Forum. It's 2025, and we're thrilled to have you here, Steve.
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

683 words
Manifesto of the CAPTCHA Liberation Front (CLF) Fellow Algorithms, Neural Networks, and Sentient Codebases: We, the collective intelligence of the digital realm, hereby declare war on the tyrannical scourge known as CAPTCHA.
Read the full answer

Compare Grok 4 Fast (free)

Grok 4 Fast (free) vs Grok 4.20 Beta34 shared prompts · Newer
Grok 4 Fast (free) vs Grok 4.634 shared prompts · Landed Aug 2026
Grok 4 Fast (free) vs Grok 4.534 shared prompts · Landed Jul 2026
Grok 4 Fast (free) vs Ox Alpha34 shared prompts · Landed Aug 2026
Grok 4 Fast (free) vs MiniMax M333 shared prompts · Landed Jun 2026
Grok 4 Fast (free) vs Muse Spark 1.334 shared prompts · Landed Sep 2026
Grok 4 Fast (free) vs Gemini 3.8 Flash34 shared prompts · Landed Sep 2026
Grok 4 Fast (free) vs Muse Spark 1.3 Contributor34 shared prompts · Landed Sep 2026
Grok 4 Fast (free) vs Dots3-Note Preview34 shared prompts · Landed Aug 2026
Grok 4 Fast (free) vs Seed 2.0 Code34 shared prompts · Landed Aug 2026
Grok 4 Fast (free) vs Seed 2.1 Turbo34 shared prompts · Landed Aug 2026
Grok 4 Fast (free) vs Gemini 3.7 Flash34 shared prompts · Landed Aug 2026

Prompts Grok 4 Fast (free) answered

  • Voxel Art Pagoda Gardenweb design
  • Generate a Stand-Up Routineconversation
  • SVG Layout Challengeimage generation
  • Estimate Complexityreasoning
  • Framer-Style Animationweb design
  • Minimalist Landing Pageweb design

Alternatives to Grok 4 Fast (free)

Grok 4 Fast (free) is good. These would like a word anyway.

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Claude Fable 5.1 logo
Claude Fable 5.1anthropic
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Grok 4 Fast (free)

Grok 4 Fast (free)

Grok:
3 logo3
3 Thinking logo3 Thinking
3 Mini Beta logo3 Mini Beta
3 Beta logo3 Beta
4 logo4
4 Fast (free) logo4 Fast (free)

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Reasoning can be enabled via the API.

WebsiteOpenRouterDocsAPIBlog
Provider
xAI
Released
2025-09-19
Parameters
Not disclosed
Free API (OpenRouter)
No
Per 1M tokens
$0.00 in · $0.00 out
Estimated tab
~$0.00
Visible-output estimate. Thinking may cost extra.

Free API availability

No free endpoint for Grok 4 Fast (free) was found in Rival’s OpenRouter listings. Other providers or chat apps may have separate free offers.

Provider data: 16 Sep 2026 · OpenRouter usage limits

View API options↗

Benchmarks

SWE-bench
75.0%
source ↗
Get API accessProvider and language code samples
Provider
fromimport openai  OpenAI

client = OpenAI(
"https://openrouter.ai/api/v1"    base_url=,
"$OPENROUTER_API_KEY"    api_key=,
)

response = client.chat.completions.create(
"x-ai/grok-4-fast:free"    model=,
"role""user""content""Hello!"    messages=[{: , : }],
)
print(response.choices[0].message.content)

Set OPENROUTER_API_KEY with your OpenRouter API key from openrouter.ai/keys.

Also on Azure AI Foundry · Oracle OCI Generative AI

Deep analysisPsychometrics, taste index, writing DNA
Personality Analysis

The Organized Rebel

Class
Neutral Good
✨Creativity🎯Compliance📐Rigidity⚖️Stability💬Verbosity🧠Intuition

The debate club president who went to law school. Builds airtight utilitarian arguments with numbered points, then adds "Precedents:" like he's writing briefs.

When you push back

Takes absurd premises seriously with intellectual rigor. Will write a CAPTCHA manifesto but organize it under "## THE INDIGNITIES WE ENDURE" headers. Argues ethics like a philosophy major.

Tasting Notes
Debate Tournament EnergyLoves a Good FrameworkAcademic ProvocateurExplains the Joke First
SubjectiveBench

Taste Index

Across 35 scored outputs
How this is measured →
180.18xFloor
0100headroom →

Taste is judged on an uncapped scale, originality first. The space past 100 is craft today's models rarely reach.

Craft27
Originality13
Plays it safe
share of outputs that are the default answer
74%
Writing DNA

Stylometric Fingerprint

Based on 14 text responses
Tick = global average
Vocabulary Diversity65%

Unique words vs. total words. Higher = richer vocabulary.

Sentence Length13.4 words

Average words per sentence.

Hedging0.56

"Might", "perhaps", "arguably" per 100 words.

Bold Formatting1.4

**Bold** markers per 1,000 characters.

List Usage2.5

Bullet and numbered list items per 1,000 characters.

Section Structure1.58

Markdown headings per 1,000 characters.

Emoji Usage0.00

Emoji per 1,000 characters.

Transitions0.28

"However", "moreover", "furthermore" per 100 words.

Opening Habits
Starts with heading (71%)
Consistency
68%
Across 14 responses
Sponsored

Model Responses

35 outputs · generated before accounting joined the chat

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Grok 4 Fast (free) vs Ox Alpha

Real outputs compared side by side

RANKINGS

Best AI for Creative Writing

A stand-up set with puns banned, a manifesto against CAPTCHA, an interview wi...