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Grok-4 Fast Reasoning vs Muse Spark Open

Comparing Grok-4 Fast Reasoning and Muse Spark Open across benchmarks, pricing, and capabilities.

xAI · Meta · Updated for 2026

Which is better?

Grok-4 Fast Reasoning and Muse Spark Open trade strengths across price, capabilities, and technical limits. The better choice depends on the workload.

On price, Grok-4 Fast Reasoning is roughly 7.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Grok-4 Fast Reasoning also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Grok-4 Fast Reasoning

  • cost matters — it's about 7.3x cheaper per token
  • you process long inputs — it offers a 2,000,000 token context window

Choose Muse Spark Open

  • you want the most recent training data — it shipped Oct 2026
  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

Grok-4 Fast Reasoning
xAI
Muse Spark Open
Meta
Benchmark wins
—
—
Input price
$0.20 / M
$1.25 / M
Output price
$0.50 / M
$4.25 / M
Context window
2,000,000
1,048,576

Individual benchmarks

0 reported for Grok-4 Fast Reasoning · 17 for Muse Spark Open

No common benchmarks found

Grok-4 Fast Reasoning and Muse Spark Opendon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Grok-4 Fast Reasoning costs less

For input processing, Grok-4 Fast Reasoning ($0.20/1M tokens) is 6.3x cheaper than Muse Spark Open ($1.25/1M tokens).

For output processing, Grok-4 Fast Reasoning ($0.50/1M tokens) is 8.5x cheaper than Muse Spark Open ($4.25/1M tokens).

In conclusion, Muse Spark Open is more expensive than Grok-4 Fast Reasoning.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Mon Oct 19 2026 • llm-stats.com
xAI
Grok-4 Fast Reasoning
Input tokens$0.20
Output tokens$0.50
Best providerxAI
Meta
Muse Spark Open
Input tokens$1.25
Output tokens$4.25
Best providerTogether
Notice missing or incorrect data?

Context Window

Maximum input and output token capacity

Grok-4 Fast Reasoning accepts 2,000,000 input tokens compared to Muse Spark Open's 1,048,576 tokens. Muse Spark Open can generate longer responses up to 1,048,576 tokens, while Grok-4 Fast Reasoning is limited to 30,000 tokens.

xAI
Grok-4 Fast Reasoning
Input2,000,000 tokens
Output30,000 tokens
Meta
Muse Spark Open
Input1,048,576 tokens
Output1,048,576 tokens
Mon Oct 19 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Grok-4 Fast Reasoning and Muse Spark Open support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Grok-4 Fast Reasoning

Text
Images
Audio
Video

Muse Spark Open

Text
Images
Audio
Video

License

Usage and distribution terms

Grok-4 Fast Reasoning is licensed under a proprietary license, while Muse Spark Open uses Muse Model License.

License differences may affect how you can use these models in commercial or open-source projects.

Grok-4 Fast Reasoning

Proprietary

Closed source

Muse Spark Open

Muse Model License

Open weights

Release Timeline

When each model was launched

Grok-4 Fast Reasoning was released on 2025-08-28, while Muse Spark Open was released on 2026-10-15.

Muse Spark Open is 14 months newer than Grok-4 Fast Reasoning.

Grok-4 Fast Reasoning

Aug 28, 2025

1.1 years ago

Muse Spark Open

Oct 15, 2026

2 days ago

1.1yr newer

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Provider Availability

Grok-4 Fast Reasoning is available from xAI. Muse Spark Open is available from Together.

Grok-4 Fast Reasoning

xai logo
xAI
Input Price:Input: $0.20/1MOutput Price:Output: $0.50/1M

Muse Spark Open

together logo
Together
Input Price:Input: $1.25/1MOutput Price:Output: $4.25/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Grok-4 Fast Reasoning and Muse Spark Open side-by-side, then vote on the output you prefer.

Grok-4 Fast Reasoning
✓ Preferred
Muse Spark Open
Open in Playground

FAQ

Common questions about Grok-4 Fast Reasoning vs Muse Spark Open.

Which is better, Grok-4 Fast Reasoning or Muse Spark Open?

Grok-4 Fast Reasoning (xAI) and Muse Spark Open (Meta) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does Grok-4 Fast Reasoning compare to Muse Spark Open in benchmarks?

Muse Spark Open scores MCP Atlas: 89.2%, GPQA: 89.0%, OSWorld-Verified: 80.4%, BabyVision: 80.2%, Terminal-Bench 2.1: 76.4%.

Is Grok-4 Fast Reasoning cheaper than Muse Spark Open?

Grok-4 Fast Reasoning is 6.3x cheaper for input tokens. Grok-4 Fast Reasoning costs $0.20/M input and $0.50/M output via xai. Muse Spark Open costs $1.25/M input and $4.25/M output via together.

What are the context window sizes for Grok-4 Fast Reasoning and Muse Spark Open?

Grok-4 Fast Reasoning supports 2.0M tokens and Muse Spark Open supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Grok-4 Fast Reasoning and Muse Spark Open?

Key differences include context window (2.0M vs 1.0M), input pricing ($0.20 vs $1.25/M), licensing (Proprietary vs Muse Model License). See the full comparison above for benchmark-by-benchmark results.

Who makes Grok-4 Fast Reasoning and Muse Spark Open?

Grok-4 Fast Reasoning is developed by xAI and Muse Spark Open is developed by Meta.

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