Grok-4 Heavy vs Muse Spark Open
Grok-4 Heavy and Muse Spark Open are closely matched at 40.7 and 44.9 on the LLM Stats Score.
xAI · Meta · Updated for 2026
Which is better?
Grok-4 Heavy and Muse Spark Open are closely matched on the overall LLM Stats Score at 40.7 and 44.9.
In the 1 individual benchmarks reported for both models, Muse Spark Open wins 1; this is a narrower head-to-head signal than the composite indexes.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Grok-4 Heavy
- you are already invested in the xAI ecosystem
Choose Muse Spark Open
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- you need open weights you can self-host or fine-tune
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
6 reported for Grok-4 Heavy · 17 for Muse Spark Open
Grok-4 Heavy outperforms in 0 benchmarks, while Muse Spark Open is better at 1 benchmark (GPQA).
Muse Spark Open significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Context Window
Maximum input and output token capacity
Only Muse Spark Open specifies input context (1,048,576 tokens). Only Muse Spark Open specifies output context (1,048,576 tokens).
Input capabilities
Documented input modalities across available providers
Both Grok-4 Heavy and Muse Spark Open support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Grok-4 Heavy
Muse Spark Open
License
Usage and distribution terms
Grok-4 Heavy 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.
Proprietary
Closed source
Muse Model License
Open weights
Release Timeline
When each model was launched
Muse Spark Open was released on 2026-10-15, while Grok-4 Heavy's release date is not specified.
We can confirm Muse Spark Open's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.
—
Oct 15, 2026
4 days ago
Knowledge Cutoff
When training data ends
Grok-4 Heavy has a documented knowledge cutoff of 2024-12-31, while Muse Spark Open's cutoff date is not specified.
We can confirm Grok-4 Heavy's training data extends to 2024-12-31, but cannot make a direct comparison without Muse Spark Open's cutoff date.
Dec 2024
—
Outputs Comparison
Judge for yourself.
Run your own prompts against Grok-4 Heavy and Muse Spark Open side-by-side, then vote on the output you prefer.
FAQ
Common questions about Grok-4 Heavy vs Muse Spark Open.