GPT-5.1vsMuse Spark 1.3
Muse Spark 1.3 has a larger context window than GPT-5.1 (1.0M tokens vs 400K tokens).
| Spec | GPT-5.1 | Muse Spark 1.3 |
|---|---|---|
| Input price | $1.25/M tokens | $1.25/M tokens |
| Output price | $10/M tokens | $4.25/M tokens |
| Context window | 400K tokens | 1.0M tokens |
| Weights | Closed | Closed |
| Free API (OpenRouter) | No | No |
| Released | Nov 2025 | Sep 2026 |
Our Verdict
GPT-5.1
Muse Spark 1.3
Not enough votes to call it. On the specs, nothing separates them.
Too close to call
Reviewing agent-written code?See a Brief PR report
API pricing
Cost per 1M tokens
GPT-5.1
Input
$1.25
Output
$10.00
Muse Spark 1.3
Input
$1.25
Output
$4.25
2.4× cheaper
Where to run it
3 hosts
Muse Spark 1.31 host
Per million tokens. Prices and uptime via OpenRouter, checked 11 Sep 2026.
Writing DNA
Style Comparison
Similarity
51%
GPT-5.1 uses 3.2x more lists
GPT-5.1
Muse Spark 1.3
62%Vocabulary59%
19wSentence Length14w
0.29Hedging0.28
3.5Bold2.6
7.2Lists2.3
0.00Emoji0.00
0.61Headings0.48
0.03Transitions0.02
Based on 14 + 27 text responses
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