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Muse Spark Open vs Step-3.5-Flash

Muse Spark Open leads the LLM Stats Score 44.9 to 37.0. Step-3.5-Flash is 11.4x cheaper per token.

Meta · StepFun · Updated for 2026

Which is better?

Muse Spark Open leads the overall LLM Stats Score 44.9 to 37.0, ranking #43 overall.

On price, Step-3.5-Flash is roughly 11.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Muse Spark Open also accepts a larger context window (1,048,576 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 Muse Spark Open

  • overall performance matters — it scores 44.9 and ranks #43 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you process long inputs — it offers a 1,048,576 token context window
  • you want the most recent training data — it shipped Oct 2026

Choose Step-3.5-Flash

  • cost matters — it's about 11.4x cheaper per token

At a glance

The differences that matter most.

Muse Spark Open
Meta
Step-3.5-Flash
StepFun
Core performance indexes
LLM Stats Score
44.9
#43
37.0
#86
Reasoning
45.2
#39
37.0
#86
Coding
33.0
#42
20.5
#113
Agents
30.6
#43
15.4
#106
Cost, coverage & limits
Benchmark wins
—
—
Input price
$1.25 / M
$0.10 / M
Output price
$4.25 / M
$0.40 / M
Context window
1,048,576
65,536

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Muse Spark Open
Step-3.5-Flash
Math
31.6#69
33.9#53
Tool use
23.3#44
13.3#115
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

17 reported for Muse Spark Open · 7 for Step-3.5-Flash

No common benchmarks found

Muse Spark Open and Step-3.5-Flashdon'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

Step-3.5-Flash costs less

For input processing, Muse Spark Open ($1.25/1M tokens) is 12.5x more expensive than Step-3.5-Flash ($0.10/1M tokens).

For output processing, Muse Spark Open ($4.25/1M tokens) is 10.6x more expensive than Step-3.5-Flash ($0.40/1M tokens).

In conclusion, Muse Spark Open is more expensive than Step-3.5-Flash.*

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

Lowest available price from all providers
Mon Oct 19 2026 • llm-stats.com
Meta
Muse Spark Open
Input tokens$1.25
Output tokens$4.25
Best providerTogether
StepFun
Step-3.5-Flash
Input tokens$0.10
Output tokens$0.40
Best providerStepFun
Notice missing or incorrect data?

Model Size

Parameter count comparison

620.0B diff

Muse Spark Open has 620.0B more parameters than Step-3.5-Flash, making it 316.3% larger.

Meta
Muse Spark Open
816.0Bparameters
StepFun
Step-3.5-Flash
196.0Bparameters
816.0B
Muse Spark Open
196.0B
Step-3.5-Flash

Context Window

Maximum input and output token capacity

Muse Spark Open accepts 1,048,576 input tokens compared to Step-3.5-Flash's 65,536 tokens. Muse Spark Open can generate longer responses up to 1,048,576 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

Meta
Muse Spark Open
Input1,048,576 tokens
Output1,048,576 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Mon Oct 19 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Muse Spark Open supports multimodal inputs, whereas Step-3.5-Flash does not.

Muse Spark Open can handle both text and other forms of data like images, making it suitable for multimodal applications.

Muse Spark Open

Text
Images
Audio
Video

Step-3.5-Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Muse Spark Open is licensed under Muse Model License, while Step-3.5-Flash uses Apache 2.0.

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

Muse Spark Open

Muse Model License

Open weights

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Muse Spark Open was released on 2026-10-15, while Step-3.5-Flash was released on 2026-02-02.

Muse Spark Open is 9 months newer than Step-3.5-Flash.

Muse Spark Open

Oct 15, 2026

4 days ago

8mo newer
Step-3.5-Flash

Feb 2, 2026

8 months ago

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

Muse Spark Open is available from Together. Step-3.5-Flash is available from StepFun.

Muse Spark Open

together logo
Together
Input Price:Input: $1.25/1MOutput Price:Output: $4.25/1M

Step-3.5-Flash

stepfun logo
StepFun
Input Price:Input: $0.10/1MOutput Price:Output: $0.40/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against Muse Spark Open and Step-3.5-Flash side-by-side, then vote on the output you prefer.

Muse Spark Open
✓ Preferred
Step-3.5-Flash
Open in Playground

FAQ

Common questions about Muse Spark Open vs Step-3.5-Flash.

Which is better, Muse Spark Open or Step-3.5-Flash?

Muse Spark Open leads the LLM Stats Score 44.9 to 37.0. Muse Spark Open is made by Meta and Step-3.5-Flash is made by StepFun. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Muse Spark Open compare to Step-3.5-Flash 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%. Step-3.5-Flash scores AIME 2025: 97.3%, Tau-bench: 88.2%, LiveCodeBench v6: 86.4%, IMO-AnswerBench: 85.4%, SWE-Bench Verified: 74.4%.

Is Muse Spark Open cheaper than Step-3.5-Flash?

Step-3.5-Flash is 12.5x cheaper for input tokens. Muse Spark Open costs $1.25/M input and $4.25/M output via together. Step-3.5-Flash costs $0.10/M input and $0.40/M output via stepfun.

What are the context window sizes for Muse Spark Open and Step-3.5-Flash?

Muse Spark Open supports 1.0M tokens and Step-3.5-Flash supports 66K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Muse Spark Open and Step-3.5-Flash?

Key differences include LLM Stats Score (44.9 vs 37.0), context window (1.0M vs 66K), input pricing ($1.25 vs $0.10/M), multimodal support (yes vs no), licensing (Muse Model License vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.

Who makes Muse Spark Open and Step-3.5-Flash?

Muse Spark Open is developed by Meta and Step-3.5-Flash is developed by StepFun.

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