Claude Mythos 5.1 vs Muse Spark Open
Claude Mythos 5.1 and Muse Spark Open are closely matched at 44.3 and 45.3 on the LLM Stats Score. Muse Spark Open is 10.0x cheaper per token.
Anthropic · Meta · Updated for 2026
Which is better?
Claude Mythos 5.1 and Muse Spark Open are closely matched on the overall LLM Stats Score at 44.3 and 45.3.
On price, Muse Spark Open is roughly 10.0x 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 Claude Mythos 5.1
- you want predictable pricing at $10.00/M input and $50.00/M output
Choose Muse Spark Open
- cost matters — it's about 10.0x cheaper per token
- you process long inputs — it offers a 1,048,576 token context window
- 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.
Individual benchmarks
1 reported for Claude Mythos 5.1 · 17 for Muse Spark Open
Claude Mythos 5.1 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
For input processing, Claude Mythos 5.1 ($10.00/1M tokens) is 8.0x more expensive than Muse Spark Open ($1.25/1M tokens).
For output processing, Claude Mythos 5.1 ($50.00/1M tokens) is 11.8x more expensive than Muse Spark Open ($4.25/1M tokens).
In conclusion, Claude Mythos 5.1 is more expensive than Muse Spark Open.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Muse Spark Open accepts 1,048,576 input tokens compared to Claude Mythos 5.1's 1,000,000 tokens. Muse Spark Open can generate longer responses up to 1,048,576 tokens, while Claude Mythos 5.1 is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Mythos 5.1 and Muse Spark Open support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Mythos 5.1
Muse Spark Open
License
Usage and distribution terms
Claude Mythos 5.1 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
Claude Mythos 5.1 was released on 2026-09-01, while Muse Spark Open was released on 2026-10-15.
Muse Spark Open is 1 month newer than Claude Mythos 5.1.
Sep 1, 2026
1 months ago
Oct 15, 2026
1 weeks ago
1mo newerKnowledge Cutoff
When training data ends
Neither model specifies a knowledge cutoff date.
Unable to compare the recency of their training data.
Provider Availability
Claude Mythos 5.1 is available from Anthropic. Muse Spark Open is available from Together.
Claude Mythos 5.1
Muse Spark Open
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Mythos 5.1 and Muse Spark Open side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Mythos 5.1 vs Muse Spark Open.