Decision support
Claude Mythos 5.1 vs Viv Fast
Compare canonical objects directly. The useful dimensions change with the object type, so model and hardware comparisons stay separate.
Benchmark results
No benchmark results have been matched to these models yet.
Model specifications
Release date
September 1, 2026
September 21, 2026
Context window
1M
1M
Native context
—
—
Max output tokens
128,000
256,000
Knowledge cutoff
2026-06
2026-09
Open weights
Closed
Closed
Parameter count
—
—
API pricing · USD per 1M tokens
Input
—
—
Output
—
—
Cached input
—
—
Cache write
—
—
Capabilities and modalities
Input modalities
text, image, file
text, image
Output modalities
text
text
Tool calling
Supported
Supported
Reasoning option
Supported
Supported
Supported options
tools, reasoning
tools, structured_outputs, reasoning
Capabilities
—
—
Architecture and availability
Architecture
—
—
Model families
—
—
Tokenizer
—
—
Instruction format
—
—
License
—
—
Providers
0
0
Provider endpoints
0
0
Ollama variants
0
0
Metadata source
models.dev
ai-research
A dash means the field is not reported. Provider-specific performance and pricing may differ.