Superseded by Mythos 5.1 — same model as Fable 5, safeguards lifted, partner-only.
100
Coding
97
Writing
99
Research
87
Images
12
Value
98
Long Context
Published benchmarks
95.5%
SWE-bench
1,932
Arena Elo
94.2%
MMLU
83.5%
GPQA
97.4%
MATH
Use this when
Frontier cybersecurity research, autonomous vulnerability discovery, and the absolute capability ceiling
Skip this if
You don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price.
Pricing
$10.00/1M in
$50.00/1M out
→0%since Jun 2026
Context
1M tokens
Speed
Deliberate
Launched June 9, 2026 alongside Fable 5, following the April Project Glasswing private preview on Google Cloud. Restricted to vetted enterprise and research partners due to advanced cybersecurity capabilities. Same underlying model and benchmarks as Claude Fable 5. Superseded by Claude Mythos 5.1 on September 1, 2026.
80.3% SWE-Bench Pro — tied with Fable 5 as the highest public coding score of any model
Safeguards lifted in some areas for advanced security and research workloads
Excels at complex, multi-step cybersecurity tasks under partner access
Same 1M-token context and 1932 GDPval-AA score as Fable 5
Weaknesses
Not generally available — limited to vetted partners after Project Glasswing's private preview
Most teams should use Fable 5, which is the same model with standard safeguards
Premium $10/$50 pricing and a deliberate, high-latency profile
Real-world use cases
What people actually use Claude Mythos 5 for.
Multi-step cybersecurity workflows: vulnerability discovery, exploit reasoning, and containment analysis
High-stakes autonomous engineering where the safety-tuned Fable 5 is too constrained
Frontier research programs running under Anthropic's vetted-partner access controls
How Claude Mythos 5 compares
The nearest models people weigh against it, and what actually separates them.
vs Claude Fable 5.1 — Against Claude Fable 5.1 (Anthropic), Claude Mythos 5 lands within a few percent on price. Which one wins depends on whether context depth or latency is your constraint.
vs Claude Mythos 5.1 — Against Claude Mythos 5.1 (Anthropic), Claude Mythos 5 lands within a few percent on price. Which one wins depends on whether context depth or latency is your constraint.
vs Claude Fable 5 — Against Claude Fable 5 (Anthropic), Claude Mythos 5 lands within a few percent on price. Which one wins depends on whether context depth or latency is your constraint.
Price History
Claude Mythos 5 pricing over time
→0% since Jun 11
78 data points · tracked daily since Jun 11, 2026
Ready to try it?
Start using Claude Mythos 5
Frontier cybersecurity research, autonomous vulnerability discovery, and the absolute capability ceiling. Start free — no card required.
Anthropic's September 1, 2026 frontier release and the new capability ceiling for coding, agents, and scientific work. Base pricing is unchanged at $10/$50, but cache reads dropped 75% to $0.25/1M — roughly 25% cheaper on typical workloads and up to 45% cheaper on agentic ones. 1M context, 128K output, adaptive thinking always on.
Verdict
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Released September 1, 2026 alongside Claude Mythos 5.1, the first update to the Mythos-class line since Fable 5 on June 9. API ID claude-fable-5-1; generally available on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry. Published launch numbers (Fable 5.1 / Fable 5 / Opus 5 / GPT-5.6 Sol): Terminal-Bench-Science 0.1 52.6 / 24.7 / 29.0 / 22.4; Terminal-Bench 4.0 55.8 / 42.0 / 52.3 / 37.3; CursorBench 3.2.0 73.4 / 70.5 / 70.0 / 67.2; AutomationBench 31.4 / 17.1 / 26.9 / 19.6; OSWorld 2.0 strict 41.7 / 36.1 / 39.6; Humanity's Last Exam (no tools) 60.9 / 57.8 / 56.6; GDPval-AA v2 1853 / 1723 / 1824 / 1711. GDPval-AA v2 is rescaled from the v1 numbers quoted on the Fable 5 page and is not directly comparable to them.
The unrestricted twin of Claude Fable 5.1 — the same model with safeguards lifted in high-risk areas, released September 1, 2026 to vetted cybersecurity and life-sciences organisations under Anthropic's trusted-access programme. Scores 60.9% on Terminal-Bench 4.0, the highest agentic-coding result Anthropic has published.
Verdict
Fable 5.1 with the safeguards lifted — partner-only, 60.9% Terminal-Bench 4.0.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Released September 1, 2026 alongside Claude Fable 5.1, continuing the Mythos-class line that began with Project Glasswing's April 2026 private preview. Access is limited to vetted US cybersecurity and life-sciences professionals. Same underlying model, pricing, context window, and cache-read discount as Fable 5.1; the only published difference is the safeguard level and the resulting Terminal-Bench 4.0 score (60.9% vs 55.8%).
Anthropic's new Mythos-class flagship and the most capable coding model anyone can use — 80.3% SWE-Bench Pro, an 11-point jump over Opus 4.8. 1M context, 128K output, native parallel subagents. Released June 9, 2026.
Verdict
Superseded by Fable 5.1 — still 80.3% SWE-Bench Pro, but 5.1 is better and cheaper to run.
Quality score
98%
Pricing
$10.00/1M in
$50.00/1M out
Speed
Deliberate
2/5 speed
Context
1M tokens
Launched June 9, 2026 as the public, Mythos-class release. Available on the Claude API, Microsoft Foundry, and Google Vertex AI. Free for all users until June 22, 2026. Same underlying model as Claude Mythos 5, with safeguards that block specific high-risk cyber responses. Superseded by Claude Fable 5.1 on September 1, 2026 — same $10/$50 base pricing, cache reads cut from $1.00 to $0.25 per 1M tokens.
SWE-Bench Pro 80.3%Mythos-classParallel subagentsAgenticLong contextPremiumSuperseded
Best for
The hardest coding tasks, autonomous multi-step agents, and frontier-grade reasoning
Claude Mythos 5 costs $10 per million input tokens and $50 per million output tokens on the API. A month of 10M input and 2M output tokens runs about $200.00 at list price, before any batch or caching discounts.
What is Claude Mythos 5 best for?
Claude Mythos 5 is best for frontier cybersecurity research, autonomous vulnerability discovery, and the absolute capability ceiling. It is a strong fit when that workflow matters more than the tradeoffs around premium pricing and deliberate speed.
When should I avoid Claude Mythos 5?
You don't have vetted-partner access or don't need lifted safeguards — Fable 5 is the same model, generally available, at the same price.
What is a cheaper alternative to Claude Mythos 5?
Grok 4.5 (xAI) at $2.00/1M/1M input against Claude Mythos 5's $10.00/1M/1M — roughly 87% less per token all in. Best cost-per-solved-task coding agent — efficiency over ceiling. Compare it first if Claude Mythos 5's pricing is the thing stopping you.
What is a faster alternative to Claude Mythos 5?
Claude Fable 5.1 — deliberate against Claude Mythos 5's deliberate, with 1M tokens of context. Worth the swap when response time is what your users notice rather than the last few points of reasoning depth.
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