Claude Mythos Preview vs DeepSeek V4 Flash
Claude Mythos Preview (2026) and DeepSeek V4 Flash (2026) are frontier-tier reasoning models from Anthropic and DeepSeek. Claude Mythos Preview ships a 1M-token context window, while DeepSeek V4 Flash ships a 1M-token context window. On SWE-bench Verified, Claude Mythos Preview leads by 14.9 pts. On pricing, DeepSeek V4 Flash costs $0.14/1M input tokens versus $25/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
DeepSeek V4 Flash is ~17757% cheaper at $0.14/1M; pay for Claude Mythos Preview only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Claude Mythos Preview | DeepSeek V4 Flash |
|---|---|---|
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 1M |
| Cheapest output | $125/1M tokens | $0.28/1M tokens |
| Provider routes | 2 tracked | 3 tracked |
| Shared benchmarks | SWE-bench Verified leader | 2 rows |
Decision tradeoffs
- Claude Mythos Preview leads the largest shared benchmark signal on SWE-bench Verified by 14.9 points.
- Claude Mythos Preview uniquely exposes Vision, Multimodal, and Code execution in local model data.
- Local decision data tags Claude Mythos Preview for Coding, RAG, and Agents.
- DeepSeek V4 Flash has the lower cheapest tracked output price at $0.28/1M tokens.
- DeepSeek V4 Flash has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags DeepSeek V4 Flash for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output prices on this page.
Claude Mythos Preview
$51,250
Cheapest tracked route: Anthropic
DeepSeek V4 Flash
$182
Cheapest tracked route: DeepSeek Platform
Estimated monthly gap: $51,068. Batch, cache, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Microsoft Foundry; start route-level A/B tests there.
- DeepSeek V4 Flash is $125/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Code execution before moving production traffic.
- Provider overlap exists on Microsoft Foundry; start route-level A/B tests there.
- Claude Mythos Preview is $125/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Claude Mythos Preview adds Vision, Multimodal, and Code execution in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-07 | 2026-04-24 |
| Context window | 1M | 1M |
| Parameters | — | 284B |
| Architecture | decoder only | mixture of experts |
| License | Proprietary | MIT |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Pricing attribute | Claude Mythos Preview | DeepSeek V4 Flash |
|---|---|---|
| Input price | $25/1M tokens | $0.14/1M tokens |
| Output price | $125/1M tokens | $0.28/1M tokens |
| Providers |
Capabilities
| Capability | Claude Mythos Preview | DeepSeek V4 Flash |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | No |
Benchmarks
| Benchmark | Claude Mythos Preview | DeepSeek V4 Flash |
|---|---|---|
| SWE-bench Verified | 93.9 | 79.0 |
| Google-Proof Q&A | 94.6 | 88.1 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Mythos Preview at 93.9 and DeepSeek V4 Flash at 79, with Claude Mythos Preview ahead by 14.9 points; Google-Proof Q&A has Claude Mythos Preview at 94.6 and DeepSeek V4 Flash at 88.1, with Claude Mythos Preview ahead by 6.5 points. The largest visible gap is 14.9 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Claude Mythos Preview, multimodal input: Claude Mythos Preview, and code execution: Claude Mythos Preview. Both models share reasoning mode, function calling, tool use, and structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Mythos Preview lists $25/1M input and $125/1M output tokens, while DeepSeek V4 Flash lists $0.14/1M input and $0.28/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts DeepSeek V4 Flash lower by about $54.82 per million blended tokens. Availability is 2 providers versus 3, so concentration risk also matters.
Choose Claude Mythos Preview when coding workflow support are central to the workload. Choose DeepSeek V4 Flash when provider fit, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Mythos Preview or DeepSeek V4 Flash?
Claude Mythos Preview supports 1M tokens, while DeepSeek V4 Flash supports 1M tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Mythos Preview or DeepSeek V4 Flash?
DeepSeek V4 Flash is cheaper on tracked token pricing. Claude Mythos Preview costs $25/1M input and $125/1M output tokens. DeepSeek V4 Flash costs $0.14/1M input and $0.28/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Mythos Preview or DeepSeek V4 Flash open source?
Claude Mythos Preview is listed under Proprietary. DeepSeek V4 Flash is listed under MIT. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Mythos Preview or DeepSeek V4 Flash?
Claude Mythos Preview has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Claude Mythos Preview or DeepSeek V4 Flash?
Claude Mythos Preview has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Claude Mythos Preview and DeepSeek V4 Flash?
Claude Mythos Preview is available on Anthropic and Microsoft Foundry. DeepSeek V4 Flash is available on DeepSeek Platform, OpenRouter, and Microsoft Foundry. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-16. Data sourced from public model cards and provider documentation.