DeepSeek V4 Flash vs GLM-5.1
DeepSeek V4 Flash (2026) and GLM-5.1 (2026) are frontier-tier reasoning models from DeepSeek and Zhipu AI. DeepSeek V4 Flash ships a 1M-token context window, while GLM-5.1 ships a 200K-token context window. On SWE-bench Pro, GLM-5.1 leads by 5.8 pts. On pricing, DeepSeek V4 Flash ranges from $0.22 to $0.44/1M input tokens by tier; GLM-5.1 costs $1.38/1M input tokens. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
DeepSeek V4 Flash fits 5x more tokens; pick it for long-context work and GLM-5.1 for tighter calls.
Decision scorecard
Local evidence first| Signal | DeepSeek V4 Flash | GLM-5.1 |
|---|---|---|
| Best for | reasoning-heavy apps, tool-calling agents, and long-context analysis | reasoning-heavy apps, tool-calling agents, and provider-routed production |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1M | 200K |
| Cheapest output | $0.12/1M tokens | $4.40/1M tokens |
| Provider routes | 5 tracked | 5 tracked |
| Shared benchmarks | 7 shared | SWE-bench Pro leader |
Decision tradeoffs
- DeepSeek V4 Flash holds a shared-benchmark lead on Google-Proof Q&A, ahead by 1.9 points.
- DeepSeek V4 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- DeepSeek V4 Flash has the lower cheapest tracked output price at $0.12/1M tokens.
- Local decision data tags DeepSeek V4 Flash for Coding, RAG, and Agents.
- GLM-5.1 holds a shared-benchmark lead on SWE-bench Pro, ahead by 5.8 points.
- GLM-5.1 uniquely exposes Code execution in local model data.
- Local decision data tags GLM-5.1 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
DeepSeek V4 Flash
$76.26
Cheapest tracked route/tier: OpenRouter
GLM-5.1
$2,204
Cheapest tracked route/tier: Novita AI
Estimated monthly gap: $2,128. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter, Vercel AI Gateway, and Novita AI; start route-level A/B tests there.
- GLM-5.1 is $4.28/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GLM-5.1 adds Code execution in local capability data.
- Provider overlap exists on OpenRouter, Vercel AI Gateway, and Novita AI; start route-level A/B tests there.
- DeepSeek V4 Flash is $4.28/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Code execution before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-24 | 2026-04-07 |
| Context window | 1M | 200K |
| Parameters | 284B | 754B total, 40B active |
| Architecture | Mixture of Experts | Mixture of Experts |
| License | MITOSI-approved | MITOSI-approved |
| Openness | Open source | Open source |
| Weights | Available | Available |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: permitted | Commercial use: permitted |
| Knowledge cutoff | - | 2025-11 |
Pricing and availability
| Pricing attribute | DeepSeek V4 Flash | GLM-5.1 |
|---|---|---|
| Input price |
| $1.38/1M tokens |
| Output price |
| $4.40/1M tokens |
| Providers |
Capabilities
| Capability | DeepSeek V4 Flash | GLM-5.1 |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | DeepSeek V4 Flash | GLM-5.1 |
|---|---|---|
| SWE-bench Pro | 52.6 | 58.4 |
| Google-Proof Q&A | 88.1 | 86.2 |
| Humanity's Last Exam | 34.8 | 31.0 |
| Chatbot Arena | 1437.0 | 1475.0 |
| Terminal-Bench 2.0 | 56.9 | 63.5 |
| MCP-Atlas | 69.0 | 71.8 |
| GeneBench-Pro | 2.4 | 1.2 |
Deep dive
On shared benchmark coverage, SWE-bench Pro has DeepSeek V4 Flash at 52.6 and GLM-5.1 at 58.4, with GLM-5.1 ahead by 5.8 points; Google-Proof Q&A has DeepSeek V4 Flash at 88.1 and GLM-5.1 at 86.2, with DeepSeek V4 Flash ahead by 1.9 points; Humanity's Last Exam has DeepSeek V4 Flash at 34.8 and GLM-5.1 at 31, with DeepSeek V4 Flash ahead by 3.8 points. The largest visible gap is 5.8 points on SWE-bench Pro, 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 code execution: GLM-5.1. Both models share reasoning mode, JSON / 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, DeepSeek V4 Flash lists tiered pricing: Off-peak is $0.22/1M input and $0.66/1M output; Peak is $0.44/1M input and $1.32/1M output, while GLM-5.1 lists $1.38/1M input and $4.40/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts DeepSeek V4 Flash lower by about $2.21 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 5 providers versus 5, so concentration risk also matters.
Choose DeepSeek V4 Flash when long-context analysis, larger context windows, and lower cheapest-tier input-token cost are central to the workload. Choose GLM-5.1 when coding workflow support 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, DeepSeek V4 Flash or GLM-5.1?
DeepSeek V4 Flash supports 1M tokens, while GLM-5.1 supports 200K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, DeepSeek V4 Flash or GLM-5.1?
DeepSeek V4 Flash lists tiered pricing: Off-peak is $0.22/1M input and $0.66/1M output; Peak is $0.44/1M input and $1.32/1M output. GLM-5.1 lists $1.38/1M input and $4.40/1M output tokens on the cheapest tracked provider. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is DeepSeek V4 Flash or GLM-5.1 open source?
DeepSeek V4 Flash is listed under MIT. GLM-5.1 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 reasoning mode, DeepSeek V4 Flash or GLM-5.1?
Both DeepSeek V4 Flash and GLM-5.1 expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for JSON / Tool use, DeepSeek V4 Flash or GLM-5.1?
Both DeepSeek V4 Flash and GLM-5.1 expose JSON / Tool use. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run DeepSeek V4 Flash and GLM-5.1?
DeepSeek V4 Flash is available on DeepSeek Platform, OpenRouter, Microsoft Foundry, Vercel AI Gateway, and Novita AI. GLM-5.1 is available on Z.ai, OpenRouter, Fireworks AI, Vercel AI Gateway, and Novita AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-10-08. Data sourced from public model cards and provider documentation.