LLM Reference

DeepSeek V4 Flash vs Gemini 3.5 Flash

DeepSeek V4 Flash (2026) and Gemini 3.5 Flash (2026) are frontier-tier reasoning models from DeepSeek and Google DeepMind. DeepSeek V4 Flash ships a 1m-token context window, while Gemini 3.5 Flash ships a 1.05m-token context window. On SWE-bench Verified, DeepSeek V4 Flash leads by 1 pts. 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 is ~1567% cheaper at $0.09/1M; pay for Gemini 3.5 Flash only for coding workflow support.

Decision scorecard

Local evidence first
SignalDeepSeek V4 FlashGemini 3.5 Flash
Best forreasoning-heavy apps, tool-calling agents, and long-context analysisreasoning-heavy apps, multimodal apps, and tool-calling agents
Decision fitCoding, RAG, and AgentsCoding, RAG, and Agents
Context window1m1.05m
Cheapest output$0.18/1M tokens$9/1M tokens
Provider routes5 tracked4 tracked
Shared benchmarksSWE-bench Verified leader8 shared

Decision tradeoffs

Choose DeepSeek V4 Flash when...
  • DeepSeek V4 Flash holds a shared-benchmark lead on SWE-bench Verified, ahead by 1 points.
  • DeepSeek V4 Flash has the lower cheapest tracked output price at $0.18/1M 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.
Choose Gemini 3.5 Flash when...
  • Gemini 3.5 Flash holds a shared-benchmark lead on SWE-bench Pro, ahead by 2.5 points.
  • Gemini 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
  • Gemini 3.5 Flash uniquely exposes Vision, Multimodal, and Code execution in local model data.
  • Local decision data tags Gemini 3.5 Flash 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.

Lower estimate DeepSeek V4 Flash

DeepSeek V4 Flash

$117

Cheapest tracked route/tier: OpenRouter

Gemini 3.5 Flash

$3,450

Cheapest tracked route/tier: Google AI Studio

Estimated monthly gap: $3,333. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

DeepSeek V4 Flash -> Gemini 3.5 Flash
  • Provider overlap exists on Vercel AI Gateway and OpenRouter; start route-level A/B tests there.
  • Gemini 3.5 Flash is $8.82/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Gemini 3.5 Flash adds Vision, Multimodal, and Code execution in local capability data.
Gemini 3.5 Flash -> DeepSeek V4 Flash
  • Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
  • DeepSeek V4 Flash is $8.82/1M 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.

Specs

Specification
Released2026-04-242026-05-19
Context window1m1.05m
Parameters284B—
ArchitectureMixture of ExpertsDecoder Only
LicenseMITOSI-approvedProprietary
OpennessOpen sourceProprietary
WeightsAvailableNot released
CodeUnknownUnknown
Commercial useCommercial use: permittedCommercial use: conditional
Knowledge cutoff-2025-01

Pricing and availability

Pricing attributeDeepSeek V4 FlashGemini 3.5 Flash
Input price$0.09/1M tokens$1.50/1M tokens
Output price$0.18/1M tokens$9/1M tokens
Providers
DeepSeek PlatformOpenRouterMicrosoft FoundryVercel AI GatewayNovita AI
Google AI StudioGCP Vertex AIVercel AI GatewayOpenRouter

Capabilities

CapabilityDeepSeek V4 FlashGemini 3.5 Flash
VisionNoYes
MultimodalNoYes
ReasoningYesYes
Function callingYesYes
Tool useYesYes
Structured outputsYesYes
Code executionNoYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkDeepSeek V4 FlashGemini 3.5 Flash
SWE-bench Verified79.078.0
SWE-bench Pro52.655.1
Google-Proof Q&A88.192.2
Humanity's Last Exam34.840.2
HumanEval69.592.0
Terminal-Bench 2.056.976.2
MCP-Atlas69.083.6
GeneBench-Pro2.48.1

Deep dive

On shared benchmark coverage, SWE-bench Verified has DeepSeek V4 Flash at 79 and Gemini 3.5 Flash at 78, with DeepSeek V4 Flash ahead by 1 points; SWE-bench Pro has DeepSeek V4 Flash at 52.6 and Gemini 3.5 Flash at 55.1, with Gemini 3.5 Flash ahead by 2.5 points; Google-Proof Q&A has DeepSeek V4 Flash at 88.1 and Gemini 3.5 Flash at 92.2, with Gemini 3.5 Flash ahead by 4.1 points. The largest visible gap is 4.1 points on Google-Proof Q&A, 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: Gemini 3.5 Flash, multimodal input: Gemini 3.5 Flash, and code execution: Gemini 3.5 Flash. 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, DeepSeek V4 Flash lists $0.09/1M input and $0.18/1M output tokens on the cheapest tracked provider, while Gemini 3.5 Flash lists $1.50/1M input and $9/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts DeepSeek V4 Flash lower by about $3.63 per million blended tokens. Availability is 5 providers versus 4, so concentration risk also matters.

Choose DeepSeek V4 Flash when provider fit, lower input-token cost, and broader provider choice are central to the workload. Choose Gemini 3.5 Flash when coding workflow support and larger context windows 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 Gemini 3.5 Flash?

Gemini 3.5 Flash supports 1.05m 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, DeepSeek V4 Flash or Gemini 3.5 Flash?

DeepSeek V4 Flash is cheaper on tracked token pricing. DeepSeek V4 Flash costs $0.09/1M input and $0.18/1M output tokens. Gemini 3.5 Flash costs $1.50/1M input and $9/1M output tokens. Provider discounts or batch pricing can still change the final bill.

Is DeepSeek V4 Flash or Gemini 3.5 Flash open source?

DeepSeek V4 Flash is listed under MIT. Gemini 3.5 Flash is listed under Proprietary. 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, DeepSeek V4 Flash or Gemini 3.5 Flash?

Gemini 3.5 Flash 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, DeepSeek V4 Flash or Gemini 3.5 Flash?

Gemini 3.5 Flash 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 DeepSeek V4 Flash and Gemini 3.5 Flash?

DeepSeek V4 Flash is available on DeepSeek Platform, OpenRouter, Microsoft Foundry, Vercel AI Gateway, and Novita AI. Gemini 3.5 Flash is available on Google AI Studio, GCP Vertex AI, Vercel AI Gateway, and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.

Continue comparing

Model pages
Labs and families
Related comparisons

Popular comparisons for DeepSeek V4 Flash

Popular comparisons for Gemini 3.5 Flash

Last reviewed: 2026-07-03. Data sourced from public model cards and provider documentation.