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Comparison · 2 models · Updated Oct 4, 2026

DeepSeek-V3.1 vs Qwen3.5 Plus

Qwen3.5 Plus comes out ahead, 66 to 55 on our weighted score, though DeepSeek-V3.1 is 33% cheaper per token.

  1. DeepSeek

    DeepSeek-V3.1

    Released Aug 21, 2025

    55/100
    • ECI139.9
    • Price$0.385 / $1.25
    • Context131K
    Full specs Remove DeepSeek-V3.1
  2. Our pick

    Alibaba (Qwen)

    Qwen3.5 Plus

    Released Feb 16, 2026

    66/100
    • ECI146.8
    • Price$0.40 / $2.40
    • Context1M
    Full specs Remove Qwen3.5 Plus

  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Qwen3.5 Plus is our pick

Qwen3.5 Plus is the better all-round choice, scoring 66/100 against DeepSeek-V3.1 (55). It leads on capability, inputs & features and context window. DeepSeek-V3.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityQwen3.5 PlusCapabilities Index (ECI): Qwen3.5 Plus 146.8 · DeepSeek-V3.1 139.9
  • Lowest priceDeepSeek-V3.1DeepSeek-V3.1 $0.601 · Qwen3.5 Plus $0.90 per 1M tokens (3:1 blend)
  • Longest contextQwen3.5 PlusQwen3.5 Plus 1,000,000 · DeepSeek-V3.1 131,072 tokens
  • Widest inputsQwen3.5 PlusDeepSeek-V3.1: Text · Qwen3.5 Plus: Text, Images, Video
  • Self-hostingDeepSeek-V3.1Publishes downloadable weights (MIT License)
How the score is built
MeasureWeightDeepSeek-V3.1Qwen3.5 Plus
CapabilityCapabilities Index (ECI)50%6574
Price25%6052
Inputs & features15%3570
Context window10%2460
Overall100%55/10066/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

DeepSeek-V3.1 vs Qwen3.5 Plus specifications side by side
SpecificationDeepSeek-V3.1DeepSeekQwen3.5 PlusAlibaba (Qwen)
Capability
Capabilities Index (ECI)139.9146.8 (best)
ECI rank#100 of 148#65 of 148 (best)
GPQA DiamondGraduate-level science questions—84.9%
OTIS Mock AIME 2024–2025Competition mathematics—86.7%
SimpleQA VerifiedShort factual questions—25.4%
Price per million tokens
Input$0.385 (best)$0.40
Output$1.25 (best)$2.40
Cached input——
Blended (3:1)$0.601 (best)$0.90
Long-context rateSame rateSame rate
Price sourceMedian of 8 providersOfficial Alibaba API
Limits
Context window131,072 tokens1,000,000 tokens (best)
Max output8,192 tokens65,536 tokens (best)
Inputs and features
TextYesYes
ImagesNoYes
PDFsNoNo
AudioNoNo
VideoNoYes
ReasoningYesYes
Tool callingYesYes
Structured outputNoNo
Availability
WeightsOpenMIT LicenseProprietary
API model ID—qwen3.5-plus
API providers810 (best)
ReleasedAug 21, 2025Feb 16, 2026
Knowledge cutoff—Apr 2025
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • DeepSeek-V3.1$6.35
  • Qwen3.5 Plus$8.80
04 — Questions

Which should you choose?

Which is better: DeepSeek-V3.1 or Qwen3.5 Plus?

Qwen3.5 Plus is the better all-round choice, scoring 66/100 against DeepSeek-V3.1 (55). It leads on capability, inputs & features and context window. DeepSeek-V3.1 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, DeepSeek-V3.1 or Qwen3.5 Plus?

DeepSeek-V3.1 is cheaper at $0.385 input / $1.25 output per million tokens (median across 8 API providers). Qwen3.5 Plus costs $0.40 input / $2.40 output per million tokens (official Alibaba API price). At a typical mix of three input tokens to one output token, that is $0.601 per million tokens for DeepSeek-V3.1 versus $0.90 for Qwen3.5 Plus (1.5× as much).

Which scores higher on benchmarks?

Qwen3.5 Plus scores higher on the Capabilities Index (ECI): Qwen3.5 Plus 146.8 (#65 of 148) and DeepSeek-V3.1 139.9 (#100 of 148). Their confidence ranges do not overlap (144.6–148.1 vs 136.1–143.3), so the gap is a real one.

Which is better for coding?

There are no published SWE-bench Verified results for DeepSeek-V3.1 and Qwen3.5 Plus yet, so there is no like-for-like coding score. On overall capability, Qwen3.5 Plus leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

Qwen3.5 Plus has the largest context window at 1,000,000 tokens, against 131,072 for DeepSeek-V3.1. Maximum output per response: DeepSeek-V3.1 up to 8,192, Qwen3.5 Plus up to 65,536 tokens.

Which can read images, PDFs, audio or video?

DeepSeek-V3.1 accepts text; Qwen3.5 Plus accepts text, images and video. Qwen3.5 Plus handles the widest range of inputs.

Are any of these open source?

DeepSeek-V3.1 publishes its weights (MIT License) and can be self-hosted; Qwen3.5 Plus is proprietary.

Which is newer?

Qwen3.5 Plus is the newest, released Feb 16, 2026. DeepSeek-V3.1 came out Aug 21, 2025. Knowledge cutoff: Qwen3.5 Plus Apr 2025.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.

05 — Keep comparing

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