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Comparison · 2 models · Updated Oct 4, 2026

Seed 2.1 Pro vs GPT-5.6 Cyber

Seed 2.1 Pro comes out ahead, 50 to 30 on our weighted score, and it is the cheaper option too.

  1. Our pick

    ByteDance Seed

    Seed 2.1 Pro

    Released Jun 23, 2026

    50/100
    • ECI—
    • Price$0.891 / $4.45
    • Context256K
  2. OpenAI

    GPT-5.6 Cyber

    Released Aug 7, 2026

    30/100
    • ECI—
    • Price$12.50 / $75.00
    • Context400K
  3. Add a model

    Make it a three-way comparison.

01 — Verdict

Seed 2.1 Pro is our pick

Seed 2.1 Pro is the better all-round choice, scoring 50/100 against GPT-5.6 Cyber (30). It leads on price and inputs & features. GPT-5.6 Cyber wins on context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

  • CapabilityNot enough dataNo independent benchmark covers every model here yet
  • Lowest priceSeed 2.1 ProSeed 2.1 Pro $1.78 · GPT-5.6 Cyber $28.13 per 1M tokens (3:1 blend)
  • Longest contextGPT-5.6 CyberGPT-5.6 Cyber 400,000 · Seed 2.1 Pro 256,000 tokens
  • Widest inputsSeed 2.1 ProSeed 2.1 Pro: Text, Images, Video · GPT-5.6 Cyber: Text, Images
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightSeed 2.1 ProGPT-5.6 Cyber
Price50%380
Inputs & features30%8070
Context window20%3644
Overall100%50/10030/100

Left out because at least one model lacks the data: capability. The remaining weights were rescaled.

02 — Side by side

Every spec in one table

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

Seed 2.1 Pro vs GPT-5.6 Cyber specifications side by side
SpecificationSeed 2.1 ProByteDance SeedGPT-5.6 CyberOpenAI
Capability
Capabilities Index (ECI)——
ECI rank——
Price per million tokens
Input$0.891 (best)$12.50
Output$4.45 (best)$75.00
Cached input$0.178 (best)$1.25
Blended (3:1)$1.78 (best)$28.13
Long-context rateSame rateSame rate
Price sourceOfficial Volcengine Ark APIOfficial OpenAI API
Limits
Context window256,000 tokens400,000 tokens (best)
Max output256,000 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoNo
AudioNoNo
VideoYesNo
ReasoningYesminimal · low · medium · high · xhigh · maxYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDdoubao-seed-2-1-pro-260628gpt-daybreak-red-latest
API providers2 (best)1
ReleasedJun 23, 2026Aug 7, 2026
Knowledge cutoff—Feb 16, 2026
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.

  • Seed 2.1 Pro$17.81
  • GPT-5.6 Cyber$275.00
04 — Questions

Which should you choose?

Which is better: Seed 2.1 Pro or GPT-5.6 Cyber?

Seed 2.1 Pro is the better all-round choice, scoring 50/100 against GPT-5.6 Cyber (30). It leads on price and inputs & features. GPT-5.6 Cyber wins on context window. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.

Which is cheaper, Seed 2.1 Pro or GPT-5.6 Cyber?

Seed 2.1 Pro is cheaper at $0.891 input / $4.45 output per million tokens (official Volcengine Ark API price). GPT-5.6 Cyber costs $12.50 input / $75.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $1.78 per million tokens for Seed 2.1 Pro versus $28.13 for GPT-5.6 Cyber (16× as much).

Which scores higher on benchmarks?

There is no independent benchmark that covers both models yet. Seed 2.1 Pro has not been scored yet and GPT-5.6 Cyber has not been scored yet.

Which is better for coding?

There are no published SWE-bench Verified results for Seed 2.1 Pro and GPT-5.6 Cyber yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. Both support tool calling for agent workflows.

Which has the bigger context window?

GPT-5.6 Cyber has the largest context window at 400,000 tokens, against 256,000 for Seed 2.1 Pro. Maximum output per response: Seed 2.1 Pro up to 256,000, GPT-5.6 Cyber up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Seed 2.1 Pro accepts text, images and video; GPT-5.6 Cyber accepts text and images. Seed 2.1 Pro handles the widest range of inputs.

Are any of these open source?

No. Seed 2.1 Pro and GPT-5.6 Cyber are proprietary and only available through APIs and apps.

Which is newer?

GPT-5.6 Cyber is the newest, released Aug 7, 2026. Seed 2.1 Pro came out Jun 23, 2026. Knowledge cutoff: GPT-5.6 Cyber Feb 16, 2026.

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.