Model Comparison

Seed 2.0 Pro vs Step-3.5-FlashWhich is better in 2026?

Seed 2.0 Pro significantly outperforms across most benchmarks. Step-3.5-Flash is 6.4x cheaper per token.

Verdict: Seed 2.0 Pro vs Step-3.5-Flash — which is better?

Seed 2.0 Pro (by ByteDance) and Step-3.5-Flash (by StepFun) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.

Seed 2.0 Pro outperforms in 4 benchmarks (AIME 2025, BrowseComp, LiveCodeBench v6, SWE-Bench Verified), while Step-3.5-Flash is better at 0 benchmarks. Seed 2.0 Pro significantly outperforms across most benchmarks.

On price, Step-3.5-Flash is roughly 6.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Seed 2.0 Pro also accepts a larger context window (256,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose Seed 2.0 Pro if…

  • you want the strongest raw capability — it leads on 4 of 4 shared benchmarks
  • you process long inputs — it offers a 256,000 token context window
  • you want the most recent training data — it shipped Feb 2026

Choose Step-3.5-Flash if…

  • cost matters — it's about 6.4x cheaper per token
  • you need open weights you can self-host or fine-tune

Performance Benchmarks

Comparative analysis across standard metrics

4 benchmarks

Seed 2.0 Pro outperforms in 4 benchmarks (AIME 2025, BrowseComp, LiveCodeBench v6, SWE-Bench Verified), while Step-3.5-Flash is better at 0 benchmarks.

Seed 2.0 Pro significantly outperforms across most benchmarks.

Sun Jul 26 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Step-3.5-Flash costs less

For input processing, Seed 2.0 Pro ($0.50/1M tokens) is 5.0x more expensive than Step-3.5-Flash ($0.10/1M tokens).

For output processing, Seed 2.0 Pro ($3.00/1M tokens) is 7.5x more expensive than Step-3.5-Flash ($0.40/1M tokens).

In conclusion, Seed 2.0 Pro is more expensive than Step-3.5-Flash.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Sun Jul 26 2026 • llm-stats.com
ByteDance
Seed 2.0 Pro
Input tokens$0.50
Output tokens$3.00
Best providerDeepinfra
StepFun
Step-3.5-Flash
Input tokens$0.10
Output tokens$0.40
Best providerStepFun
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Seed 2.0 Pro accepts 256,000 input tokens compared to Step-3.5-Flash's 65,536 tokens. Seed 2.0 Pro can generate longer responses up to 65,536 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

ByteDance
Seed 2.0 Pro
Input256,000 tokens
Output65,536 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Sun Jul 26 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Seed 2.0 Pro supports multimodal inputs, whereas Step-3.5-Flash does not.

Seed 2.0 Pro can handle both text and other forms of data like images, making it suitable for multimodal applications.

Seed 2.0 Pro

Text
Images
Audio
Video

Step-3.5-Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Seed 2.0 Pro is licensed under a proprietary license, while Step-3.5-Flash uses Apache 2.0.

License differences may affect how you can use these models in commercial or open-source projects.

Seed 2.0 Pro

Proprietary

Closed source

Step-3.5-Flash

Apache 2.0

Open weights

Release Timeline

When each model was launched

Seed 2.0 Pro was released on 2026-02-14, while Step-3.5-Flash was released on 2026-02-02.

Seed 2.0 Pro is 0 month newer than Step-3.5-Flash.

Seed 2.0 Pro

Feb 14, 2026

5 months ago

1w newer
Step-3.5-Flash

Feb 2, 2026

5 months ago

Knowledge Cutoff

When training data ends

Seed 2.0 Pro has a documented knowledge cutoff of 2024-01-01, while Step-3.5-Flash's cutoff date is not specified.

We can confirm Seed 2.0 Pro's training data extends to 2024-01-01, but cannot make a direct comparison without Step-3.5-Flash's cutoff date.

Seed 2.0 Pro

Jan 2024

Step-3.5-Flash

—

Provider Availability

Seed 2.0 Pro is available from DeepInfra. Step-3.5-Flash is available from StepFun.

Seed 2.0 Pro

deepinfra logo
Deepinfra
Input Price:Input: $0.50/1MOutput Price:Output: $3.00/1M

Step-3.5-Flash

stepfun logo
StepFun
Input Price:Input: $0.10/1MOutput Price:Output: $0.40/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

ByteDance
Larger context window (256,000 tokens)
Supports multimodal inputs
Higher AIME 2025 score (98.3% vs 97.3%)
Higher BrowseComp score (77.3% vs 69.0%)
Higher LiveCodeBench v6 score (87.8% vs 86.4%)
Higher SWE-Bench Verified score (76.5% vs 74.4%)
StepFun
Less expensive input tokens
Less expensive output tokens
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Seed 2.0 Pro and Step-3.5-Flash side-by-side, then vote on the output you prefer.

Seed 2.0 Pro
✓ Preferred
Step-3.5-Flash
Open in Playground
AI Model Comparison Table
Feature
ByteDance
Seed 2.0 Pro
StepFun
Step-3.5-Flash

FAQ

Common questions about Seed 2.0 Pro vs Step-3.5-Flash.

Which is better, Seed 2.0 Pro or Step-3.5-Flash?

Seed 2.0 Pro significantly outperforms across most benchmarks. Seed 2.0 Pro is made by ByteDance and Step-3.5-Flash is made by StepFun. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Seed 2.0 Pro compare to Step-3.5-Flash in benchmarks?

Seed 2.0 Pro scores AIME 2025: 98.3%, AIME 2026: 94.2%, GPQA: 88.9%, LiveCodeBench v6: 87.8%, BrowseComp: 77.3%. Step-3.5-Flash scores AIME 2025: 97.3%, Tau-bench: 88.2%, LiveCodeBench v6: 86.4%, IMO-AnswerBench: 85.4%, SWE-Bench Verified: 74.4%.

Is Seed 2.0 Pro cheaper than Step-3.5-Flash?

Step-3.5-Flash is 5.0x cheaper for input tokens. Seed 2.0 Pro costs $0.50/M input and $3.00/M output via deepinfra. Step-3.5-Flash costs $0.10/M input and $0.40/M output via stepfun.

What are the context window sizes for Seed 2.0 Pro and Step-3.5-Flash?

Seed 2.0 Pro supports 256K tokens and Step-3.5-Flash supports 66K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Seed 2.0 Pro and Step-3.5-Flash?

Key differences include context window (256K vs 66K), input pricing ($0.50 vs $0.10/M), multimodal support (yes vs no), licensing (Proprietary vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.

Who makes Seed 2.0 Pro and Step-3.5-Flash?

Seed 2.0 Pro is developed by ByteDance and Step-3.5-Flash is developed by StepFun.

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