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Seed 2.0 Pro vs Step-3.5-Flash

Seed 2.0 Pro and Step-3.5-Flash are closely matched at 39.5 and 37.1 on the LLM Stats Score. Step-3.5-Flash is 6.4x cheaper per token.

ByteDance · StepFun · Updated for 2026

Which is better?

Seed 2.0 Pro and Step-3.5-Flash are closely matched on the overall LLM Stats Score at 39.5 and 37.1.

In the 4 individual benchmarks reported for both models, Seed 2.0 Pro wins 4; this is a narrower head-to-head signal than the composite indexes.

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.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Seed 2.0 Pro

  • you value its reported benchmark strengths — it wins 4 of 4 exact shared results
  • 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

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

At a glance

The differences that matter most.

Seed 2.0 Pro
ByteDance
Step-3.5-Flash
StepFun
Core performance indexes
LLM Stats Score
39.5
#63
37.1
#76
Reasoning
39.0
#64
37.2
#75
Coding
22.0
#90
20.4
#104
Agents
16.8
#85
15.3
#92
Cost, coverage & limits
Benchmark wins
4 of 4
0 of 4
Input price
$0.50 / M
$0.10 / M
Output price
$3.00 / M
$0.40 / M
Context window
256,000
65,536

Capability indexes

Additional strengths measured across groups of related public benchmarks

1 shared
Index
Seed 2.0 Pro
Step-3.5-Flash
Math
32.2#64
33.9#52
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

6 reported for Seed 2.0 Pro · 7 for Step-3.5-Flash

4 shared

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.

Fri Oct 02 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

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
Fri Oct 02 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?

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 131,072 tokens, while Step-3.5-Flash is limited to 8,192 tokens.

ByteDance
Seed 2.0 Pro
Input256,000 tokens
Output131,072 tokens
StepFun
Step-3.5-Flash
Input65,536 tokens
Output8,192 tokens
Fri Oct 02 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

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

7 months ago

1w newer
Step-3.5-Flash

Feb 2, 2026

8 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?

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

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 and Step-3.5-Flash are closely matched on the LLM Stats Score at 39.5 and 37.1. 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 capability indexes, individual benchmarks, pricing, and limits 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 LLM Stats Score (39.5 vs 37.1), 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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