Hy4 preview vs LongCat-2.5-Preview vs Seed Evolving
Too close to call on our weighted score (LongCat-2.5-Preview 52, Seed Evolving 50, Hy4 preview 45). The right pick depends on what you value most.
TencentHy4 preview
45/100- ECI—
- Price$0.834 / $2.50
- Context1.02M
Meituan (LongCat)LongCat-2.5-Preview
52/100- ECI—
- Price$0.75 / $2.95
- Context1M
ByteDance SeedSeed Evolving
50/100- ECI—
- Price$0.891 / $4.45
- Context256K
Too close to call
It is close. Our weighted score puts them within 2 points (LongCat-2.5-Preview 52/100, Seed Evolving 50/100, Hy4 preview 45/100), so choose by what matters most for your work: Hy4 preview on price and Hy4 preview for long inputs. 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 priceHy4 previewHy4 preview $1.25 · LongCat-2.5-Preview $1.30 · Seed Evolving $1.78 per 1M tokens (3:1 blend)
- Longest contextHy4 previewHy4 preview 1,024,000 · LongCat-2.5-Preview 1,000,000 · Seed Evolving 256,000 tokens
- Widest inputsSeed EvolvingHy4 preview: Text · LongCat-2.5-Preview: Text, Images · Seed Evolving: Text, Images, Video
- Self-hostingHy4 previewPublishes downloadable weights
| Measure | Weight | Hy4 preview | LongCat-2.5-Preview | Seed Evolving |
|---|---|---|---|---|
| Price | 50% | 45 | 44 | 38 |
| Inputs & features | 30% | 35 | 60 | 80 |
| Context window | 20% | 60 | 60 | 36 |
| Overall | 100% | 45/100 | 52/100 | 50/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Hy4 previewTencent | LongCat-2.5-PreviewMeituan (LongCat) | Seed EvolvingByteDance Seed |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | — | — |
| ECI rank | — | — | — |
| Price per million tokens | |||
| Input | $0.834 | $0.75 (best) | $0.891 |
| Output | $2.50 (best) | $2.95 | $4.45 |
| Cached input | $0.042 (best) | — | $0.178 |
| Blended (3:1) | $1.25 (best) | $1.30 | $1.78 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Tencent TokenHub API | Median of 1 providers | Official Volcengine Ark API |
| Limits | |||
| Context window | 1,024,000 tokens (best) | 1,000,000 tokens | 256,000 tokens |
| Max output | 64,000 tokens | 131,072 tokens | 256,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | No | Yes | Yes |
| PDFs | No | No | No |
| Audio | No | No | No |
| Video | No | No | Yes |
| Reasoning | Yeshigh | Yes | Yesminimal · low · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | No | No | Yes |
| Availability | |||
| Weights | Open | Proprietary | Proprietary |
| API model ID | hy4-preview | — | doubao-seed-evolving |
| API providers | 13 (best) | 2 | 2 |
| Released | Aug 28, 2026 | Sep 25, 2026 | Jun 23, 2026 |
| Knowledge cutoff | — | — | — |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Hy4 preview$13.34
- LongCat-2.5-Preview$13.40
- Seed Evolving$17.81
Which should you choose?
Which is better: Hy4 preview, LongCat-2.5-Preview or Seed Evolving?
It is close. Our weighted score puts them within 2 points (LongCat-2.5-Preview 52/100, Seed Evolving 50/100, Hy4 preview 45/100), so choose by what matters most for your work: Hy4 preview on price and Hy4 preview for long inputs. 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, Hy4 preview, LongCat-2.5-Preview or Seed Evolving?
Hy4 preview is cheaper at $0.834 input / $2.50 output per million tokens (official Tencent TokenHub API price). LongCat-2.5-Preview costs $0.75 input / $2.95 output per million tokens (median across 1 API provider); Seed Evolving costs $0.891 input / $4.45 output per million tokens (official Volcengine Ark API price). At a typical mix of three input tokens to one output token, that is $1.25 per million tokens for Hy4 preview versus $1.30 for LongCat-2.5-Preview (1× as much) and $1.78 for Seed Evolving (1.4× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. Hy4 preview has not been scored yet, LongCat-2.5-Preview has not been scored yet and Seed Evolving has not been scored yet.
Which is better for coding?
There are no published SWE-bench Verified results for Hy4 preview, LongCat-2.5-Preview and Seed Evolving yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
Hy4 preview has the largest context window at 1,024,000 tokens, against 1,000,000 for LongCat-2.5-Preview and 256,000 for Seed Evolving. Maximum output per response: Hy4 preview up to 64,000, LongCat-2.5-Preview up to 131,072, Seed Evolving up to 256,000 tokens.
Which can read images, PDFs, audio or video?
Hy4 preview accepts text; LongCat-2.5-Preview accepts text and images; Seed Evolving accepts text, images and video. Seed Evolving handles the widest range of inputs.
Are any of these open source?
Hy4 preview publishes its weights and can be self-hosted; LongCat-2.5-Preview and Seed Evolving is proprietary.
Which is newer?
LongCat-2.5-Preview is the newest, released Sep 25, 2026. Hy4 preview came out Aug 28, 2026; Seed Evolving came out Jun 23, 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.
