Seed 1.8
ByteDance
- Released
- December 18, 2025
- Data date
- September 8, 2026
- Successor
- Seed 2.0 Pro
- Price
- Input · Output / 1M tokens
- Input
- Text
- Output
- Text
Seed 1.8 combines three reasoning modes with image understanding and a 256K-token context. ByteDance presents the proprietary service as a generalized agent model for search, coding, and GUI tasks. ByteDance publishes no parameter count, so the accessible model form is defined by its product role and tool surface.
Seed 2.0 Pro is documented as the direct development after it and is positioned by ByteDance as stronger on visual, logical, and unstructured tasks. Seed 1.8 remains a proprietary API service without publicly released weights.
Specifications and access
| Specification | Value and source |
|---|---|
| Weights | ProprietarySource |
| Access | APISource |
| Context window | 256,000 tokensSource |
| Notes | Agentic model with a 256K context window; parameter count is not published.Source |
| Release | 2025-12-18Source |
| License | proprietary BytePlus termsSource |
| API model ID | seed-1-8-251228Source |
| Input | TextSource |
| Output | TextSource |
Measurements without matching peer values
These measurements have no matching peer values under the same test conditions. Their original values and sources remain available here.
BrowseComp-en (Show measurement, test conditions, and source)
- Source value
- 67.6
- Score
- 67.6
- Metric
- percent
- Unit
- %
- Category
- search
- Direction
- Higher is better
- Source type
- vendor-reported
- Evaluator
- ByteDance Seed official benchmark table
- Status
- active
- Retrieved at
- 2026-09-08
- Methodology
- Vendor-reported result. official release prose; exact score stated in text
- Context
- The release page prose states the score; surrounding comparison charts were not used.
VLMsAreBiased (Show measurement, test conditions, and source)
- Source value
- 62
- Score
- 62
- Metric
- percent
- Unit
- %
- Category
- visual-knowledge
- Direction
- Higher is better
- Source type
- vendor-reported
- Evaluator
- ByteDance Seed official benchmark table
- Status
- active
- Retrieved at
- 2026-09-08
- Methodology
- Vendor-reported result. official release prose; exact score stated in text
- Context
- The release page prose states the score; surrounding comparison charts were not used.
VideoMME (Show measurement, test conditions, and source)
- Source value
- 87.8
- Score
- 87.8
- Metric
- percent
- Unit
- %
- Category
- long-video
- Direction
- Higher is better
- Source type
- vendor-reported
- Evaluator
- ByteDance Seed official benchmark table
- Status
- active
- Retrieved at
- 2026-09-08
- Methodology
- Vendor-reported result. official release prose; exact score stated in text
- Context
- The release page prose states the score; surrounding comparison charts were not used.
WorldTravel (Show measurement, test conditions, and source)
- Source value
- 47.2
- Score
- 47.2
- Metric
- percent
- Unit
- %
- Category
- multimodal-agent
- Direction
- Higher is better
- Source type
- vendor-reported
- Evaluator
- ByteDance Seed official benchmark table
- Status
- active
- Retrieved at
- 2026-09-08
- Methodology
- Vendor-reported result. official release prose; exact score stated in text
- Context
- The release page prose states the score; surrounding comparison charts were not used.
ZeroBench (Show measurement, test conditions, and source)
- Source value
- 11
- Score
- 11
- Metric
- percent
- Unit
- %
- Category
- visual-reasoning
- Direction
- Higher is better
- Source type
- vendor-reported
- Evaluator
- ByteDance Seed official benchmark table
- Status
- active
- Retrieved at
- 2026-09-08
- Methodology
- Vendor-reported result. official release prose; exact score stated in text
- Context
- The release page prose states the score; surrounding comparison charts were not used.
Popularity
16.9 / 100
Predecessor and successor
Sources and data date
| Type | Evidence and data date |
|---|---|
| Price | Base API prices without caching or batch discounts. Higher context tiers and other rates are listed under Costs. |
| Input | Documented modalities. Retrieved September 8, 2026. |
| Output | Documented modalities. Retrieved September 8, 2026. |
| Research status | Research date September 8, 2026. 2 source URLs checked. This documents the inspected sources, not an exhaustive inventory of every publication. |
| Not found in the inspected sources | parameters-billions Original wording No exact value located in the checked primary model card/API documentation. |
| Not found in the inspected sources | active-parameters-billions Original wording No exact value located in the checked primary model card/API documentation. |
| Not found in the inspected sources | knowledge-cutoff Original wording No exact value located in the checked primary model card/API documentation. |
| Unresolved | AA benchmark rows Original wording No exact Artificial Analysis model page located in the checked public sitemap. |
| Additional source | Context window data · BytePlus Seed 1.8 documentation · Editorial description reviewed October 2, 2026 |
| Additional source | ByteDance Seed 1.8 release · Editorial description reviewed October 2, 2026 |
| Additional source | ByteDance Seed 2.0 launch · Editorial description reviewed October 2, 2026 |
| Additional source | OpenRouter: Popularity index (derived), CC BY 4.0 |
| Additional source | Vercel AI Gateway: Popularity index (derived), CC BY 4.0 |
| Additional source | Creative Commons Attribution 4.0 |