# Seed 1.8

> Seed 1.8 is a proprietary language model from ByteDance Seed, released on 1 Sept 2025. It accepts text and images and generates text, with a 256K-token context window and up to 33K output tokens per response. As of 4 Oct 2026, the lowest listed API price is $0.25 per million input tokens and $2 per million output tokens (Vercel AI Gateway), across 1 provider we track.

Source page: https://www.aimodel.directory/models/seed-1-8
Last verified: 4 Oct 2026

## Specifications

- **Developer:** ByteDance Seed
- **Release date:** 1 Sept 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Weights:** Proprietary (API only) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Context window:** 256K (256,000 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Max output:** 33K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Knowledge cutoff:** Oct 2024 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Input:** Text and images (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Reasoning mode:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)
- **Tool calling:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/vercel/models/bytedance/seed-1.8.toml)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|
| Vercel AI Gateway | $0.25 | $2 | $0.05 | 256K |

## FAQ

### What is the context window of Seed 1.8?

Seed 1.8 has a context window of 256,000 tokens (256K) and can generate up to 32,768 tokens in a single response, according to models.dev.

### How much does the Seed 1.8 API cost?

Seed 1.8 is listed from $0.25 per million input tokens and $2 per million output tokens (Vercel AI Gateway). Prices last verified 4 Oct 2026.

### Is Seed 1.8 open source?

No. Seed 1.8 is a proprietary model; ByteDance Seed has not released its weights. It is available through APIs including Vercel AI Gateway.

### When was Seed 1.8 released?

ByteDance Seed released Seed 1.8 on 1 Sept 2025, according to models.dev.

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Data licensed CC BY 4.0. Cite as: AI Model Directory, "Seed 1.8", https://www.aimodel.directory/models/seed-1-8