ByteDance Seed 1.8
Provider list prices: no platform markup, pay-as-you-go. These are official list prices. Logged-in customers may see effective prices including workspace discounts on /console/pricing. Effective input at a 70% cache-hit rate:$0.11/M. Implicit prefix caching is on by default for Seed language models (1,024-token minimum, no storage fee); an explicit context-caching API is also available. Media models (image / ASR) are not cacheable.
Use ByteDance Seed 1.8 in 30 seconds
OpenAI-compatible: swap the base_url, keep your SDK. POST /v1/chat/completions
from openai import OpenAI
client = OpenAI(
base_url="https://synthorai.io/v1",
api_key="sk-syn-...",
)
resp = client.chat.completions.create(
model="ByteDance-Seed-1.8",
messages=[{"role": "user", "content": "Summarize this diff"}],
)
print(resp.choices[0].message.content)import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://synthorai.io/v1",
apiKey: "sk-syn-...",
});
const resp = await client.chat.completions.create({
model: "ByteDance-Seed-1.8",
messages: [{ role: "user", content: "Summarize this diff" }],
});
console.log(resp.choices[0].message.content);curl https://synthorai.io/v1/chat/completions \
-H "Authorization: Bearer sk-syn-..." \
-H "Content-Type: application/json" \
-d '{
"model": "ByteDance-Seed-1.8",
"messages": [{"role": "user", "content": "Hello"}]
}'package main
import (
"context"
"fmt"
"github.com/openai/openai-go/v3"
"github.com/openai/openai-go/v3/option"
)
func main() {
client := openai.NewClient(
option.WithBaseURL("https://synthorai.io/v1"),
option.WithAPIKey("sk-syn-..."),
)
resp, _ := client.Chat.Completions.New(context.TODO(), openai.ChatCompletionNewParams{
Model: "ByteDance-Seed-1.8",
Messages: []openai.ChatCompletionMessageParamUnion{
openai.UserMessage("Summarize this diff"),
},
})
fmt.Println(resp.Choices[0].Message.Content)
}import com.openai.client.OpenAIClient;
import com.openai.client.okhttp.OpenAIOkHttpClient;
import com.openai.models.chat.completions.*;
OpenAIClient client = OpenAIOkHttpClient.builder()
.baseUrl("https://synthorai.io/v1")
.apiKey("sk-syn-...")
.build();
ChatCompletion resp = client.chat().completions().create(
ChatCompletionCreateParams.builder()
.model("ByteDance-Seed-1.8")
.addUserMessage("Summarize this diff")
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));About ByteDance Seed 1.8
ByteDance-Seed-1.8 is a deep-thinking model on BytePlus ModelArk, currently in beta, that its model page credits with stronger multimodal understanding and agent capabilities and superior performance across a wide range of complex real-world tasks.
- Release notes add upgraded multimodal understanding and more flexible context management.
- It accepts text, image, and video input and returns text, with a 256K context window, 224K maximum input, and 64K output including a 32K chain-of-thought budget, plus function calling, structured output, and context caching.
- Synthorai serves it via its OpenAI-compatible gateway endpoint.
Specs & limits
| Max output (vendor spec) | 65,536 |
| Modalities | text + image + video → text |
| Features | tools · structured_output · streaming · vision · batch · reasoning · caching |
| Notable | Generalized agentic model (search/code/GUI-agent capabilities, native vision); ModelArk id seed-1-8 (version seed-1-8-251228, Beta); 256K context, 64K max output incl. CoT; deep reasoning minimal/low/medium/high; strict-mode function calling. |
| Prompt caching | automatic + explicit · min 1,024-token prefix |
FAQ
Is the ByteDance Seed 1.8 API free to try?
Yes: new accounts get 10 trial calls and up to $1 in free credit, no card required. At $0.25/M input tokens, that credit alone covers roughly 500 requests of ~8K tokens against ByteDance Seed 1.8.
What is ByteDance Seed 1.8 best at?
Stronger multimodal understanding and agent capabilities, plus text, image, and video input and 256K context with 32K chain-of-thought budget. See the About section for the full picture from the vendor's own release notes.
How much does ByteDance Seed 1.8 cost?
ByteDance Seed 1.8 costs $0.25 per million input tokens and $2 per million output tokens on Synthorai. That is the provider's list price, with no platform markup. Cached input tokens bill at $0.05/M.
Does ByteDance Seed 1.8 support prompt caching?
Yes: automatic caching is on by default, with an explicit mode for guaranteed savings. Cached input tokens bill at $0.05/M vs $0.25/M uncached; prompts need a 1,024-token stable prefix to cache. Prompt caching guide →
How do I get access to ByteDance Seed 1.8?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="ByteDance-Seed-1.8", and you're done. One API key covers every model on the gateway.