Claude Opus 4.8
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:$1.85/M. Explicit cache_control breakpoints; cached reads bill at 0.1x the input price, cache writes carry a 1.25x (5-minute TTL) or 2x (1-hour TTL) surcharge; per-model minimum prefix sizes apply.
Use Claude Opus 4.8 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="claude-opus-4-8",
messages=[{"role": "user", "content": "Summarize this diff"}],
reasoning_effort="medium",
)
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: "claude-opus-4-8",
messages: [{ role: "user", content: "Summarize this diff" }],
reasoning_effort: "medium",
});
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": "claude-opus-4-8",
"messages": [{"role": "user", "content": "Hello"}],
"reasoning_effort": "medium"
}'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: "claude-opus-4-8",
Messages: []openai.ChatCompletionMessageParamUnion{
openai.UserMessage("Summarize this diff"),
},
ReasoningEffort: openai.ReasoningEffortMedium,
})
fmt.Println(resp.Choices[0].Message.Content)
}import com.openai.client.OpenAIClient;
import com.openai.client.okhttp.OpenAIOkHttpClient;
import com.openai.models.chat.completions.*;
import com.openai.models.ReasoningEffort;
OpenAIClient client = OpenAIOkHttpClient.builder()
.baseUrl("https://synthorai.io/v1")
.apiKey("sk-syn-...")
.build();
ChatCompletion resp = client.chat().completions().create(
ChatCompletionCreateParams.builder()
.model("claude-opus-4-8")
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));About Claude Opus 4.8
Claude Opus 4.8 is Anthropic's recommended model for complex agentic coding and enterprise work, building directly on Opus 4.7.
- The official what's-new page highlights better long-horizon agentic coding with improved compaction recovery, more reliable reasoning-effort calibration, and fewer skipped tool calls.
- New at launch: mid-conversation system messages that preserve prompt-cache hits, a lower 1,024-token cache minimum (down from 2,048), and a fast-mode research preview with up to 2.5x higher output speed.
- It carries a 1M-token context window, 128K output, adaptive thinking, and vision.
- Synthorai offers it through the OpenAI-compatible endpoint developers already use.
Specs & limits
| Max output (vendor spec) | 128,000 |
| Modalities | text + image → text |
| Features | tools · parallel_tool_calls · structured_output · streaming · vision · batch · caching · reasoning · computer_use |
| Notable | 1M context by default; effort defaults to high; fast mode available as research preview; mid-conversation system messages; min cacheable prompt lowered to 1,024 tokens; high-res image input. |
| Prompt caching | explicit (opt-in) · min 1,024-token prefix · TTL 5m default, 1h option · writes 1.25x (5m) / 2x (1h) |
FAQ
Is the Claude Opus 4.8 API free to try?
Yes: new accounts get 10 trial calls and up to $1 in free credit, no card required. At $5/M input tokens, that credit alone covers roughly 24 requests of ~8K tokens against Claude Opus 4.8.
What is Claude Opus 4.8 best at?
Better long-horizon coding with compaction recovery, plus mid-conversation system messages preserve cache hits and fast-mode preview with 2.5x output speed. See the About section for the full picture from the vendor's own release notes.
How much does Claude Opus 4.8 cost?
Claude Opus 4.8 costs $5 per million input tokens and $25 per million output tokens on Synthorai. That is the provider's list price, with no platform markup. Cached input tokens bill at $0.5/M.
Does Claude Opus 4.8 support prompt caching?
Yes, via opt-in: mark stable prefixes with cache_control breakpoints. Cached input tokens bill at $0.5/M vs $5/M uncached; prompts need a 1,024-token stable prefix to cache (TTL 5m default, 1h option). Claude Opus 4.8 caching guide →
How do I get access to Claude Opus 4.8?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="claude-opus-4-8", and you're done. One API key covers every model on the gateway.
What is Claude Opus 4.8's knowledge cutoff?
Claude Opus 4.8's knowledge cutoff is 2026-01, per the vendor's official documentation (as of 2026-07-09).