Claude Sonnet 5
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:$0.74/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 Sonnet 5 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-sonnet-5",
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-sonnet-5",
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-sonnet-5",
"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-sonnet-5",
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-sonnet-5")
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));About Claude Sonnet 5
Claude Sonnet 5 is the next generation of Anthropic's Sonnet family ("the best combination of speed and intelligence"), positioned as a drop-in capability upgrade over Sonnet 4.6, with the largest gains in coding and agentic tasks.
- It ships a 1M-token context window by default, 128K max output, adaptive thinking on by default with effort-level control, a new tokenizer, vision input, and the full Claude tool set; introductory pricing applies through August 31, 2026.
- On Synthorai, Claude Sonnet 5 answers on the same OpenAI-compatible API as every other catalog model.
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 | Introductory pricing $2/$10 per MTok through 2026-08-31; 1M context; adaptive thinking on by default; new tokenizer (~30% more tokens); non-default sampling params return 400; no Priority Tier. |
| 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 Sonnet 5 API free to try?
Yes: new accounts get 10 trial calls and up to $1 in free credit, no card required. At $2/M input tokens, that credit alone covers roughly 62 requests of ~8K tokens against Claude Sonnet 5.
What is Claude Sonnet 5 best at?
Largest gains in coding and agentic tasks, plus 1M-token context window by default and drop-in capability upgrade from Sonnet 4.6. See the About section for the full picture from the vendor's own release notes.
How much does Claude Sonnet 5 cost?
Claude Sonnet 5 costs $2 per million input tokens and $10 per million output tokens on Synthorai. That is the provider's list price, with no platform markup. Cached input tokens bill at $0.2/M.
Does Claude Sonnet 5 support prompt caching?
Yes, via opt-in: mark stable prefixes with cache_control breakpoints. Cached input tokens bill at $0.2/M vs $2/M uncached; prompts need a 1,024-token stable prefix to cache (TTL 5m default, 1h option). Prompt caching guide →
How do I get access to Claude Sonnet 5?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="claude-sonnet-5", and you're done. One API key covers every model on the gateway.
What is Claude Sonnet 5's knowledge cutoff?
Claude Sonnet 5's knowledge cutoff is 2026-01, per the vendor's official documentation (as of 2026-07-09).