GPT-5.4 Pro
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:$19.5/M. Automatic prefix caching once a prompt passes the minimum length, with no code changes; cached reads are discounted (up to 90% on current models) and there is no write fee.
Use GPT-5.4 Pro 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="gpt-5.4-pro",
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: "gpt-5.4-pro",
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": "gpt-5.4-pro",
"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: "gpt-5.4-pro",
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("gpt-5.4-pro")
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));About GPT-5.4 Pro
GPT-5.4 Pro is the premium reasoning tier of the GPT-5.4 family: per OpenAI, it "uses more compute to think harder and provide consistently better answers," producing smarter, more precise responses on tough problems.
- It keeps the 1,050,000-token context window (vendor spec) and 128K max output, accepts image input, and supports reasoning effort at medium, high, and xhigh; long-running requests may take several minutes, so background execution is recommended.
- Synthorai makes GPT-5.4 Pro callable through its OpenAI-compatible interface right alongside the standard models.
Specs & limits
| Max output (vendor spec) | 128,000 |
| Modalities | text + image → text |
| Features | tools · streaming · vision · batch · reasoning · computer_use |
| Notable | Higher-compute pro tier; structured outputs not supported; multi-turn use is Responses-API-only; requests may take minutes (background mode recommended); 1.05M context. |
| Prompt caching | automatic · min 1,024-token prefix · TTL 5–10m, up to 1h |
FAQ
Is the GPT-5.4 Pro API free to try?
Yes: new accounts get 10 trial calls and up to $1 in free credit, no card required. At $30/M input tokens, that credit alone covers roughly 4 requests of ~8K tokens against GPT-5.4 Pro.
What is GPT-5.4 Pro best at?
Uses more compute to think harder, plus consistently better answers on tough problems and background execution for multi-minute requests. See the About section for the full picture from the vendor's own release notes.
How much does GPT-5.4 Pro cost?
GPT-5.4 Pro costs $30 per million input tokens and $180 per million output tokens on Synthorai. That is the provider's list price, with no platform markup. Cached input tokens bill at $15/M.
Does GPT-5.4 Pro support prompt caching?
Yes, automatically: OpenAI-served prompts cache with no code changes. Cached input tokens bill at $15/M vs $30/M uncached; prompts need a 1,024-token stable prefix to cache (TTL 5–10m, up to 1h). Prompt caching guide →
How do I get access to GPT-5.4 Pro?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="gpt-5.4-pro", and you're done. One API key covers every model on the gateway.
What is GPT-5.4 Pro's knowledge cutoff?
GPT-5.4 Pro's knowledge cutoff is 2025-08, per the vendor's official documentation (as of 2026-07-09).