Gemini 3.1 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:$0.74/M. Implicit caching is on by default for current Gemini models (discounted automatically on cache hits), plus an explicit CachedContent API with storage-based billing for guaranteed savings.
Use Gemini 3.1 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="gemini-3.1-pro-preview",
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: "gemini-3.1-pro-preview",
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": "gemini-3.1-pro-preview",
"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: "gemini-3.1-pro-preview",
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("gemini-3.1-pro-preview")
.addUserMessage("Summarize this diff")
.reasoningEffort(ReasoningEffort.MEDIUM)
.build());
System.out.println(resp.choices().get(0).message().content().orElse(""));About Gemini 3.1 Pro
Gemini 3.1 Pro (preview) is Google's refined iteration of the Gemini 3 Pro line, and its model page highlights better thinking, improved token efficiency, and a more grounded, factually consistent experience, with particular optimization for software engineering and agentic workflows that demand precise tool usage.
- It accepts text, image, video, audio, and PDF input in a 1,048,576-token context window with 65,536 output tokens, and supports function calling, structured outputs, code execution, grounding, and caching; a custom-tools variant prioritizes developer-defined tools.
- Synthorai fronts it with an OpenAI-compatible chat completions API.
Specs & limits
| Max output (vendor spec) | 65,536 |
| Modalities | text + image + video + audio → text |
| Features | tools · structured_output · streaming · vision · batch · caching · reasoning |
| Notable | 1,048,576-token input; Search/Maps grounding and code execution supported; image generation NOT supported despite gateway capability tag. |
| Prompt caching | automatic + explicit · min 1,024-token prefix |
FAQ
Is the Gemini 3.1 Pro 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 Gemini 3.1 Pro.
What is Gemini 3.1 Pro best at?
Better thinking and improved token efficiency, plus optimized for software engineering and agents and custom-tools variant prioritizes developer-defined tools. See the About section for the full picture from the vendor's own release notes.
How much does Gemini 3.1 Pro cost?
Gemini 3.1 Pro costs $2 per million input tokens and $12 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 Gemini 3.1 Pro support prompt caching?
Yes: automatic caching is on by default, with an explicit mode for guaranteed savings. Cached input tokens bill at $0.2/M vs $2/M uncached; prompts need a 1,024-token stable prefix to cache. Prompt caching guide →
How do I get access to Gemini 3.1 Pro?
Point your existing OpenAI SDK at base_url="https://synthorai.io/v1", set model="gemini-3.1-pro-preview", and you're done. One API key covers every model on the gateway.
What is Gemini 3.1 Pro's knowledge cutoff?
Gemini 3.1 Pro's knowledge cutoff is 2025-01, per the vendor's official documentation (as of 2026-07-09).