Chat Completions (non-streaming)

cURL

curl https://api.fastapi.ai/v1/chat/completions \
  -H "Authorization: Bearer $FAST_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o-mini",
    "messages": [
      {"role": "user", "content": "Say hello in one short sentence."}
    ]
  }'

JavaScript (Node)

const res = await fetch('https://api.fastapi.ai/v1/chat/completions', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.FAST_API_KEY}`,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    model: 'gpt-4o-mini',
    messages: [{ role: 'user', content: 'Say hello in one short sentence.' }],
  }),
});

console.log(await res.json());

Python

import os
import requests

resp = requests.post(
  "https://api.fastapi.ai/v1/chat/completions",
  headers={
    "Authorization": f"Bearer {os.environ['FAST_API_KEY']}",
    "Content-Type": "application/json",
  },
  json={
    "model": "gpt-4o-mini",
    "messages": [{"role": "user", "content": "Say hello in one short sentence."}],
  },
)

print(resp.json())

Go

package main

import (
  "bytes"
  "encoding/json"
  "fmt"
  "io"
  "net/http"
  "os"
)

func main() {
  payload := map[string]any{
    "model": "gpt-4o-mini",
    "messages": []map[string]any{{
      "role": "user",
      "content": "Say hello in one short sentence.",
    }},
  }
  b, _ := json.Marshal(payload)

  req, _ := http.NewRequest("POST", "https://api.fastapi.ai/v1/chat/completions", bytes.NewReader(b))
  req.Header.Set("Authorization", "Bearer "+os.Getenv("FAST_API_KEY"))
  req.Header.Set("Content-Type", "application/json")

  resp, err := http.DefaultClient.Do(req)
  if err != nil {
    panic(err)
  }
  defer resp.Body.Close()

  body, _ := io.ReadAll(resp.Body)
  fmt.Println(string(body))
}

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
  public static void main(String[] args) throws Exception {
    String body = "{\"model\":\"gpt-4o-mini\",\"messages\":[{\"role\":\"user\",\"content\":\"Say hello in one short sentence.\"}]}";

    HttpRequest req = HttpRequest.newBuilder()
      .uri(URI.create("https://api.fastapi.ai/v1/chat/completions"))
      .header("Authorization", "Bearer " + System.getenv("FAST_API_KEY"))
      .header("Content-Type", "application/json")
      .POST(HttpRequest.BodyPublishers.ofString(body))
      .build();

    HttpResponse<String> resp = HttpClient.newHttpClient().send(req, HttpResponse.BodyHandlers.ofString());
    System.out.println(resp.body());
  }
}