One API.
The same balance as StarKerak.

API="https://paystars.uz/api/v1"
ORDER_KEY="stars_$(uuidgen)"
VERIFY=$(curl --fail-with-body -sS -X POST "$API/check-username" \
  -H "X-API-Key: $PAYSTARS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"username":"telegram","kind":"stars"}')
TOKEN=$(printf '%s' "$VERIFY" | jq -r '.verification_token')

curl --fail-with-body -sS -X POST "$API/stars/buy" \
  -H "X-API-Key: $PAYSTARS_API_KEY" \
  -H "Idempotency-Key: $ORDER_KEY" \
  -H "Content-Type: application/json" \
  -d "{\"username\":\"telegram\",\"quantity\":100,\"verification_token\":\"$TOKEN\",\"currency\":\"USD\"}"

import { randomUUID } from 'node:crypto';

const base = 'https://paystars.uz/api/v1';
const headers = { 'X-API-Key': process.env.PAYSTARS_API_KEY, 'Content-Type': 'application/json' };
const verify = await fetch(`${base}/check-username`, {
  method: 'POST', headers, body: JSON.stringify({ username: 'telegram', kind: 'stars' })
}).then(async r => { if (!r.ok) throw new Error(await r.text()); return r.json(); });

const order = await fetch(`${base}/stars/buy`, {
  method: 'POST', headers: { ...headers, 'Idempotency-Key': `stars_${randomUUID()}` },
  body: JSON.stringify({ username: verify.username, quantity: 100, verification_token: verify.verification_token, currency: 'USD' })
}).then(async r => { if (!r.ok) throw new Error(await r.text()); return r.json(); });
console.log(order.order_id, order.status);

import os, uuid, requests

base = "https://paystars.uz/api/v1"
headers = {"X-API-Key": os.environ["PAYSTARS_API_KEY"]}
verify = requests.post(f"{base}/check-username", headers=headers,
    json={"username": "telegram", "kind": "premium"}, timeout=15)
verify.raise_for_status()
recipient = verify.json()

order = requests.post(f"{base}/premium/buy", headers={
    **headers, "Idempotency-Key": f"premium_{uuid.uuid4()}"
}, json={"username": recipient["username"], "months": 3,
         "verification_token": recipient["verification_token"], "currency": "USD"}, timeout=20)
order.raise_for_status()
print(order.json())

<?php
$base = 'https://paystars.uz/api/v1';
$key = getenv('PAYSTARS_API_KEY');
function postJson($url, $headers, $body) {
  $ch = curl_init($url);
  curl_setopt_array($ch, [CURLOPT_RETURNTRANSFER => true, CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => $headers, CURLOPT_POSTFIELDS => json_encode($body), CURLOPT_TIMEOUT => 20]);
  $raw = curl_exec($ch); $status = curl_getinfo($ch, CURLINFO_HTTP_CODE); curl_close($ch);
  if ($status < 200 || $status >= 300) throw new RuntimeException($raw);
  return json_decode($raw, true, flags: JSON_THROW_ON_ERROR);
}
$common = ["X-API-Key: $key", 'Content-Type: application/json'];
$user = postJson("$base/check-username", $common, ['username' => 'telegram', 'kind' => 'stars']);
$order = postJson("$base/stars/buy", [...$common, 'Idempotency-Key: stars_'.bin2hex(random_bytes(16))],
  ['username' => $user['username'], 'quantity' => 100, 'verification_token' => $user['verification_token'], 'currency' => 'USD']);
print_r($order);

package main

import ("bytes"; "encoding/json"; "fmt"; "io"; "net/http"; "os"; "github.com/google/uuid")
func post(path string, body any, idempotency string, out any) error {
  data, _ := json.Marshal(body)
  req, _ := http.NewRequest("POST", "https://paystars.uz/api/v1"+path, bytes.NewReader(data))
  req.Header.Set("X-API-Key", os.Getenv("PAYSTARS_API_KEY")); req.Header.Set("Content-Type", "application/json")
  if idempotency != "" { req.Header.Set("Idempotency-Key", idempotency) }
  res, err := http.DefaultClient.Do(req); if err != nil { return err }; defer res.Body.Close()
  if res.StatusCode >= 300 { raw, _ := io.ReadAll(res.Body); return fmt.Errorf("API %d: %s", res.StatusCode, raw) }
  return json.NewDecoder(res.Body).Decode(out)
}
func main() {
  var user struct { Username string `json:"username"`; VerificationToken string `json:"verification_token"` }
  if err := post("/check-username", map[string]any{"username":"telegram", "kind":"stars"}, "", &user); err != nil { panic(err) }
  var order map[string]any
  if err := post("/stars/buy", map[string]any{"username":user.Username, "quantity":100,
    "verification_token":user.VerificationToken, "currency":"USD"}, "stars_"+uuid.NewString(), &order); err != nil { panic(err) }
  fmt.Println(order)
}