Examples by language

# FD_API=https://sandbox-app.facturadigital.com.mx/api/v5
curl -sS -X POST "$FD_API/invoice/create" \
  -H "X-Api-Key: $FD_API_KEY" \
  --data-urlencode "json@invoice.json"

<?php
// Read the key from an environment variable; never put it in the code.
$ch = curl_init(getenv('FD_API') . '/invoice/create');
curl_setopt_array($ch, [
    CURLOPT_POST           => true,
    CURLOPT_HTTPHEADER     => ['X-Api-Key: ' . getenv('FD_API_KEY')],
    CURLOPT_POSTFIELDS     => http_build_query(['json' => file_get_contents('invoice.json')]),
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_TIMEOUT        => 60,
]);
$res  = json_decode(curl_exec($ch), true);
$http = curl_getinfo($ch, CURLINFO_HTTP_CODE);

if ($http === 200 && ($res['code'] ?? null) == 200) {
    echo "Stamped: " . $res['cfdi']['UUID'] . PHP_EOL;
} else {
    echo "Rejected ({$res['code']}): {$res['message']}" . PHP_EOL;
}

// Read the key from an environment variable; never put it in the code.
import { readFile } from "node:fs/promises";

const res = await fetch(`${process.env.FD_API}/invoice/create`, {
  method: "POST",
  headers: { "X-Api-Key": process.env.FD_API_KEY },
  body: new URLSearchParams({ json: await readFile("invoice.json", "utf8") }),
  signal: AbortSignal.timeout(60_000),
});
const body = await res.json();

if (res.ok && body.code == 200) {
  console.log("Stamped:", body.cfdi.UUID);
} else {
  console.log(`Rejected (${body.code}): ${body.message}`);
}

# Read the key from an environment variable; never put it in the code.
import os, requests

with open("invoice.json", encoding="utf-8") as f:
    r = requests.post(
        f"{os.environ['FD_API']}/invoice/create",
        headers={"X-Api-Key": os.environ["FD_API_KEY"]},
        data={"json": f.read()},
        timeout=60,
    )
body = r.json()

if r.status_code == 200 and str(body.get("code")) == "200":
    print("Stamped:", body["cfdi"]["UUID"])
else:
    print(f"Rejected ({body.get('code')}): {body.get('message')}")

// Read the key from an environment variable; never put it in the code.
using System.Net.Http.Json;
using System.Text.Json;

var api = Environment.GetEnvironmentVariable("FD_API");
using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(60) };
http.DefaultRequestHeaders.Add("X-Api-Key", Environment.GetEnvironmentVariable("FD_API_KEY"));

var form = new FormUrlEncodedContent(new Dictionary<string, string> {
    ["json"] = await File.ReadAllTextAsync("invoice.json")
});
var res = await http.PostAsync($"{api}/invoice/create", form);
var body = await res.Content.ReadFromJsonAsync<JsonElement>();

if (res.IsSuccessStatusCode && body.GetProperty("code").ToString() == "200")
    Console.WriteLine($"Stamped: {body.GetProperty("cfdi").GetProperty("UUID")}");
else
    Console.WriteLine($"Rejected ({body.GetProperty("code")}): {body.GetProperty("message")}");

// Read the key from an environment variable; never put it in the code.
import java.net.URI;
import java.net.URLEncoder;
import java.net.http.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.*;
import java.time.Duration;

var json = Files.readString(Path.of("invoice.json"));
var req = HttpRequest.newBuilder(URI.create(System.getenv("FD_API") + "/invoice/create"))
    .timeout(Duration.ofSeconds(60))
    .header("X-Api-Key", System.getenv("FD_API_KEY"))
    .header("Content-Type", "application/x-www-form-urlencoded")
    .POST(HttpRequest.BodyPublishers.ofString("json=" + URLEncoder.encode(json, StandardCharsets.UTF_8)))
    .build();
var res = HttpClient.newHttpClient().send(req, HttpResponse.BodyHandlers.ofString());

// res.statusCode() is 200 if it was stamped; the UUID is in cfdi.UUID of the body.
// With 400, code and message say why (read them with your JSON library).
System.out.println(res.statusCode() + " " + res.body());

curl -sS "$FD_API/account/balance" -H "X-Api-Key: $FD_API_KEY"

const res = await fetch(`${process.env.FD_API}/account/balance`, {
  headers: { "X-Api-Key": process.env.FD_API_KEY },
});
const { balance } = await res.json();

r = requests.get(f"{os.environ['FD_API']}/account/balance",
                 headers={"X-Api-Key": os.environ["FD_API_KEY"]}, timeout=30)
balance = r.json()["balance"]

$ch = curl_init(getenv('FD_API') . '/account/balance');
curl_setopt_array($ch, [
    CURLOPT_HTTPHEADER     => ['X-Api-Key: ' . getenv('FD_API_KEY')],
    CURLOPT_RETURNTRANSFER => true,
]);
$balance = json_decode(curl_exec($ch), true)['balance'];

curl -sS -X POST "$FD_API/invoice/cancel" \
  -H "X-Api-Key: $FD_API_KEY" \
  -H "UUID: 6FA90F39-2D7A-4F1C-9B3E-5C1D8A0E7B42" \
  -H "MOTIVO: 02"

const res = await fetch(`${process.env.FD_API}/invoice/cancel`, {
  method: "POST",
  headers: {
    "X-Api-Key": process.env.FD_API_KEY,
    UUID: "6FA90F39-2D7A-4F1C-9B3E-5C1D8A0E7B42",
    MOTIVO: "02",
  },
});
const body = await res.json(); // code 200 = the SAT accepted the request

r = requests.post(f"{os.environ['FD_API']}/invoice/cancel", headers={
    "X-Api-Key": os.environ["FD_API_KEY"],
    "UUID": "6FA90F39-2D7A-4F1C-9B3E-5C1D8A0E7B42",
    "MOTIVO": "02",
}, timeout=60)
body = r.json()  # code 200 = the SAT accepted the request

$ch = curl_init(getenv('FD_API') . '/invoice/cancel');
curl_setopt_array($ch, [
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => '',
    CURLOPT_HTTPHEADER     => [
        'X-Api-Key: ' . getenv('FD_API_KEY'),
        'UUID: 6FA90F39-2D7A-4F1C-9B3E-5C1D8A0E7B42',
        'MOTIVO: 02',
    ],
    CURLOPT_RETURNTRANSFER => true,
]);
$body = json_decode(curl_exec($ch), true); // code 200 = the SAT accepted the request