curl --request POST \
  --url https://api.everhour.com/clients/{client_id}/invoices \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <api-key>' \
  --data '
{
  "limitDateFrom": "2019-03-11",
  "limitDateTill": "2019-03-13",
  "includeExpenses": true,
  "includeTime": true,
  "projects": [
    "gh:63301595"
  ],
  "tax": {
    "id": 123,
    "rate": 11
  },
  "discount": 25
}
'

import requests

url = "https://api.everhour.com/clients/{client_id}/invoices"

payload = {
    "limitDateFrom": "2019-03-11",
    "limitDateTill": "2019-03-13",
    "includeExpenses": True,
    "includeTime": True,
    "projects": ["gh:63301595"],
    "tax": {
        "id": 123,
        "rate": 11
    },
    "discount": 25
}
headers = {
    "X-Api-Key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'X-Api-Key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    limitDateFrom: '2019-03-11',
    limitDateTill: '2019-03-13',
    includeExpenses: true,
    includeTime: true,
    projects: ['gh:63301595'],
    tax: {id: 123, rate: 11},
    discount: 25
  })
};

fetch('https://api.everhour.com/clients/{client_id}/invoices', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.everhour.com/clients/{client_id}/invoices",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'limitDateFrom' => '2019-03-11',
    'limitDateTill' => '2019-03-13',
    'includeExpenses' => true,
    'includeTime' => true,
    'projects' => [
        'gh:63301595'
    ],
    'tax' => [
        'id' => 123,
        'rate' => 11
    ],
    'discount' => 25
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-Api-Key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.everhour.com/clients/{client_id}/invoices"

	payload := strings.NewReader("{\n  \"limitDateFrom\": \"2019-03-11\",\n  \"limitDateTill\": \"2019-03-13\",\n  \"includeExpenses\": true,\n  \"includeTime\": true,\n  \"projects\": [\n    \"gh:63301595\"\n  ],\n  \"tax\": {\n    \"id\": 123,\n    \"rate\": 11\n  },\n  \"discount\": 25\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-Api-Key", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api.everhour.com/clients/{client_id}/invoices")
  .header("X-Api-Key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"limitDateFrom\": \"2019-03-11\",\n  \"limitDateTill\": \"2019-03-13\",\n  \"includeExpenses\": true,\n  \"includeTime\": true,\n  \"projects\": [\n    \"gh:63301595\"\n  ],\n  \"tax\": {\n    \"id\": 123,\n    \"rate\": 11\n  },\n  \"discount\": 25\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.everhour.com/clients/{client_id}/invoices")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-Api-Key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"limitDateFrom\": \"2019-03-11\",\n  \"limitDateTill\": \"2019-03-13\",\n  \"includeExpenses\": true,\n  \"includeTime\": true,\n  \"projects\": [\n    \"gh:63301595\"\n  ],\n  \"tax\": {\n    \"id\": 123,\n    \"rate\": 11\n  },\n  \"discount\": 25\n}"

response = http.request(request)
puts response.read_body

{
  "id": 2660155,
  "client": {
    "id": 4567,
    "name": "Client Name",
    "projects": [
      "ev:1234567890"
    ],
    "businessDetails": "<string>",
    "budget": {
      "type": "money",
      "budget": 100000,
      "period": "general",
      "appliedFrom": "<string>",
      "disallowOverbudget": true,
      "excludeUnbillableTime": true,
      "excludeExpenses": true,
      "threshold": 123,
      "progress": 0
    }
  },
  "createdAt": "2018-01-16 12:42:59",
  "createdBy": {
    "id": 1304,
    "name": "User Name",
    "role": "admin",
    "status": "active",
    "headline": "CEO",
    "avatarUrl": "<string>",
    "phone": "<string>",
    "capacity": 123,
    "avatarUrlLarge": "<string>"
  },
  "status": "draft",
  "dateFrom": "<string>",
  "dateTill": "<string>",
  "dueDate": "<string>",
  "discount": {
    "amount": 4581,
    "rate": 25
  },
  "expenseMask": "%PROJECT% :: %CATEGORY%",
  "includeExpenses": true,
  "includeTime": true,
  "invoiceItems": [
    {
      "billedTime": 415860,
      "createdAt": "2017-02-22 16:11:33",
      "custom": false,
      "id": 52,
      "listAmount": 288793,
      "name": "Software Development",
      "netAmount": 288793,
      "position": 1,
      "taxable": 1,
      "totalAmount": 288793
    }
  ],
  "issueDate": "2019-03-22",
  "limitDateFrom": "<string>",
  "limitDateTill": "<string>",
  "listAmount": 18325,
  "netAmount": 13744,
  "projects": [
    "gh:63301595"
  ],
  "publicId": "1020",
  "tax": {
    "id": 123,
    "rate": 11,
    "amount": 1512
  },
  "timeMask": "%PROJECT%",
  "totalAmount": 15256,
  "totalTime": 43980,
  "valid": true
}