curl --request POST \
  --url https://app.stockshift.io/api/v1/sales/invoices/{invoice}/send \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "contact_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}
'

import requests

url = "https://app.stockshift.io/api/v1/sales/invoices/{invoice}/send"

payload = { "contact_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a" }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://app.stockshift.io/api/v1/sales/invoices/{invoice}/send",
  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([
    'contact_id' => '3c90c3cc-0d44-4b50-8888-8dd25736052a'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($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://app.stockshift.io/api/v1/sales/invoices/{invoice}/send"

	payload := strings.NewReader("{\n  \"contact_id\": \"3c90c3cc-0d44-4b50-8888-8dd25736052a\"\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	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))

}

{
  "data": {
    "id": "<string>",
    "number": "<string>",
    "order_id": "<string>",
    "order_number": "<string>",
    "customer_id": "<string>",
    "customer_code": "<string>",
    "customer_name": "<string>",
    "status": "<string>",
    "issued_on": "<string>",
    "due_on": "<string>",
    "overdue": true,
    "tax_rounding": "<string>",
    "tax_exemption_reference": "<string>",
    "tax_needs_recalculation": true,
    "tax_partly_local": true,
    "subtotal": "<string>",
    "tax": "<string>",
    "total": "<string>",
    "paid": "<string>",
    "credited": "<string>",
    "outstanding": "<string>",
    "currency": "<string>",
    "note": "<string>",
    "issued_at": "<string>",
    "voided_at": "<string>",
    "sent_at": "<string>",
    "sent_to": "<string>",
    "created_at": "<string>",
    "lines": [
      "<unknown>"
    ],
    "payments": [
      "<unknown>"
    ],
    "credit_notes": [
      "<unknown>"
    ]
  }
}

{
  "type": "<string>",
  "title": "<string>",
  "status": 123,
  "code": "<string>",
  "detail": "<string>",
  "errors": {},
  "feature": "<string>",
  "reason": "<string>",
  "attempts_left": 123,
  "rule_ids": [
    "<string>"
  ],
  "witness": "<string>",
  "blind_recount": true,
  "flags": [
    {
      "flag": "<string>",
      "facts": {},
      "choices": [
        "<string>"
      ]
    }
  ]
}

{
  "type": "<string>",
  "title": "<string>",
  "status": 123,
  "code": "<string>",
  "detail": "<string>",
  "errors": {},
  "feature": "<string>",
  "reason": "<string>",
  "attempts_left": 123,
  "rule_ids": [
    "<string>"
  ],
  "witness": "<string>",
  "blind_recount": true,
  "flags": [
    {
      "flag": "<string>",
      "facts": {},
      "choices": [
        "<string>"
      ]
    }
  ]
}

{
  "type": "<string>",
  "title": "<string>",
  "status": 123,
  "code": "<string>",
  "detail": "<string>",
  "errors": {},
  "feature": "<string>",
  "reason": "<string>",
  "attempts_left": 123,
  "rule_ids": [
    "<string>"
  ],
  "witness": "<string>",
  "blind_recount": true,
  "flags": [
    {
      "flag": "<string>",
      "facts": {},
      "choices": [
        "<string>"
      ]
    }
  ]
}

{
  "type": "<string>",
  "title": "<string>",
  "status": 123,
  "code": "<string>",
  "detail": "<string>",
  "errors": {},
  "feature": "<string>",
  "reason": "<string>",
  "attempts_left": 123,
  "rule_ids": [
    "<string>"
  ],
  "witness": "<string>",
  "blind_recount": true,
  "flags": [
    {
      "flag": "<string>",
      "facts": {},
      "choices": [
        "<string>"
      ]
    }
  ]
}

{
  "type": "<string>",
  "title": "<string>",
  "status": 123,
  "code": "<string>",
  "detail": "<string>",
  "errors": {},
  "feature": "<string>",
  "reason": "<string>",
  "attempts_left": 123,
  "rule_ids": [
    "<string>"
  ],
  "witness": "<string>",
  "blind_recount": true,
  "flags": [
    {
      "flag": "<string>",
      "facts": {},
      "choices": [
        "<string>"
      ]
    }
  ]
}