https://api.constructiononline.com/api/Invoices?Info={invoiceInfo}
This endpoint allows users to create a new invoice for a project in their ConstructionOnline company account. If successful, the endpoint will return a record of the newly created invoice. The new invoice will be automatically assigned a unique numerical ID called 'ID', which will be used for any future references. The required fields for this endpoint include PRJ_ID, CLIENT_ID, and ITEMS (NAME); all other properties are optional and can be entered during invoice creation.
Please note: invoices can only be created for existing projects in ConstructionOnline. If a specific project ID is not included in the request, the invoice creation will fail.
Requests
Info: JSON
- Properties to be added to the invoice.
- Required properties for the invoice: PRJ_ID, CLIENT_ID, ITEMS
- Required properties for the invoice ITEMS: NAME
- Allowed properties for the purchase order: TITLE, INV_DATE, RETAINAGE, STATUS, COM_PRORATED, NOTES, DUE_DATE, TERM_ID, TAX_INCLUDED, RETAINAGE_ENABLED, RETAINAGE_TYPE, RETAINAGE_INVOICE_ID
- Allowed properties for the purchase order ITEMS:
Individual properties for creation should be entered as JSON key-value pairs, as seen below:
{
"PRJ_ID": 1432504,
"CLIENT_ID": 906920,
"INV_DATE" : "2026-07-22T00:00:00",
"DUE_DATE" : "2026-07-31T00:00:00",
"ITEMS": [
{
"NAME" : "Labor",
"QTY" : 45.0,
"RATE" : 62.30
},
{
"NAME" : "Material",
"QTY" : 250.0,
"RATE" : 7.50
}
]
}
Example requests in cURL, C#, Python, and JavaScript can be found below:
cURL
# replace {email} with the email address for your ConstructionOnline account
# {password} with your ConstructionOnline password
# {apikey} with your provided API key
# {invoiceInfo} with the information for invoice creation
curl -X POST https://api.constructiononline.com/api/Invoices?Info={invoiceInfo} -u {email}:{password} -H 'APIKey:{apikey}'
C#
/* replace {username} with the email address for your ConstructionOnline account
{password} with your ConstructionOnline password
{apikey} with your provided API key
{invoiceInfo} with the information for invoice creation */
public string MakeRequest(string endpoint, string payload) {
string username = {username};
string password = {password};
string apiKey = {apikey};
string response = "";
var handler = new HttpClientHandler() { AutomaticDecompression = System.Net.DecompressionMethods.GZip };
using (HttpClient client = new HttpClient(handler)) {
client.BaseAddress = new Uri("http://api.constructiononline.com");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", System.Convert.ToBase64String(System.Text.Encoding.GetEncoding("ISO-8859-1").GetBytes(username + ":" + password)));
client.DefaultRequestHeaders.Add("APIKey", apiKey);
client.DefaultRequestHeaders.Add("Accept-Encoding", "gzip");
HttpContent content = new StringContent(payload, System.Text.Encoding.UTF32, "application/json");
response = client.PostAsync(endpoint, content).Result.ToString();
}
return response;
}
MakeRequest("api/Invoices?Info={invoiceInfo}");
Python
#replace {username} with the email address for your ConstructionOnline account
#{password} with your ConstructionOnline password
#{apikey} with your provided API key
#{invoiceInfo} with the information for invoice creation
import base64, requests, json
#Global Variables
apikey = {apikey}
username = {username}
password = {password}
#Functions
def makeRequest(endpoint, payload):
url = "https://api.constructiononline.com/" + endpoint
userPass = username + ":" + password
headers = {
"APIKey": apikey,
"Accept-Encoding": "gzip, deflate, br",
"Authorization": "Basic " + base64.b64encode(userPass.encode()).decode(),
}
response = requests.request("POST", url, headers=headers, data=payload)
return json.dumps(json.loads(response.text), indent=2)
#Main Program
print(makeRequest("api/Invoices?Info={invoiceInfo}"))
JavaScript
/* replace {username} with the email address for your ConstructionOnline account
{password} with your ConstructionOnline password
{apikey} with your provided API key
{invoiceInfo} with the information for invoice creation */
username = '{username}';
password = '{password}';
apikey = '{apikey}';
function makeRequest(endpoint, payload) {
auth = btoa('${username}:${password}');
var myHeaders = new Headers();
myHeaders.append("APIKey", apikey);
myHeaders.append("Accept-Encoding", "gzip, deflate, br");
myHeaders.append("Authorization", "Basic ${auth}");
var requestOptions = {
method: 'POST',
body: '',
headers: myHeaders,
redirect: 'follow'
};
fetch("https://api.constructiononline.com/" + endpoint, requestOptions)
.then(response => response.text())
.then(result => console.log(result))
.catch(error => console.log('error', error));
return response;
};
makeRequest("api/Invoices?Info={invoiceInfo}");
Responses
200: Success
A successful request will return a 200 response with a record of the edited invoice in the body, as seen below.
{
"ID": 34313,
"PRJ_ID": 1432504,
"INV_NUMBER": "0",
"INV_DATE": "2024-09-26T05:00:00",
"TOTAL": 1391283.9700000002,
"RETAINAGE": 0.0,
"LMOD": "2026-04-06T18:10:24.783",
"STATUS": 2,
"ACCT_INT_ID": "173",
"SENT_TO_ACCT_INT_VALUE": 1391283.97,
"SENT_TO_ACCT_INT_COM": 0.0,
"COMPANY_ID": 23573,
"CORDER_ID": 0,
"COM_PRORATED": true,
"DATE_CREATED": "2024-09-26T16:40:24.67",
"CREATED_BY": 885048,
"LMOD_BY": 885048,
"ACCT_INT_SENT_DATE": "2025-09-09T15:29:22.167",
"PAID_AMOUNT": 0.0,
"PAID_DATE": "2026-04-06T18:10:24.783",
"TITLE": "Pre-Construction Fees",
"NOTES": "",
"DUE_DATE": "2024-09-26T05:00:00",
"CLIENT_ID": 906920,
"TERM_ID": 0,
"TOTAL_COM": 0.0,
"FROM_ACCT_INT": false,
"DATE_EMAILED": null,
"REFERENCE_ID": "1432504-001",
"TAX_INCLUDED": true,
"CREATION_SOURCE": 0,
"AGGREGATE_BILLABLE": false,
"RETAINAGE_ENABLED": false,
"RETAINAGE_TYPE": 0,
"RETAINAGE_INVOICE_ID": null,
"PAYMENT_APPLICATION_ID": 161,
"ATTACHIDS": null,
"ATTACHMENTS": null,
"ITEMS": [
{
"ID": 246078,
"PRJ_ID": 1432504,
"INV_ID": 34313,
"NAME": "Div 01 Gen. Requirements:01000 - General Conditions",
"DESCRIPTION": "",
"TOTAL": 53270.3,
"RETAINAGE": 0.0,
"MARGIN": 0.0,
"QTY": 1.0,
"RATE": 53270.3,
"ITEM_ID": 32992293,
"ITEM_TYPE": 2,
"PAID_AMOUNT": 53270.3,
"TAX_TYPE": 0,
"TAX_PERCENT": 0.0,
"MARKUP_TYPE": 0,
"MARKUP": 0.0
},
...
],
"TERMS": [
{
"ID": 2,
"NAME": "net30",
"COMPANY_ID": 0,
"DAY_OF_MONTH_DUE": null,
"DUE_NEXT_MONTH_DAYS": null,
"DUE_DAYS": 30,
"TYPE": "STANDARD",
"IS_DEFAULT": true,
"DATE_CREATED": "2020-09-28T12:39:51.92",
"LMOD": "2020-09-28T12:39:51.92",
"LMOD_BY": 0,
"CREATED_BY": null
}
]
}
404: Error
The server was not able to locate the resource specified in the request.
429: Error
The user has surpassed the request rate limit for the hour, day, week, or month.
500: Error
There was an internal server error and the server was unable to complete the request.
Last updated: July 22, 2026