API reference

Receipts

A paid invoice has a receipt. Read it, or create a signed link to its PDF for your customer.

Endpoint	What it does
GET `/api/v1/receipts/{invoiceId}`	Get a receipt
POST `/api/v1/receipts/{invoiceId}/links`	Create a receipt link

Receipts are addressed by the paid invoice's id. Asking for an unpaid invoice's receipt gets 404 not_paid; wait for invoice.paid or receipt.issued.

The receipt object#

The receipt for a paid invoice.

Field	Description
invoiceIdinteger	The paid invoice.
invoiceNumberstring	The invoice number.
customerIdinteger	The customer.
currencystring	ISO currency code. One of `NGN`, `USD`, `CAD`, `EUR`, `GBP`.
amountnumber (decimal)	The invoice total.
paidAttimestamp · nullable	When it was paid. Server time, no offset.
paymentMethodstring · nullable	`online` or `offline`.

Receipt

{
  "invoiceId": 5012,
  "invoiceNumber": "MAX-2026-0042",
  "customerId": 812,
  "currency": "NGN",
  "amount": 860000.00,
  "paidAt": "2026-11-03T14:02:00",
  "paymentMethod": "online"
}

Get a receipt#

GET/api/v1/receipts/{invoiceId}invoices:read

Returns the receipt for a paid invoice.

Path parameters

Field	Description
invoiceIdinteger	required The paid invoice's id.

Request

curl "$FLUX_BASE_URL/api/v1/receipts/5012" \
  -H "Authorization: ApiKey $FLUX_API_KEY"

// Node.js 18+ (built-in fetch). Save as an .mjs file.
const response = await fetch(`${process.env.FLUX_BASE_URL}/api/v1/receipts/5012`, {
  headers: {
    Authorization: `ApiKey ${process.env.FLUX_API_KEY}`,
  },
});
console.log(response.status, await response.json());

import os

import requests

response = requests.get(
    f"{os.environ['FLUX_BASE_URL']}/api/v1/receipts/5012",
    headers={"Authorization": f"ApiKey {os.environ['FLUX_API_KEY']}"},
    timeout=30,
)
print(response.status_code, response.json())

<?php
$ch = curl_init(getenv('FLUX_BASE_URL') . '/api/v1/receipts/5012');
curl_setopt_array($ch, [
    CURLOPT_HTTPHEADER => [
        'Authorization: ApiKey ' . getenv('FLUX_API_KEY'),
    ],
    CURLOPT_RETURNTRANSFER => true,
]);
$response = curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_HTTP_CODE), ' ', $response, PHP_EOL;

using System.Net.Http.Headers;

var baseUrl = Environment.GetEnvironmentVariable("FLUX_BASE_URL");
using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization =
    new AuthenticationHeaderValue("ApiKey", Environment.GetEnvironmentVariable("FLUX_API_KEY"));

using var request = new HttpRequestMessage(HttpMethod.Get, $"{baseUrl}/api/v1/receipts/5012");

using var response = await http.SendAsync(request);
Console.WriteLine($"{(int)response.StatusCode} {await response.Content.ReadAsStringAsync()}");

package main

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

func main() {
	req, err := http.NewRequest("GET", os.Getenv("FLUX_BASE_URL")+"/api/v1/receipts/5012", nil)
	if err != nil {
		panic(err)
	}
	req.Header.Set("Authorization", "ApiKey "+os.Getenv("FLUX_API_KEY"))

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer resp.Body.Close()
	out, _ := io.ReadAll(resp.Body)
	fmt.Println(resp.StatusCode, string(out))
}

Responses

200 OK

{
  "invoiceId": 5012,
  "invoiceNumber": "MAX-2026-0042",
  "customerId": 812,
  "currency": "NGN",
  "amount": 860000.00,
  "paidAt": "2026-11-03T14:02:00",
  "paymentMethod": "online"
}

5 possible errors

Status	Code	When
`404`	`not_found`	Unknown id, or an id that belongs to another organization.
`404`	`not_paid`	You asked for the receipt of an unpaid invoice.
`401`	`unauthorized`	No API key, an unknown key or a revoked key.
`403`	`insufficient_scope`	The key lacks the scope. `details` names it: `{ "required": "invoices:write" }`.
`429`	`rate_limited`	Too many requests for this key. Wait for the `Retry-After` seconds.

Create a receipt link#

POST/api/v1/receipts/{invoiceId}/linksinvoices:read

Returns a signed link to the receipt PDF. payUrl is always null here.

Path parameters

Field	Description
invoiceIdinteger	required The paid invoice's id.

Request

curl -X POST "$FLUX_BASE_URL/api/v1/receipts/5012/links" \
  -H "Authorization: ApiKey $FLUX_API_KEY"

// Node.js 18+ (built-in fetch). Save as an .mjs file.
const response = await fetch(`${process.env.FLUX_BASE_URL}/api/v1/receipts/5012/links`, {
  method: "POST",
  headers: {
    Authorization: `ApiKey ${process.env.FLUX_API_KEY}`,
  },
});
console.log(response.status, await response.json());

import os

import requests

response = requests.post(
    f"{os.environ['FLUX_BASE_URL']}/api/v1/receipts/5012/links",
    headers={"Authorization": f"ApiKey {os.environ['FLUX_API_KEY']}"},
    timeout=30,
)
print(response.status_code, response.json())

<?php
$ch = curl_init(getenv('FLUX_BASE_URL') . '/api/v1/receipts/5012/links');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_HTTPHEADER => [
        'Authorization: ApiKey ' . getenv('FLUX_API_KEY'),
    ],
    CURLOPT_RETURNTRANSFER => true,
]);
$response = curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_HTTP_CODE), ' ', $response, PHP_EOL;

using System.Net.Http.Headers;

var baseUrl = Environment.GetEnvironmentVariable("FLUX_BASE_URL");
using var http = new HttpClient();
http.DefaultRequestHeaders.Authorization =
    new AuthenticationHeaderValue("ApiKey", Environment.GetEnvironmentVariable("FLUX_API_KEY"));

using var request = new HttpRequestMessage(HttpMethod.Post, $"{baseUrl}/api/v1/receipts/5012/links");

using var response = await http.SendAsync(request);
Console.WriteLine($"{(int)response.StatusCode} {await response.Content.ReadAsStringAsync()}");

package main

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

func main() {
	req, err := http.NewRequest("POST", os.Getenv("FLUX_BASE_URL")+"/api/v1/receipts/5012/links", nil)
	if err != nil {
		panic(err)
	}
	req.Header.Set("Authorization", "ApiKey "+os.Getenv("FLUX_API_KEY"))

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer resp.Body.Close()
	out, _ := io.ReadAll(resp.Body)
	fmt.Println(resp.StatusCode, string(out))
}

Responses

200 OK

{
  "pdfUrl": "https://api.flux.example/public/receipts/NDIuNTAxMi5ycC4xNzk2MTE2NDAw.Zt4hQ1vB8kW0mXc3sR7eLp2yN6uGaJ9oFdKiT5wHqEs/pdf",
  "payUrl": null,
  "expiresAt": "2026-12-01T10:00:00.5236411Z"
}

6 possible errors

Status	Code	When
`404`	`not_found`	Unknown id, or an id that belongs to another organization.
`404`	`not_paid`	You asked for the receipt of an unpaid invoice.
`503`	`links_not_configured`	The server has no link-signing key configured.
`401`	`unauthorized`	No API key, an unknown key or a revoked key.
`403`	`insufficient_scope`	The key lacks the scope. `details` names it: `{ "required": "invoices:write" }`.
`429`	`rate_limited`	Too many requests for this key. Wait for the `Retry-After` seconds.