Invoice PDF API — invoices straight from JSON

Send line items and parties as JSON; get back a finished, correctly-totalled PDF.

/// Quick answer

An invoice PDF API turns structured data — buyer, seller, line items, totals — into a finished PDF in a single HTTP request, with no template to open and no document to lay out. ASHDOCS does it at POST /api/v1/tools/invoice-pdf for one credit, and a free version runs in the browser without an account.

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How does the Invoice PDF API work?

One HTTP request from any language. Every ASHDOCS endpoint uses the same X-API-Key header.

How to use this endpoint →

curl -X POST https://www.ashdocs.com/api/v1/tools/invoice-pdf \
  -H "X-API-Key: ash_live_..." \
  -H "Content-Type: application/json" \
  -d '{"invoice":{"number":"INV-2026-0041","currency":"USD","seller":{"name":"Acme Studio"},"buyer":{"name":"Globex Ltd"},"line_items":[{"description":"Design work","quantity":12,"unit_price":95,"tax_rate":0}]},"options":{"template":"clean","format":"A4"}}'

import requests

r = requests.post(
    "https://www.ashdocs.com/api/v1/tools/invoice-pdf",
    headers={"X-API-Key": "ash_live_..."},
    json={
        "invoice": {
            "number": "INV-2026-0041",
            "currency": "USD",
            "seller": {
                "name": "Acme Studio"
            },
            "buyer": {
                "name": "Globex Ltd"
            },
            "line_items": [
                {
                    "description": "Design work",
                    "quantity": 12,
                    "unit_price": 95,
                    "tax_rate": 0
                }
            ]
        },
        "options": {
            "template": "clean",
            "format": "A4"
        }
    },
)
job = r.json()
print(job["status"], job["output_files"][0]["url"])

const res = await fetch("https://www.ashdocs.com/api/v1/tools/invoice-pdf", {
  method: "POST",
  headers: { "X-API-Key": "ash_live_...", "Content-Type": "application/json" },
  body: JSON.stringify({"invoice":{"number":"INV-2026-0041","currency":"USD","seller":{"name":"Acme Studio"},"buyer":{"name":"Globex Ltd"},"line_items":[{"description":"Design work","quantity":12,"unit_price":95,"tax_rate":0}]},"options":{"template":"clean","format":"A4"}}),
});
const job = await res.json();
console.log(job.status, job.output_files[0].url);

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("X-API-Key", "ash_live_...");

var body = new StringContent(
    "{\"invoice\":{\"number\":\"INV-2026-0041\",\"currency\":\"USD\",\"seller\":{\"name\":\"Acme Studio\"},\"buyer\":{\"name\":\"Globex Ltd\"},\"line_items\":[{\"description\":\"Design work\",\"quantity\":12,\"unit_price\":95,\"tax_rate\":0}]},\"options\":{\"template\":\"clean\",\"format\":\"A4\"}}",
    Encoding.UTF8, "application/json");

var res = await client.PostAsync("https://www.ashdocs.com/api/v1/tools/invoice-pdf", body);
var job = await res.Content.ReadAsStringAsync();
Console.WriteLine(job);

import java.io.ByteArrayOutputStream;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;

public class Sample {
  public static void main(String[] args) throws Exception {
    String json = "{\"invoice\":{\"number\":\"INV-2026-0041\",\"currency\":\"USD\",\"seller\":{\"name\":\"Acme Studio\"},\"buyer\":{\"name\":\"Globex Ltd\"},\"line_items\":[{\"description\":\"Design work\",\"quantity\":12,\"unit_price\":95,\"tax_rate\":0}]},\"options\":{\"template\":\"clean\",\"format\":\"A4\"}}";
    HttpRequest req = HttpRequest.newBuilder(URI.create("https://www.ashdocs.com/api/v1/tools/invoice-pdf"))
        .header("X-API-Key", "ash_live_...")
        .header("Content-Type", "application/json")
        .POST(HttpRequest.BodyPublishers.ofString(json))
        .build();
    HttpResponse<String> res = HttpClient.newHttpClient().send(req, HttpResponse.BodyHandlers.ofString());
    System.out.println(res.body());
  }
}

#include <stdio.h>
#include <curl/curl.h>

int main(void) {
  CURL *curl = curl_easy_init();
  if (!curl) return 1;
  struct curl_slist *headers = NULL;
  headers = curl_slist_append(headers, "X-API-Key: ash_live_...");
  headers = curl_slist_append(headers, "Content-Type: application/json");
  curl_easy_setopt(curl, CURLOPT_POSTFIELDS, "{\"invoice\":{\"number\":\"INV-2026-0041\",\"currency\":\"USD\",\"seller\":{\"name\":\"Acme Studio\"},\"buyer\":{\"name\":\"Globex Ltd\"},\"line_items\":[{\"description\":\"Design work\",\"quantity\":12,\"unit_price\":95,\"tax_rate\":0}]},\"options\":{\"template\":\"clean\",\"format\":\"A4\"}}");
  curl_easy_setopt(curl, CURLOPT_URL, "https://www.ashdocs.com/api/v1/tools/invoice-pdf");
  curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
  CURLcode rc = curl_easy_perform(curl);
  printf("\n");
  curl_slist_free_all(headers);
  curl_easy_cleanup(curl);
  return rc == CURLE_OK ? 0 : 1;
}

Common use cases

→Auto-invoice on Stripe payment or Shopify order
→Monthly billing runs from a cron
→Invoices from CRM or project-management triggers

Frequently asked questions

Does the invoice PDF API calculate sales tax for me?+

No. It applies the rate you supply and computes the totals from it. It does not determine which rate applies to your transaction.

How much does one invoice cost?+

One credit.

Who calculates the totals?+

The server does. The line total, the subtotal, the tax per rate and the grand total are all computed from the quantities, unit prices and tax rates you send — the client cannot override them, and a total supplied in the payload is ignored.

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