PDF to PDF in Node.js

Overview

Merge, split and modify PDF documents with the PDFCrowd Node.js client. The client handles communication with the API, while processing runs on PDFCrowd's servers.

Installation

Install the Node.js client with npm, or see other installation options.

npm install pdfcrowd

Quick Start

Update the input URLs and filenames as needed.

const pdfcrowd = require('pdfcrowd');

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

client.addPdfFile("cover.pdf");
client.addPdfFile("proposal.pdf");
client.addPdfFile("price.pdf");
client.addPdfFile("contact.pdf");
client.convertToFile("offer.pdf", (error) => {
    if (error) {
        console.error(error.toString());
        return;
    }
});

const pdfcrowd = require('pdfcrowd');

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

client.setPageWatermark("watermark.pdf");
client.addPdfFile("proposal.pdf");
client.convertToFile("company_offer.pdf", (error) => {
    if (error) {
        console.error(error.toString());
        return;
    }
});

const pdfcrowd = require('pdfcrowd');

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

client.setAction("extract");
client.setPageRange("3,7-");
client.addPdfFile("13_pages.pdf");
client.convertToFile("output.pdf", (error) => {
    if (error) {
        console.error(error.toString());
        return;
    }
});

Configure a Conversion

Authentication

Pass your PDFCrowd username and API key to PdfToPdfClient. Find your credentials on the API Keys page.

Add Input PDFs

Add each PDF before calling a conversion method. The default action joins the documents in the order they were added.

For encrypted input PDFs, set the document password with setInputPdfPassword() before conversion. This is separate from your API key and the passwords used to protect the output PDF.

Send PDF Bytes

Read two local PDFs as bytes, merge them in order, and save the result locally as merged.pdf:

const fs = require("node:fs");
const pdfcrowd = require("pdfcrowd");

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

client.addPdfRawData(fs.readFileSync("cover.pdf"));
client.addPdfRawData(fs.readFileSync("proposal.pdf"));
client.convertToFile("merged.pdf", (error) => {
    if (error) {
        console.error(error.toString());
        return;
    }
});

Add Conversion Settings

Set conversion options on the client before calling a conversion method. For example, client.setLinearize(true); optimizes the output PDF for progressive loading.

Common settings are listed below. See the method reference for all available options or browse Node.js examples.

Use "extract" with a page range to keep selected pages, or "delete" to remove them. The "shuffle" action interleaves pages from the input PDFs.

Handle the Result

Choose an Output

After adding the inputs and settings, choose how to receive the PDF:

Pipe the response stream to a writable stream or collect its chunks in a Buffer. The end callback runs when the response finishes.

This example merges two PDFs, collects the result in a Buffer, and saves it locally as merged.pdf:

const fs = require("node:fs");
const pdfcrowd = require("pdfcrowd");

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

client.addPdfFile("cover.pdf");
client.addPdfFile("proposal.pdf");
const chunks = [];
client.convert({
    data: (stream) => stream.on("data", (chunk) => chunks.push(chunk)),
    error: (message, statusCode) => {
        console.error(new pdfcrowd.Pdfcrowd.Error(String(message), statusCode).toString());
    },
    end: () => {
        const result = Buffer.concat(chunks);
        fs.writeFileSync("merged.pdf", result);
    }
});

When serving the result from a web application, use Content-Type: application/pdf.

Handle Errors

File-output methods pass a pdfcrowd.Pdfcrowd.Error to their callback on failure and null on success. Validation can also throw an exception. This example merges two PDFs and handles both paths, logging the HTTP status and reason code when available:

const pdfcrowd = require("pdfcrowd");

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

function handleError(error) {
    if (error instanceof pdfcrowd.Pdfcrowd.Error) {
        console.error("PDFCrowd error:", error.getStatusCode(),
            error.getReasonCode(), error.getMessage());
    } else {
        console.error(error);
    }
}

try {
    client.addPdfFile("cover.pdf");
    client.addPdfFile("proposal.pdf");
    client.convertToFile("merged.pdf", (error) => {
        if (error) {
            handleError(error);
            return;
        }
    });
} catch (error) {
    handleError(error);
}

Stream-output methods call error(message, statusCode) on failure. Local file and stream errors may need separate handling.

pdfcrowd.Pdfcrowd.Error provides these methods:

error.toString() returns the complete error, including available status and reason codes.

Common Status Codes

See all status and reason codes for specific explanations and Limits and Retries for retry behavior.

Read Conversion Information

This information is available after a conversion and describes the client's last conversion. Read it in the completion or error callback.

Limits and Retries

Request rate and concurrency limits depend on your license. Control how quickly your application submits conversions and how many it runs at once. A 429 response concerns request rate; a 430 response concerns requests already in progress. The maximum upload size is 300 MB.

The Node.js client automatically retries a request once when it receives HTTP 502 or 503. Use setRetryCount() to change that count, or set it to 0 to disable automatic retries. Account for these retries when adding an application-level retry policy.

Troubleshooting

Inspect a Conversion

This example merges two PDFs with debug logging enabled and logs the debug log URL when available. Use the input and settings from the conversion you are investigating.

const pdfcrowd = require("pdfcrowd");

const client = new pdfcrowd.PdfToPdfClient("demo", "demo");

function finish(error) {
    if (error) {
        console.error(error.toString());
    }
    const debugLogUrl = client.getDebugLogUrl();
    if (debugLogUrl) console.info("Debug log:", debugLogUrl);
}

try {
    client.addPdfFile("cover.pdf");
    client.addPdfFile("proposal.pdf");
    client.setDebugLog(true);
    client.convertToFile("merged.pdf", finish);
} catch (error) {
    finish(error);
}

The debug log contains conversion settings and processing details. You can also find logs in your conversion history. A local or connection failure may occur before a conversion log is available.

Common Problems

For help, contact support and include any available diagnostics, the client version, and enough detail to reproduce the problem.