Convert a Base64-Encoded Image to PDF in JavaScript Using PDF.co

Step 1: Prepare Your Project

Install a supported Node.js version. Create a project folder and run:

npm init -y
npm install axios

Save your image’s Base64 content in a text file named image-base64.txt. It can contain either raw Base64 or a data URL such as data:image/png;base64,....

Step 2: Add the JavaScript Code

Create index.js and paste the following code.

Replace the API key placeholder with your key from the PDF.co dashboard. Set IMAGE_NAME to match the encoded image’s format.

const axios = require("axios");
const fs = require("node:fs/promises");
const { setTimeout: delay } = require("node:timers/promises");

const API_KEY = "YOUR_PDFCO_API_KEY";
const INPUT_FILE = "image-base64.txt";
const IMAGE_NAME = "source.png"; // Use source.jpg for a JPEG.
const OUTPUT_FILE = "result.pdf";

const api = axios.create({
  baseURL: "https://api.pdf.co/v1",
  headers: {
    "x-api-key": API_KEY,
    "Content-Type": "application/json"
  },
  timeout: 60000
});

async function post(path, payload) {
  const { data } = await api.post(path, payload);

  if (data.error) {
    throw new Error(data.message || `Request failed: ${path}`);
  }

  return data;
}

async function waitForResult(jobId, initialUrl) {
  for (let attempt = 0; attempt < 60; attempt++) {
    await delay(3000);

    const result = await post("/job/check", { jobid: jobId });

    if (result.status === "success") {
      const url = result.url || initialUrl;

      if (!url) {
        throw new Error("The completed job has no output URL.");
      }

      return url;
    }

    if (result.status !== "working") {
      throw new Error(
        result.message || `Job ended with status: ${result.status}`
      );
    }
  }

  throw new Error(
    `Stopped waiting for job ${jobId}. The server job may still be running.`
  );
}

async function main() {
  const input = (await fs.readFile(INPUT_FILE, "utf8")).trim();

  const base64 = input
    .replace(/^data:image\/[^;]+;base64,/i, "")
    .replace(/\s/g, "");

  if (!base64) {
    throw new Error("The input file contains no Base64 data.");
  }

  const uploaded = await post("/file/upload/base64", {
    file: base64,
    name: IMAGE_NAME
  });

  if (!uploaded.url) {
    throw new Error("The upload returned no file URL.");
  }

  const conversion = await post("/pdf/convert/from/image", {
    url: uploaded.url,
    name: OUTPUT_FILE,
    async: true
  });

  if (!conversion.jobId) {
    throw new Error("The conversion returned no job ID.");
  }

  console.log(`Processing job: ${conversion.jobId}`);

  const outputUrl = await waitForResult(
    conversion.jobId,
    conversion.url
  );

  // Download without sending the PDF.co API key to the file server.
  const download = await axios.get(outputUrl, {
    responseType: "arraybuffer",
    timeout: 60000
  });

  await fs.writeFile(OUTPUT_FILE, Buffer.from(download.data), {
    flag: "wx"
  });

  console.log(`Saved ${OUTPUT_FILE}`);
}

main().catch((error) => {
  // Avoid logging the full Axios error, which may include request headers.
  const message = error.response?.data?.message || error.message;
  console.error(message);
  process.exitCode = 1;
});

Keep your API key private and do not place it in browser-side JavaScript or a public repository.

Step 3: Run the Program

With both files in your project folder, run:

node index.js

The script performs four operations:

1. Uploads the image through Upload File Using Base64.
2. Starts an asynchronous Image-to-PDF conversion.
3. Checks the background job status until processing finishes.
4. Downloads the PDF as result.pdf.

Step 4: Review the PDF

Open result.pdf and confirm that the image appears correctly.

The sample avoids overwriting an existing file. Move or rename a previous result.pdf before running it again.

If your Base64 content already represents a PDF, it only needs decoding or uploading as a PDF; the image-conversion step is unnecessary.