Extending n8n running locally python scripts using Flask

Hi everyone!

I want to share what I've done to extend the functionality of n8n by running Python code using a Flask server, so don't need to pay for Cloudconver and similar APIs. I’m running n8n locally in Docker and have added a new image conversion function that converts images from PNG to Webp format. This is done through a Python script that I’ve integrated into my setup. I’ve also created an n8n node that calls this function, converts the image, and returns the converted image back to my workflow.

This ins json for import n8n node, just copy and paste inside n8n workflow

{
  "name": "Tests",
  "nodes": [
    {
      "parameters": {
        "method": "POST",
        "url": "http://host.docker.internal:5000/convert",
        "sendBody": true,
        "contentType": "multipart-form-data",
        "bodyParameters": {
          "parameters": [
            {
              "parameterType": "formBinaryData",
              "name": "file",
              "inputDataFieldName": "data"
            },
            {
              "name": "original_filename",
              "value": "={{ $binary.data.fileName || 'image.png' }}"
            }
          ]
        },
        "options": {}
      },
      "name": "Flask Converter",
      "type": "n8n-nodes-base.httpRequest",
      "typeVersion": 4.1,
      "position": [
        -820,
        20
      ],
      "id": "483881d3-6574-4eec-91e9-4715e185657c",
      "alwaysOutputData": false,
      "notes": "After importing, you must manually set this node to send the file using the instructions provided."
    }
  ],
  "pinData": {},
  "connections": {},
  "active": false,
  "settings": {
    "executionOrder": "v1"
  },
  "versionId": "6ace63f3-e1f3-48ad-a929-c0ca4ba0887c",
  "meta": {
    "instanceId": "44c216c02c6f01f2fef8eb2ad71aa75c1545e5519733c0a1e6fb1f2fc1b2fa36"
  },
  "id": "mKN69KiJtr7j68C3",
  "tags": []
}

this is python script

import sys
import os
from PIL import Image
from flask import Flask, request, send_file, jsonify
import io


def convert_png_to_webp(input_path, output_path=None, quality=80):
    if not input_path.lower().endswith('.png'):
        raise ValueError('Input file must be a PNG image suka.')

    if output_path is None:
        output_path = os.path.splitext(input_path)[0] + '.webp'

    with Image.open(input_path) as img:
        img.save(output_path, 'WEBP', quality=quality)
    print(f"Converted '{input_path}' to '{output_path}' (quality={quality})")


def main():
    if len(sys.argv) < 2:
        print("Usage: python png_to_webp_converter.py <input_png> [output_webp] [quality]")
        sys.exit(1)

    input_path = sys.argv[1]
    output_path = sys.argv[2] if len(sys.argv) > 2 else None
    quality = int(sys.argv[3]) if len(sys.argv) > 3 else 80

    try:
        convert_png_to_webp(input_path, output_path, quality)
    except Exception as e:
        print(f"Error: {e}")
        sys.exit(1)


app = Flask(__name__)

@app.route('/convert', methods=['POST'])
def convert():
    if 'file' not in request.files:
        return jsonify({'error': 'No file part'}), 400

    file = request.files['file']
    if not file or not getattr(file, 'filename', None):
        return jsonify({'error': 'No selected file'}), 400

    original_filename = request.form.get('original_filename', 'image.png')

    base_name = os.path.splitext(original_filename)[0]
    webp_filename = f"{base_name}.webp"

    try:
        img = Image.open(file.stream)

        if img.format != 'PNG':
            return jsonify({'error': f'Only PNG files are supported. Received: {img.format}'}), 400

        file.stream.seek(0)

        output = io.BytesIO()
        img.save(output, format='WEBP', quality=80)
        output.seek(0)

        return send_file(output, mimetype='image/webp', as_attachment=True, download_name=webp_filename)

    except Exception as e:
        return jsonify({'error': f'Error processing image: {str(e)}'}), 500

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=5000, debug=True)