Free Offline Image Converter - Batch Convert JPG, PNG, WEBP, ICO

Convert your images online using our batch converter for free. Standard online image conversion websites require you to upload your files to remote cloud servers, exposing your images to data leaks. Jetpap processes your images 100% locally in your browser sandbox, keeping your documents secure and private.

Introduction & Overview

Whether you are preparing images for a website header, packaging icon formats for desktop software, converting web photos for presentations, or resizing image assets for an application, converting file formats is a common task.

Our **Free Online Image Converter** gives you control over file formats and dimensions. Convert images to JPG, PNG, WEBP, BMP, or ICO, adjust lossy image quality compression parameters, apply layout resizing, rename file prefixes, and download single files or a compiled ZIP archive.

Core Features & Capabilities

Our batch image conversion workspace features multiple formatting controls:

• Batch Image Conversions: Add multiple images to the queue and convert them all simultaneously.
• Wide Format Support: Convert input files (including JPG, PNG, WEBP, GIF, BMP, TIFF, and ICO) into target formats.
• Quality Sliders: Customize compression levels (10% to 100%) for lossy formats (JPG and WEBP) to control output file sizes.
• Scale and Resize: Lock original sizes or scale images based on custom target Width or Height values.
• Custom Rename Prefix: Apply a prefix naming pattern to all output files for neat organization.
• ICO Packaging Support: Package images into Windows-compatible desktop icon formats (ICO) directly in your browser.
• ZIP Archive Download: Package converted files into a single ZIP folder for download.

How to Use: Step-by-Step Guide

Convert your images in five steps:

1. Select Files: Drag and drop images into the upload area, or click browse to choose files from your device.
2. Configure Sizing & Formats: Select your target output format (PNG, JPG, WEBP, BMP, or ICO) and set optional resizing width/height constraints.
3. Set Rename Prefix: Enter an optional prefix name in the sidebar to rename output files.
4. Convert: Click **Convert Images** to process all files locally in your browser.
5. Download Output: Click download on individual cards or click **Download All as ZIP** to save the converted files.

The Technology and Logic Behind It

Jetpap's Image Converter runs on your client device. It uses the browser's **FileReader** API to read files as local data streams.

When you initiate a conversion, JavaScript draws the images onto an HTML5 **Canvas** context. The engine resizes the canvas container according to your selected width/height constraints. For ICO outputs, a custom binary packer encapsulates PNG canvas data into a Microsoft ICO directory structure. For multiple files, **JSZip** bundles the image outputs into a ZIP folder locally.

Key Benefits of Our Tool

• 100% Client-Side Privacy: Conversions are processed locally on your device, ensuring document privacy.
• Interactive Sizing Controls: Custom resize tools allow you to change image dimensions.
• No Paywalls or Watermarks: Convert files without watermarks or registration walls.
• Offline Functionality: Once loaded, the tool can run completely offline.