OpenedFile
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About OpenedFile

Our Mission

OpenedFile was created with a simple mission: make file conversion private, free, and instant. We believe you shouldn't have to upload sensitive documents, personal photos, or confidential email attachments to a remote server just to convert them into a usable format.

Every day, millions of people encounter files they can't open — WebP images downloaded from the web, HEIC photos from iPhones, or mysterious winmail.dat attachments from Outlook. Most online converters require you to upload these files to their servers, where they may be stored, analyzed, or shared without your knowledge. We built OpenedFile to provide a better alternative.

Why Client-Side Processing?

Privacy is not just a feature — it's the foundation of everything we do. All of our tools run entirely within your web browser. When you convert a file on OpenedFile, the processing happens on your device using technologies like JavaScript, WebAssembly, and the HTML5 Canvas API. Your files are never uploaded to any server. Not ours, not anyone else's.

This approach has several important benefits:

  • Complete Privacy: Your files never leave your device. There's no risk of data breaches, unauthorized access, or third-party sharing because your data never travels over the internet.
  • Speed: Since there's no upload or download step, conversions are nearly instant. The speed depends only on your device's processing power, not your internet connection.
  • Works Offline: Once the page has loaded, most of our tools work without an internet connection. Your files can be converted even on an airplane or in areas with poor connectivity.
  • No File Size Limits: Server-based converters often impose strict file size limits. Our tools are limited only by your device's available memory, allowing you to process much larger files.
  • No Registration: You don't need to create an account, provide an email address, or sign up for anything. Just open the tool and start converting.

Our Tools

OpenedFile currently offers the following conversion tools:

WebP to JPG/PNG Converter

Convert WebP images to universally compatible JPG or PNG format. Supports batch conversion with adjustable quality settings. Uses the HTML5 Canvas API for instant, client-side processing.

HEIC to JPG/PNG Converter

Convert iPhone and iPad HEIC/HEIF photos to JPG or PNG. Powered by WebAssembly-based decoding for fast, high-quality conversion. Perfect for opening iOS photos on Windows or sharing with non-Apple users.

Winmail.dat Viewer & Extractor

Open and extract contents from winmail.dat email attachments created by Microsoft Outlook. View email subject, sender, body text, and download embedded file attachments. Uses a custom-built TNEF parser with full support for Japanese and international filenames.

How It Works

Our tools leverage modern web technologies to perform all file processing directly in your browser:

  • HTML5 Canvas API: Used for image format conversion (WebP to JPG/PNG), providing native browser support for encoding and decoding image formats.
  • WebAssembly (Wasm): Used for HEIC/HEIF decoding, enabling near-native performance for complex image processing tasks that would be too slow in pure JavaScript.
  • Custom TNEF Parser: Our winmail.dat tool uses a purpose-built TypeScript parser that decodes the binary TNEF format, extracts MAPI properties, and correctly handles multi-byte character encodings like Shift_JIS and UTF-16LE.
  • DOMPurify: HTML email content from winmail.dat files is sanitized using DOMPurify before being displayed in a sandboxed iframe, ensuring security even with potentially malicious email content.

What's Next

We are actively developing new tools and improving existing ones. Planned additions include:

  • PDF tools (merge, split, compress)
  • SVG to PNG/JPG converter
  • Image compression and optimization tools
  • Additional email format support

Have a suggestion for a tool you'd like to see? We'd love to hear from you. Get in touch.

Open and Transparent

OpenedFile is built on the principle that file conversion should be accessible to everyone, regardless of technical skill, operating system, or budget. We are committed to keeping our core tools free and maintaining the highest standards of user privacy. Thank you for choosing OpenedFile.