Conversion
Format Converter
Convert images between JPEG, PNG, WebP, and more.
Your files stay on your device - processed locally via WebAssembly, never uploaded
Drop your files here
JPEG, PNG, WebP, AVIF, HEIC, TIFF, GIF, SVG, BMP, PDF - or paste (Ctrl+V)
Output Format
Web Optimized
Lossless
Special
Quality: 80%
What is the best free image converter without upload?
OptiPix Image Converter converts between JPEG, PNG, WebP, and AVIF using the jSquash WebAssembly codecs, entirely on your device. Unlike CloudConvert or Convertio, there are no per-day conversion limits, no 100 MB cap, and no server ever sees your images.
Embed this tool on your website
Copy this code to add the Format Converter to your site for free. It runs entirely in your visitors' browsers - no API key, no usage limits.
<iframe src="https://optipix.art/embed/format-converter" width="100%" height="600" style="border:1px solid #e4e4e7;border-radius:8px;" title="Format Converter by OptiPix" loading="lazy"></iframe> <p style="font-size:12px">Free tool by <a href="https://optipix.art/format-converter">OptiPix Format Converter</a></p>
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About Format Converter
Last updated: May 2026
OptiPix Format Converter lets you quickly convert images between all major formats including JPEG, PNG, WebP, BMP, and HEIC (iPhone photos). The converter uses the browser's native Canvas API for standard formats and the heic2any library for HEIC conversion, ensuring fast processing without any server uploads. This is especially useful for converting iPhone HEIC photos to JPEG or PNG for broader compatibility, converting PNG screenshots to JPEG to reduce file size, or converting images to WebP for optimal web performance. The tool preserves image dimensions and quality during conversion - you get a pixel-perfect copy in the new format. Batch conversion is supported, letting you convert multiple files at once. All processing happens locally in your browser, so your photos remain private. The converter handles transparency properly when converting between formats that support it (PNG, WebP) and those that do not (JPEG).
How It Works
The converter loads your image onto an HTML Canvas element and re-encodes it in the target format using the browser's built-in encoding capabilities. For HEIC files, the heic2any library first decodes the HEIC data before Canvas re-encoding.
Use Cases
- •Convert iPhone HEIC photos to JPEG for universal sharing
- •Convert PNG screenshots to JPEG for smaller file sizes
- •Convert images to WebP for optimized web performance
- •Convert BMP files to modern formats
- •Prepare images in specific formats required by platforms
You Might Also Like
If you find Format Converter useful, check out these related tools: Image to SVG, Image Compressor, and Image to PDF. All tools run entirely in your browser with no uploads or signups required.
Explore more: Browse all tools · Step-by-step guides · Tips & tutorials · Compare tools
OptiPix Format Converter vs CloudConvert vs Convertio vs iLoveIMG
| Feature | OptiPix | CloudConvert | Convertio | iLoveIMG |
|---|---|---|---|---|
| Files uploaded to a server | Never | Yes | Yes | Yes |
| HEIC support | Yes, decoded locally | Yes | Yes | Yes |
| AVIF + WebP output | Yes | Yes | Yes | WebP only |
| Free limits | Unlimited | 25/day | Size-capped free | Batch limits free |
| Quality control on output | Yes | Yes | Yes | Limited |
Competitor details reflect publicly listed free-tier features and may change.
Codec-level conversion details
Each output format uses a real reference encoder compiled to WebAssembly via the jSquash project: MozJPEG for JPEG, OxiPNG for PNG, libwebp for WebP, and libaom/libavif for AVIF. These are the same codecs inside Chrome and professional build pipelines, not a generic canvas re-encode.
iPhone HEIC photos are decoded entirely in-browser, fixing the most common conversion need - HEIC to JPEG for sharing with Windows and Android users - without handing your camera roll to a cloud service. EXIF orientation is honored so portrait shots don't arrive sideways.
Transparency is handled per-format: PNG and WebP preserve the alpha channel; converting transparent images to JPEG composites them onto a background color you choose, since JPEG has no alpha support. AVIF preserves alpha and typically lands 40-60% smaller than the equivalent PNG.
Frequently Asked Questions
Can I convert iPhone HEIC photos?
Does conversion affect image quality?
Can I convert multiple images at once?
What happens to transparency when converting to JPEG?
Is WebP smaller than JPEG?
How do I convert HEIC to JPG for free?
Should I convert my images to WebP or AVIF?
Does converting PNG to JPG lose transparency?
How do I convert a PNG to JPG for free?
Should I use WebP or PNG?
What is AVIF and should I convert my images to it?
Can I convert image formats without uploading my photos?
Does converting JPG to PNG improve quality?
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