About Bytewitness

Bytewitness is a free browser-based image format converter for everyday formats (JPG, PNG, WebP, GIF, BMP) plus credit-based HEIC and RAW decoding — every saved conversion gets a permanent, public Proof Page showing the real file-size and dimension change.

How conversion works

Every conversion happens entirely inside your browser using the Canvas API. When you drop a file onto Bytewitness, the following happens — all locally, with no network request:

1. The file is decoded into pixel data by the browser's native image decoder.
2. The pixel data is drawn to a hidden HTML canvas element.
3. The canvas exports the pixel data in your chosen target format via canvas.toBlob().
4. The resulting blob is offered to you as a download — no upload, no server, no copy of your file anywhere outside your machine.

This approach has two practical consequences: it's genuinely private (your files never leave your device), and it costs nothing per conversion — which is why we can offer unlimited conversions for free.

What a Proof Page is

No other image converter leaves anything behind after a conversion. Bytewitness is different: when you choose to save a conversion, it creates a permanent, public Proof Page at a clean URL (like /proof/jpg-to-png-7f3a2b) that records exactly what happened:

• The original and result file sizes
• The exact percentage change
• The image dimensions
• A plain-English explanation of what the format conversion does
• A small FAQ specific to that format pair

Proof Pages are designed to be citeable — valid structured data, real numbers, no boilerplate. You can share them, embed them as badges in blog posts, or use them as references when discussing image optimization. They're permanent and public.

Saving a Proof Page is always free and unlimited for any conversion. Converting everyday formats (JPG, PNG, WebP, GIF, BMP) is always free and unlimited. Decoding HEIC and RAW files from iPhones and cameras costs 1 credit per file — new accounts get 3 free, then $5 for 25 more.

HEIC and RAW decoding

HEIC (the default iPhone photo format) and camera RAW files require a hardware-accelerated codec decoder that browsers don't provide natively. Bytewitness loads a WASM-based decoder in a background Web Worker — the heavy decode work happens off the main thread, and your file never leaves your device. The decoded raw pixels are then re-encoded to your chosen output format using the Canvas API. The credit cost reflects the real compute involved, not an arbitrary toll.

Why "pngify.pro"?

Bytewitness is the product name. Pngify.pro is the domain — an existing domain we reused rather than registered fresh. The brand is Bytewitness; the address happens to be pngify.pro. They're simply different, the same way a company name doesn't have to match its domain.