Hooray, it's Hex Fiend 2, a nearly complete rewrite of Hex Fiend that incorporates even better techniques for working with big files. Hex Fiend is my fast and clever hex editor for Mac OS X.

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This app is about exploring the implementation of standard desktop UI features in the realm of files too large to fully read into main memory. Is it possible to do copy and paste, find and replace, undo and redo, on a document that may top a hundred gigabytes, and make it feel natural? Where do we run into trouble?

More on that later. For now, here's what's better about Hex Fiend 2:

• It's embeddable. The most requested feature was "I want a hex view in my app." Now it's really easy: Hex Fiend 2 is built as a relatively slim shell on top of a bundle-embeddable .framework. There's a real API, sample code, and everything. See the Developer section of the Hex Fiend page.
• It's faster. All around. Text rendering is speedier, and the backing data representation more efficient. It needs less I/O too.

  The save algorithm is especially improved. For example, inserting one byte at the beginning of a 340 MB file and hitting Save would take 52 seconds and 340 additional MB of temporary disk space with Hex Fiend. In Hex Fiend 2 it's reduced to 22 seconds and requires no temporary disk space.

• Better UI. It supports discontiguous selection. Scroll-wheel scrolling no longer feels weird. You can group the bytes into blocks (credit to Blake), and you can hide and show different views (thanks to bbum). The big dorky line number view now shrinks to fit. The data inspector panel is inline. It has Safari-style inline find and replace and "pop out" selection highlighting.
• Long operations support progress reporting, cancellation, and don't block the UI. For example, find and replace now has a progress bar and a cancel button, and you can keep using your document (or others) while it works.
  
  
• Longstanding bugfixes. Backwards searching is now optimized. Certain coalesced undo bugs have been addressed. There's some basic cross-file dependency tracking.