turtledragonfly

There are a lot of interesting tools in this area.

Here's a previous comment of mine with a list of various such things: https://news.ycombinator.com/item?id=34990984

There was some good discussion on that previous post from others, as well.

lars_francke
You might be interested in ImHex https://github.com/WerWolv/ImHex Seems similar to Hexfiend but cross platform and very powerful. I have never used Hexfiend though, so can't really compare. Just going by the GitHub readme.