Ever wanted to know what the two's complement of 1 Googol is written as a hexadecimal number? Or do you need a quick ASCII table? Bit Fiddle can help you!

- Convert artibtrary large decimal, hexadecimal or binary numbers or ASCII characters.
- Compute the 1's complement or the 2's complement.
- Alter the byte order of the input to convert between Little and Big Endian.
- View a simple ASCII table with additional information for each character.

All in a compact interface which immediately shows you all needed values just one click or keystroke away.

The conversion results are displayed in different numeral systems and with the most common integer sizes: 8, 16, 32, 64 and n bits. The n-variant uses as many bytes needed to store the unsigned representation of the entered number.

You can enter any integer number formatted in any way you like: All characters not part of an integer will automatically be omitted. Following are the digits which will be parsed:

- Decimal digits: 0123456789
- Hexadeciaml digits: 0123456789abcdef as well as ABCDEF
- Binary digits: 01 as well as the letters oiOI and L
- ASCII characters: The input encoding is UTF-8 but only the printable characters of 7-bit ASCII are visible in the output. All other characters are presented as a question mark.

The endianness conversion automatically swaps the bytes of any input and will produce output based on that converted number. Do not use this flag unless you know it is exactly what you need!

Note that converting very, very, very large numbers will take a considerable amount of time.

What's New

Version 1.3

- Refined User Interface
- Mini version.
- Stay in foreground if requested.
- Internal improvements

Ratings and Reviews

feature-rich and straight-forward


Handles 64-bit (long long) values (or bigger) and will convert between Decimal, Hexadecimal, Binary, and ASCII, exactly what I wanted in my little programmer’s toolbox (instead of figuring out how to get the LLVM debugger to show it to me :-)

Pro: Easy to use, and seems to be a solid program, no crashes, calculates flawlessly, and “does the right thing” when you start entering characters or digits in the other fields. The ASCII chart is a nice bonus too.

Con: (It is hard to offer critiques for a free app!) The user interface is a little crowded, and the separate areas (Dec/Hex/Bin…) are not visually grouped/separated clearly. Also the label text is a bit small given our larger monitors these days. Though I got used to it right away, I would probably re-arrange the window a bit and perhaps make it wider and a little shorter so it fits under my Xcode debugging window better.

Overall, very good, thank you for this great utility!

Developer Response

Thank you for your detailed review! The UI has been redesigned in one of the previous releases and includes a Mini-View now which should be small enough to fit under the debug window.

signed/unsigned problem


I cannot convert HEX to signed DEC properly. I tested all the options but no luck.
For example, how can I get 0xFF (signed 8bit integer) converted to -1?

Developer Response

Thank your for this review. Bit Fiddle will always assume the input to be unsigned. This may seem as a limitation at first but distinguishing between unsigned and signed input proved both to be confusing for the users as well as unpredictable when working with custom byte sizes. In order to properly convert 0xff to -1, you therefore need to write ff in the hex field, set the conversion to the two's complement and manually add a minus sign to the decimal number. This turned out to be easier to understand for most people.


Tobias Stamm
568.2 KB
Developer Tools
English, German
Age Rating
Rated 4+
© Manderim GmbH


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