Esoteric Programming Languages (Esolangs)

What is an Esolang?

An Esoteric Programming Language (Esolang) is a programming language designed to experiment with weird concepts, be extremely difficult to program in, or serve as a joke/puzzle.

In CTFs, organisers often hide flags inside esolang source code files.

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1. Brainfuck

Brainfuck operates on an array of memory cells (tape) initialized to zero, driven by an instruction pointer. It uses only 8 commands:

Command	Action
>	Increment memory pointer (move right).
<	Decrement memory pointer (move left).
+	Increment byte value at memory pointer.
-	Decrement byte value at memory pointer.
.	Output character byte at memory pointer.
,	Input byte and store at memory pointer.
[	If byte at memory pointer is zero, jump forward to matching ].
]	If byte at memory pointer is non-zero, jump back to matching [.

Sample Brainfuck “Hello World”

+++++++[>++++++++++++<-]>++.

Use CyberChef’s Brainfuck operation or dcode.fr/brainfuck-language to run and decode instantly.

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2. Whitespace

In Whitespace, non-whitespace characters are ignored completely. Code consists entirely of Spaces, Tabs, and Line Feeds (Newlines).

• In code editors, highlight all text (Ctrl+A) to reveal hidden pattern layouts of spaces and tabs.

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3. Piet

Piet is a visual esolang where programs are bitmap images that look like abstract art (resembling Piet Mondrian paintings).

The interpreter tracks a color pointer moving through contiguous blocks of color.

• Tool: Use npiet or online visual Piet interpreters (www.bertnase.de/npiet/) to execute Piet .png image files.

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4. Befunge

Befunge is a 2D grid-based language where instructions are arranged on a playfield, and the execution arrow (>, <, ^, v) changes direction dynamically.

>25*"!dlroW ,olleH":v
                v:<|_@