ROT13 decoder
Apply ROT13 (and ROT47) instantly. ROT13 is its own inverse, so the same operation encodes and decodes.
Open in ctfpalROT13 is the Caesar cipher with a shift of 13. Because 13 is exactly half of 26, applying it twice returns the original - it is its own inverse, which is why it became the standard way to hide spoilers on Usenet and why it is the most common single-step obfuscation in beginner CTF challenges.
ROT47, the version that hides punctuation too
ROT13 leaves digits, braces, and underscores alone, so a ROT13'd flag still visibly looks like a flag. ROT47 rotates the entire printable ASCII range from ! to ~ by 47 positions, which scrambles the punctuation as well and makes the result look like line noise. If a blob is dense printable garbage with no recognisable structure, ROT47 is worth one click.
Worked example
Classic ROT13
Input
cvpbPGS{ebg13_vf_abg_pelcgb}Result
picoCTF{rot13_is_not_crypto}