About

Every character rendered on a screen maps to a numeric code point defined by encoding standards. ASCII (American Standard Code for Information Interchange) assigns integers 0 - 127 to control characters, digits, Latin letters, and punctuation. Misreading a single code point turns 72 101 108 108 111 into garbage instead of "Hello." This tool parses sequences of decimal code values separated by spaces, commas, or newlines, validates each against the range 0 - 1114111 (full Unicode), and maps them to their corresponding characters via String.fromCodePoint. It flags out-of-range or non-numeric tokens individually so you can fix errors without losing the rest of the conversion.

Common use cases include decoding obfuscated log output, reversing numeric payloads in CTF challenges, and restoring data from systems that export character codes instead of raw text. The tool assumes decimal input by default. Note: control characters in the range 0 - 31 (except 9, 10, 13) produce non-printable output and are displayed as placeholder symbols.

Formulas

The conversion from a decimal ASCII code to its character representation uses the code point mapping function:

char = fromCodePoint(n)

where n is an integer satisfying 0 ≤ n ≤ 1114111 (the maximum Unicode code point, 0x10FFFF). For strict ASCII, the valid domain is 0 ≤ n ≤ 127.

When converting a full string back to ASCII codes, each character is mapped by the inverse function:

n = codePointAt(char, 0)

The delimiter auto-detection algorithm applies the following priority ruleset:

{

comma if input contains ,newline if input contains \nspace otherwise (default)

where char is any valid Unicode character, and n is its corresponding decimal code point value.

Reference Data

Dec	Hex	Char	Description
0	00	NUL	Null
7	07	BEL	Bell / Alert
9	09	TAB	Horizontal Tab
10	0A	LF	Line Feed (newline)
13	0D	CR	Carriage Return
27	1B	ESC	Escape
32	20	SP	Space
33	21	!	Exclamation Mark
34	22	"	Double Quote
35	23	#	Hash / Number Sign
39	27	'	Apostrophe
40	28	(	Left Parenthesis
42	2A	*	Asterisk
43	2B	+	Plus Sign
44	2C	,	Comma
45	2D	-	Hyphen / Minus
46	2E	.	Period / Full Stop
47	2F	/	Forward Slash
48 - 57	30-39	0-9	Digits
58	3A	:	Colon
59	3B	;	Semicolon
60	3C	<	Less Than
61	3D	=	Equals Sign
62	3E	>	Greater Than
63	3F	?	Question Mark
64	40	@	At Sign
65 - 90	41-5A	A - Z	Uppercase Latin Letters
91	5B	[	Left Square Bracket
92	5C	\	Backslash
93	5D	]	Right Square Bracket
95	5F	_	Underscore
97 - 122	61-7A	a - z	Lowercase Latin Letters
123	7B	{	Left Curly Brace
124	7C	\|	Vertical Bar / Pipe
125	7D	}	Right Curly Brace
126	7E	~	Tilde
127	7F	DEL	Delete

Frequently Asked Questions

Standard ASCII covers code points 0 - 127. This tool also supports Extended ASCII (128 - 255) and full Unicode up to 1114111 (0x10FFFF). You can toggle strict ASCII mode to reject values above 127.

The parser checks the input for commas first. If found, it splits on commas. If no commas exist, it checks for newline characters. If neither is present, it defaults to splitting on whitespace (spaces and tabs). This covers the three most common formats: "72 101 108", "72,101,108", and values on separate lines.

Code points 0 - 31 and 127 are control characters (NUL, BEL, ESC, DEL, etc.). They have no visible glyph. The tool displays a placeholder symbol (␀-series) for these so you can identify them. Only TAB (9), LF (10), and CR (13) produce recognizable whitespace.

Yes. The reverse mode (String → ASCII) handles any Unicode character including emoji, CJK ideographs, and combining marks. Note that emoji like 😀 have code points above 65535 and occupy surrogate pairs in UTF-16. The tool uses codePointAt which correctly resolves these to single code point values.

Each token is parsed individually with parseInt. If a token is not a valid integer (e.g., "abc", "12.5.3", empty string), it is flagged as an error in the output with its position index. Valid tokens in the same input are still converted normally, so one bad value does not break the entire batch.

By default, input is interpreted as decimal (base 10). You can select Hexadecimal (base 16) or Octal (base 8) input mode from the settings. Hex values like "4A 6F" and octal values like "112 157" are converted to their decimal equivalents before character mapping.