ASCII table explorer

All 128 ASCII codes in every notation, with their names from RFC 20 to Unicode 18.0.0, how to write each one in C, JSON, JavaScript, Python, Tcl, HTML and URLs, and a look-up that tells you when a character is not ASCII at all.

Documentation (Markdown)

Encoding & data

Documentation

Reads decimal, hexadecimal (0x41 or 41h), octal (0o101), seven or eight binary digits, RFC 20 column/row (4/11), U+0041, HTML references, percent-encoding, backslash escapes, caret notation, control abbreviations and names, Unicode names, or the character itself.

Try

Runs in your browser. Nothing you type leaves the page.

Code 65 0x41 · U+0041

LATIN CAPITAL LETTER A

Read as: the character itself

Numbers

Decimal: 65
Hexadecimal: 0x41
Octal: 0o101
Binary (7 bits): 1000001
In a byte (8 bits): 01000001
Column/row (RFC 20): 4/1Bits b7 b6 b5 give the column, b4 to b1 the row.

Flip a bit

Each button flips one bit and jumps to the code it lands on. b6 (value 32) separates upper and lower case; b7 (value 64) separates a control from the character it is paired with in caret notation.

Names

Unicode 18.0.0: LATIN CAPITAL LETTER A
General_Category: Lu Uppercase_Letter
RFC 20 class: Graphic character.

Relations

Other case: a, one bit away: upper and lower case differ only in b6 (value 32).

White space?

C isspace() no
JSON (RFC 8259) no
WHATWG (HTML, URLs) no
ABNF WSP (RFC 5234) no
Tcl 8.4 word separator no
Python str.isspace() no
JavaScript \s and trim() no

Which definitions count this code as white space, measured in each implementation on 2026-10-03.

How to write it

Inside a string literal of each language, or in HTML and a URL.

C	`A`	as itself
JSON	`A`	as itself
JavaScript	`A`	as itself
Python	`A`	as itself
Tcl and iRules	`A`	as itself
HTML, decimal	`A`
HTML, hexadecimal	`A`
HTML, named	none
URL	`%41`	Unreserved in RFC 3986: it never needs percent-encoding.

The table

Laid out as RFC 20 draws it: eight columns by sixteen rows. Pick a code to see it above.

Show

b7 b6 b5b4 b3 b2 b1	0000	1001	2010	3011	4100	5101	6110	7111
00000
10001
20010
30011
40100
50101
60110
70111
81000
91001
101010
111011
121100
131101
141110
151111

Text to codes

Paste text to see every character's code

White space, compared

The same ten codes, seven definitions. JSON leaves out VT and FF, WHATWG leaves out VT, Tcl ends a command at LF instead of separating words, and Python also counts the four information separators.

	9	10	11	12	13	28	29	30	31	32
C isspace()	yes	yes	yes	yes	yes	no	no	no	no	yes
JSON (RFC 8259)	yes	yes	no	no	yes	no	no	no	no	yes
WHATWG (HTML, URLs)	yes	yes	no	yes	yes	no	no	no	no	yes
ABNF WSP (RFC 5234)	yes	no	no	no	no	no	no	no	no	yes
Tcl 8.4 word separator	yes	no	yes	yes	yes	no	no	no	no	yes
Python str.isspace()	yes	yes	yes	yes	yes	yes	yes	yes	yes	yes
JavaScript \s and trim()	yes	yes	yes	yes	yes	no	no	no	no	yes

API endpointGEThttps://ronutz.com/api/v1/ascii-tableDocumented, not served. Opens the specification.