ASCII Table

What is this for?

ASCII (American Standard Code for Information Interchange) is the 128-character encoding standard that maps characters 0–127 to integers. It's the foundation of every modern text encoding — UTF-8, Latin-1, Windows-1252 all extend it — so understanding ASCII values becomes essential when debugging binary data, writing parsers, or investigating text corruption.

When to use it

• Reading a hex dump and translating byte sequences back to readable characters or control codes.
• Writing a parser and needing exact boundary values: 0x20 (space) marks the start of printable ASCII, 0x7E (tilde) marks the end.
• Debugging corrupted or malformed data — a CSV import failed because a field contained 0x09 (Tab) or 0x1F (Unit Separator), breaking your delimiter logic.
• Converting characters to HTML entities: you know A renders as A, but need to verify the decimal value quickly.
• Resolving platform differences: confirming whether your regex should match \r (0x0D, Carriage Return) or \n (0x0A, Line Feed) or both.
• Inspecting control characters in logs or network traffic — identifying whether that invisible character is BEL (0x07), ESC (0x1B), or something else entirely.

How it works

• Enter a search term (decimal, hex, character, or description) into the filter box and the table updates instantly.
• View all 128 ASCII codes at once with decimal, hexadecimal, octal, and binary representations side by side.
• Click or copy any row to see HTML entity codes for characters that need escaping in markup.
• Control characters (0x00–0x1F and 0x7F) show human-readable descriptions so you know what BEL, ESC, or NUL actually do.

Common gotchas

• ASCII is strictly 7-bit. Byte values 128–255 are not ASCII — they belong to whatever 8-bit encoding the document declares (Latin-1, CP-1252, Shift-JIS) or form the lead bytes of a UTF-8 multi-byte sequence. Don't assume a byte outside 0–127 is ASCII.
• Newlines are platform-dependent. Unix and macOS use LF alone (0x0A); legacy Mac Classic used CR only (0x0D); Windows uses CRLF (both). Code that assumes one format will miscount lines or fail to parse files from other platforms.
• Control characters hide silently. Copy-pasting from a terminal, PDF, or rich-text editor can introduce invisible characters like 0x1F (Unit Separator), 0x07 (BEL), or zero-width Unicode that aren't ASCII at all. If text looks identical but fails equality checks, always dump the bytes.
• HTML entities are context-dependent. In UTF-8 documents, A and a literal A are equivalent. Only escape the five characters that hold syntactic meaning in HTML: &, <, >, ", and '.
• NUL (0x00) terminates C strings. Many C APIs and legacy systems treat NUL as an end-of-string marker. Embedding NUL in a buffer without explicit length handling causes silent truncation.

Reference notes

• Codes 0x00–0x1F and 0x7F are control characters — most are invisible and often have no printable representation.
• Codes 0x20–0x7E (space through tilde) are the printable ASCII range.
• The high bit (0x80) is not part of standard ASCII and marks the boundary where extended encodings diverge.