ASCII Control Code Table
Reference the ASCII control codes — the non-printing characters below space.
The characters you can't see
The first thirty-two ASCII codes are control characters, not printable symbols — things like tab, newline, carriage return, and older terminal controls. This is a reference to what each one is and does, so you can identify a control character in data, understand an escape sequence, or work out what an invisible byte in a file represents.
Browse the control codes and their meanings.
Where control codes still bite
Most control characters are historical, but a few cause real, modern headaches. The difference between a line feed and a carriage return is behind the classic Windows-versus-Unix line-ending problem that garbles files moved between systems. The null character terminates strings in some languages and can break data. A stray tab hides among spaces and misaligns everything. Knowing what these invisible codes are is often the key to a text bug that makes no sense until you realise a control character is lurking in the data.
Frequently asked questions
What are ASCII control characters?
The first 32 codes — tab, newline, carriage return and older terminal controls — that are non-printing rather than visible symbols.
Why do line endings cause problems?
Windows and Unix use different control characters to end lines, which garbles files moved between the two systems.
Is anything uploaded?
No. It is a reference that runs in your browser.