TOML Multiline Strings and JSON Escaping

TOML provides two multiline string types that are far more readable than JSON's single-line strings with escape sequences. Understanding these is essential for configuration files containing long text, templates, or embedded code.

Basic multiline string (triple double quotes):

description = """
This is a multiline string.
It can span multiple lines.
Special characters like \n are processed."""

Converts to JSON:

{
  "description": "This is a multiline string.\nIt can span multiple lines.\nSpecial characters like \n are processed."
}

The leading newline after """ is trimmed. Subsequent line breaks become \n in JSON.

Literal multiline string (triple single quotes):

regex = '''
\d{3}-\d{2}-\d{4}
'''

winpath = '''
C:\Users\admin\Documents
'''

Converts to JSON:

{
  "regex": "\\d{3}-\\d{2}-\\d{4}\n",
  "winpath": "C:\\Users\\admin\\Documents\n"
}

In literal strings, backslashes are not escape characters. They are preserved as-is. This is ideal for regex patterns and Windows file paths.

Line ending backslash (line continuation):

long_text = """\
  The quick brown \
  fox jumps over \
  the lazy dog."""

A backslash at the end of a line trims the newline and leading whitespace on the next line, producing: "The quick brown fox jumps over the lazy dog."

Comparison of TOML string types:

Type	Syntax	Escapes	Multiline
Basic	"..."	Yes	No
Literal	'...'	No	No
Basic multiline	"""..."""	Yes	Yes
Literal multiline	'''...'''	No	Yes

Converting JSON multiline strings to TOML: When a JSON string contains \n characters, a good converter uses TOML's multiline syntax for readability. Strings with backslashes (paths, regex) benefit from literal strings to avoid double-escaping.