stringo

A zero-dependency string toolkit for Dart: case conversion, word splitting, slugs, truncation, masking, and whitespace normalization.

import 'package:stringo/stringo.dart';

'hello_world'.toCamelCase;        // 'helloWorld'
'parseHTTPResponse'.toSnakeCase;  // 'parse_http_response'
'Hello, World!'.slugify();        // 'hello-world'
'the lord of the rings'.toTitleCase; // 'The Lord of the Rings'
'1234567890'.mask(visibleStart: 2, visibleEnd: 2); // '12******90'

Install

dependencies:
  stringo: ^1.0.0

What it does

stringo operates on the text. Splitting, casing, trimming, slicing, masking, joining.

It does not adjudicate whether text is a valid instance of a real-world concept. There is no isValidEmail, no isValidPhoneNumber, no isValidUrl. Those rules differ per project and change over time; a package that ships one opinion about them is a package you end up fighting. Keep those in the layer that owns the rule.

API

Case conversion

Every conversion runs through toWords, so any input shape works - camelCase, PascalCase, snake_case, kebab-case, or plain spaced text.

Getter	'helloWorld' becomes
toWords	['hello', 'World']
toCamelCase	helloWorld
toPascalCase	HelloWorld
toSnakeCase	hello_world
toKebabCase	hello-world
toDotCase	hello.world
toTitleCase	Hello World
toScreamingSnakeCase	HELLO_WORLD
toScreamingKebabCase	HELLO-WORLD
toPascalSnakeCase	Hello_World
toPascalKebabCase / toTrainCase	Hello-World
toCamelSnakeCase	hello_World
toCamelKebabCase	hello-World
toFlatCase	helloworld
toScreamingCase	HELLOWORLD

toWords understands acronym boundaries: 'parseHTTPResponse'.toWords gives ['parse', 'HTTP', 'Response'].

Also: capitalizeFirstLetter, lowercaseFirstLetter, capitalizeFirstLowerRest, toTitle (title-cases while preserving - and _), and tryToLowerCase() / tryToUpperCase() for nullable strings.

toTitleCase always capitalizes the first word, then leaves the articles, conjunctions, and short prepositions in titleCaseExceptions lowercase. That list is public, so you can inspect it or build your own rule on top.

Transforms

'  Line   1 \n Line 2  '.normalizeWhitespace(); // 'Line 1 Line 2'
'Line1\n\n\nLine2'.removeEmptyLines;            // 'Line1\nLine2'
'a b\nc'.clean;                                 // 'abc'
'Hello World'.words;                            // ['Hello', 'World']
'a\r\nb'.lines;                                 // ['a', 'b']
'Hello World'.truncate(5);                      // 'Hello...'
'"quoted"'.removeSurrounding('"');              // 'quoted'
'foo=bar'.replaceAfter('=', 'baz');             // 'foo=baz'
'abc'.insert(1, 'Z');                           // 'aZbc'

Plus nullIfEmpty, nullIfBlank, orEmpty, toOneLine, removeWhiteSpaces, toCharArray(), equalsIgnoreCase, and mask().

Most of these are defined on String? and handle null without a bang operator.

Checks

Character-level predicates only: isBlank / isEmptyOrNull (and their negations), isNumeric, isAlphabet, isAlphanumeric, startsWithNumber, containsDigits, hasCapitalLetter, and hasMatch(pattern).

The underlying patterns are exported too (regexNumeric, regexAlphabet, regexAlphanumeric, regexStartsWithNumber, regexContainsDigits, regexHasCapitalLetter) so you can reuse the exact same rule elsewhere.

Known limitations

These are deliberate, documented behaviors rather than bugs:

• slugify is ASCII-only. Characters outside a-z0-9 are dropped, not transliterated, so 'Café'.slugify() gives 'caf'. Normalize accented text first if you need it preserved.
• toCharArray() splits by UTF-16 code unit, so text containing emoji is split mid-character. Use package:characters when you need grapheme clusters.
• toWords does not split on digit boundaries: 'user2Name' stays one word.
• Character checks are ASCII-only. isAlphabet is A-Z and a-z.

Related packages

Need	Package
Type conversion and JSON parsing	convert_object
Fuzzy matching, similarity, substring search	string_search_algorithms
The wider Dart utility belt (this package re-exported, plus collections, dates, intl)	dart_helper_utils

If you already depend on dart_helper_utils, you have stringo - it is re-exported there, and no import change is needed.

AI coding-assistant support

This repository ships an installable plugin with package-specific skills for Claude Code and OpenAI Codex.

# Claude Code
/plugin marketplace add omar-hanafy/stringo

# Codex CLI
codex plugin marketplace add omar-hanafy/stringo

License

BSD 3-Clause. See LICENSE.