Developer Tools

Regex, text diff, case conversion, encoding, local QR codes, SemVer and line processing.

RegexDiffQRSemVer

Local tools. Inputs and files never leave your browser. Regex and diff jobs stop after 2 seconds.

Regex

Pattern (without delimiters)

Flags

Test text

Replacement ($1, $<name>, $&)

Result

Replacement preview

Regex reference

JavaScript regular expression syntax. Click an example to load it into the tester.

Examples

Character classes

Token	Meaning	Example
`.`	Any character except line breaks (with s: including)	`a.c → abc, a-c`
`\d / \D`	Digit 0–9 / not a digit	`\d+ → 42`
`\w / \W`	Word character [A-Za-z0-9_] / other	`\w+ → user_1`
`\s / \S`	Whitespace (space, tab, newline) / other	`a\sb → a b`
`[abc]`	One of the listed characters	`gr[ae]y → grey`
`[^abc]`	Any character except those listed	`[^0-9]+ → abc`
`[a-z]`	Character range	`[A-F0-9]{2} → 3E`
`\p{L}`	Any Unicode letter (requires flag u)	`\p{L}+ → Grüße`

Anchors & escaping

Token	Meaning	Example
`^`	Start of input (with m: start of line)	`^Hallo`
`$`	End of input (with m: end of line)	`\.txt$`
`\b / \B`	Word boundary / no word boundary	`\bcat\b → cat, nicht cats`
`\. \* \\`	Escape special characters to match them literally	`1\.5 → 1.5`
`\n \t`	Line break / tab	`a\nb`

Quantifiers

Token	Meaning	Example
`*`	0 or more	`ab* → a, abbb`
`+`	1 or more	`ab+ → ab, abbb`
`?`	0 or 1 (optional)	`colou?r → color`
`{n} {n,} {n,m}`	Exactly n / at least n / n to m	`\d{2,4} → 2026`
`*? +? ??`	Lazy: as few as possible	`<.+?> → <b>`

Groups & lookarounds

Token	Meaning	Example
`(abc)`	Capturing group, available as $1	`(\d+)px`
`(?<name>…)`	Named group, available as $<name>	`(?<jahr>\d{4})`
`(?:…)`	Group without capturing	`(?:ab)+ → abab`
`a\|b`	Alternative: a or b	`jpe?g\|png`
`\1`	Backreference to group 1	`(\w)\1 → ll`
`(?=…) / (?!…)`	Followed by / not followed by	`\d+(?=€)`
`(?<=…) / (?<!…)`	Preceded by / not preceded by	`(?<=\$)\d+`

Flags

Token	Meaning	Example
`g`	Global: find all matches, not just the first	`gi`
`i`	Ignore case	`abc ≙ ABC`
`m`	Multiline: ^ and $ match per line	`gm`
`s`	Dot also matches line breaks	`gs`
`u`	Unicode mode, enables \p{…}	`gu`
`y`	Sticky: match only at lastIndex	`y`

Replacement

Token	Meaning	Example
`$1 $2`	Content of group 1, 2 …	`$2.$1`
`$<name>`	Content of a named group	`$<jahr>`
`$&`	The entire match	`[$&]`
$` / $'	Text before / after the match	$`
`$$`	A literal dollar sign	`$$5`

Diff

Original

Modified

View

Result

Text

Format

Result

Encode

Text

Encoding

Direction

Result

SemVer

Version A

Version B

SemVer 2.0.0. Build metadata does not affect precedence.

Result

Lines

Split input at

Join output with

Line breaks always separate entries. Custom separators support \n and \t.

Find

Replace with

Keywords (comma-separated)

Keyword action

Find is a regular expression ($1 in replacement) Ignore case for find and keywords

Order

Trim whitespace Remove empty lines Remove duplicates

Prefix

Suffix

Order: split → find/replace → keywords → trim → remove empty → unique → sort → prefix/suffix → join.