Regex Tester

Write a pattern, paste sample text, and see every match with its position and capture groups. Matches are highlighted in place so you can confirm the boundaries at a glance. Patterns use the JavaScript regular-expression engine.

Pattern

idle

Do not type the surrounding slashes — the leading / and trailing /flags are added for you. Named groups such as (?<name>…) are supported.

Flags

g global — find all matches i ignore case m multiline — ^/$ per line s dot matches newline u unicode mode

Examples

Test string

0 characters · capped at 100,000 characters as a safeguard against slow patterns

Matches

0 matches

Highlighted text

Match details

How to use

Type the pattern without delimiters, then choose the flags you need.
Every match is numbered with its start index and length.
Capture groups appear in a table beneath each match, including named groups.
The highlighted panel shows matches in context; zero-width matches are shown with a caret marker.
Try one of the ready-made Examples to see the expected output shape.

Syntax quick reference

`\d` `\w` `\s`	digit, word char, whitespace
`.`	any char except newline
`*` `+` `?`	0+, 1+, 0 or 1 (greedy)
`{2,5}`	between 2 and 5 times
`(…)`	capturing group
`(?:…)`	non-capturing group
`(?<n>…)`	named group
`(?=…)` `(?!…)`	lookahead / negative lookahead
`^` `$`	start / end of input or line
`[a-z]`	character class or range

Performance guard

Test strings are truncated at 100,000 characters and the match list stops at 5,000 results. Both limits exist to keep the page responsive if a pattern backtracks heavily; the tool reports when either limit is hit.