Convert .gitignore rules into regex
Parse a gitignore file, see each rule's equivalent regex, and test paths against the combined ignore behaviour. Runs locally.
node_modules/(?:^|/)node_modules(?:/|$)dist/(?:^|/)dist(?:/|$)*.log(?:^|/)[^/]*\.log(?:/|$)!important.log(?:^|/)important\.log(?:/|$)/build^build(?:/|$)src/**/*.tmp^src/(?:.*/)?[^/]*\.tmp(?:/|$)node_modules/foo/index.jsby node_modules/dist/main.jsby dist/app.logby *.logimportant.logby !important.logbuild/outby /buildsrc/a/b/test.tmpby src/**/*.tmpREADME.mdHow to convert .gitignore to regex
Parse .gitignore rules, see each rule's equivalent regex, and test paths against the combined ignore behaviour.
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Paste rules
Comments and blank lines are skipped. Negations (!) and dir-only (/) are preserved.
Patterns compile through the JavaScript RegExp constructor, so syntax errors surface immediately and engine quirks like Unicode property escapes (\p{L}) work when the u flag is on.
patternECMAScriptliteralliveinput · literalrules · regexnode_modules/ *.logloaded · ECMAScriptPCRE · ready - 02
Read regex
Each rule expands into its equivalent regex (with anchors and dir-only suffixes).
Each flag character mirrors the ECMAScript literal: g enables iteration, i folds case, m anchors per line, s lets . match newlines, u unlocks proper Unicode, y is sticky, and d emits indices.
flagsoptionsg · i · mliveconfig · optionsregex · flags^node_modules(?:/|$)flags applied · liveECMA · live - 03
Test paths
Drop paths to see whether each gets IGNORED or tracked, and by which rule.
Watch for catastrophic backtracking on nested quantifiers — a common ReDoS source. The tool caps match counts to keep the page responsive on pathological patterns.
matchgroupshighlightReDoS-saferun · outputverify · matchesIGNORED node_modules/foo/index.jsmatches · livegroups · live - 04
Copy or export
Grab the output as JSON, CSV, or plain text — ready for your editor or pipeline.
Copy writes via navigator.clipboard.writeText; downloads use a Blob and object URL, so nothing transits the network and the output is byte-identical to what you see on screen.
copyexportclipboardblobexport · exportedready · savedCopiedready to shipsuccess
Regex patterns that don't melt down
Use named groups
(?<year>\d{4}) reads better than $1 and survives reordering. Supported in ECMAScript 2018+.
Anchor strictly
Use ^/$ with the m flag when matching whole lines. Without anchors, partial matches sneak through.
Avoid catastrophic backtracking
Nested quantifiers like (a+)+ can explode. Run patterns through ReDoS Detector first.
Escape every literal
Backslash any meta character you want literally: \.\$\^\*\+\?\(\)\[\]\{\}\|\\.
Test edge cases
Empty string, single character, unicode, the maximum length you expect — write fixtures for each.
Patterns aren’t parsers
Don’t parse HTML, JSON, or balanced parens with regex. Use a proper parser when the grammar is recursive.
When to inspect .gitignore
Audit, teach, and port ignore rules confidently.
Audit your gitignore
Confirm node_modules is actually ignored. Compiles through the JavaScript RegExp constructor — engine quirks (Unicode property escapes, sticky matching, named groups) work when their flags are on. Error messages cite the exact position of any syntax issue.
ReDoS-safeBuild dotfiles
Sanity-check before committing a new ignore set. Pairs with the ReDoS detector to catch catastrophic backtracking before you deploy. A pattern that handles 1k-character input fine can become a denial-of-service vector on attacker-controlled 1M-character input.
ECMA-compliantPort to .dockerignore
Compare semantics across ignore files. Output exports as JavaScript, Python re, Java util.regex, .NET System.Text.RegularExpressions, PCRE, and POSIX — language quirks are highlighted on conversion so you don't ship a JS-only pattern to a Go service.
spec-gradeTeach gitignore
Show how rules compose with negation. Capture groups (named or numbered) round-trip cleanly into replacement strings, JSON output, or CSV extraction without re-typing. Backreferences ($1, ${name}) preserve semantics across languages.
cross-engineCatch overrides
See which rule wins for a path. Test against edge cases — empty input, single character, max length, multibyte boundaries — to catch off-by-one and zero-length match bugs before they reach production.
test-readyProgrammatic use
Lift the regex into a script that mimics gitignore. All matching runs client-side so secret patterns never leave the browser. Useful when the pattern itself is sensitive (PII regexes, internal data formats, security filters).
production-readyFrequently asked questions
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Tell us what you need. We ship the top requests every two weeks.