Regex Generator

A regex generator creates a regular expression from a practical preset, sample goal, or plain-language description. The generated pattern is a starting point that should be tested against valid, invalid, boundary, and international inputs before it is used in an application.

Choose a preset such as email, URL, UUID, IPv4, ISO date, phone number, slug, or hex color, or describe the kind of text you want to match. ToolsSonic fills an editable JavaScript-compatible pattern, applies the selected flags, and tests it against the sample text in the same browser page.

Yes, the page recognizes common plain-language goals such as email addresses, URLs, UUIDs, IPv4 addresses, dates, phone numbers, usernames, postal codes, JWT-shaped tokens, quoted strings, and semantic versions. For an uncommon or ambiguous description, use the generated pattern as a draft and refine it manually.

Yes. The default output is designed for JavaScript RegExp syntax and shows a /pattern/flags literal. The page also offers raw pattern and new RegExp() constructor formats. Other engines such as PCRE, Python, .NET, Java, and RE2 have different features, escaping rules, and lookbehind or Unicode support.

The practical presets include email addresses, HTTP or HTTPS URLs, IPv4 addresses, UUIDs, ISO dates, North American phone numbers, CSS hex colors, URL slugs, usernames, US ZIP codes, integers, whitespace runs, HTML-like tags, JWT-shaped tokens, quoted strings, and semantic versions.

Yes. The generated expression is an editable field. Change a character class, quantifier, anchor, group, or literal and the match preview, positions, capture groups, warnings, and token explanation update locally as you type.

g finds multiple matches instead of stopping at the first; i ignores letter case; m makes ^ and $ work across lines; s lets a dot match line terminators; and u enables Unicode-aware matching behavior. The global flag is enabled by default but can be turned off for first-match testing.

Yes. The test panel runs the current JavaScript pattern against sample text and highlights matches. It also reports match indexes and lengths, capture-group values, named groups when present, pattern length, test length, and warnings.

The page catches the JavaScript RegExp error and displays an Invalid status with the browser error message. It does not silently replace the expression or report false matches. Correct the pattern or flags and the live inspection resumes.

Yes. Numbered capture groups are displayed for each match, and named capture groups are shown with their names when the JavaScript engine supports them. Unmatched optional groups are labeled as not participating so empty values are not confused with missing groups.

Yes. The email preset matches common email-shaped strings with a local part, an at sign, a domain, and a dotted alphabetic suffix. It is not a complete implementation of every valid email grammar, so use application-level email verification and a confirmation workflow when correctness matters.

Yes. The IPv4 preset checks four dot-separated octets and restricts each octet to the 0–255 range. It does not determine whether an address is routable, private, assigned, reachable, or appropriate for a particular network policy.

Yes. The ISO date preset matches the YYYY-MM-DD shape and reasonable month and day ranges. A regular expression does not fully validate calendar semantics such as leap years or the number of days in February; parse the date after the shape check.

Yes. Copy regex copies the selected output format, Copy report copies the pattern, goal, flags, match count, and test text, and Download .txt saves a local text report. The actions run in the browser and do not require an account or remote conversion job.

The tool is designed as a free browser utility with no account required. Pattern construction, JavaScript matching, token explanations, statistics, copy, and download run locally without uploading test text or storing persistent history. Clipboard permissions and access to a shared device remain outside the page.

A regex can enforce a superficial password shape, but it cannot measure password strength or replace secure authentication design. Do not put secrets into shared devices or untrusted pages, and use a password-hashing function and server-side security controls rather than relying on a client-side regex.

Regex can locate simple tags or text fragments, and the HTML-tag preset is intended for inspection only. It is not a substitute for an HTML or JSON parser because nested structure, escaping, comments, entities, and malformed documents require syntax-aware processing.

Regular expression flavors differ. JavaScript, PCRE, Python, .NET, Java, and RE2 support different escapes, flags, lookarounds, backreferences, Unicode behavior, and performance rules. Treat the JavaScript output as a language-specific starting point and test it in the target runtime.

No. The page applies a match-count safety cap for local testing, but it does not prove that a pattern is safe for every input or engine. Avoid nested ambiguous quantifiers, test adversarial inputs, and use engine-specific safeguards when processing untrusted text.

Test valid examples, invalid examples, empty strings, boundary lengths, punctuation, line breaks, Unicode characters, repeated matches, optional groups, and unexpectedly long input. Also confirm the target engine, flags, anchors, escaping, performance, and whether a parser would be safer for the data format.

Start here when you do not have a pattern yet — describe the goal or pick a preset and get a working expression. Then open it in the Regex Tester to debug matches, groups, and replacements against your real sample text.