Regex Data Generator
Generate random strings and sample datasets that match any regex pattern — classes, ranges, alternation, groups, and quantifiers.
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What is Regex Data Generator?
A Regex Data Generator turns a regular expression into random strings that match it. Instead of hand-writing test values for a validation pattern, you paste the regex, choose a count, and get ready-made samples you can drop into unit tests, seed scripts, or QA checklists. The parser and sampler run entirely in your browser.
Key Benefits
- Instant realistic test data from existing validation patterns
- No dependencies or accounts — works offline in any modern browser
- Deterministic safety caps keep heavy patterns responsive
- Bilingual EN/TH interface with accessible markup
Common Use Cases
- •Seeding databases and spreadsheets with format-valid values
- •Unit-testing validators for emails, IDs, phone numbers, and codes
- •Generating edge-case samples for QA regression checklists
- •Producing demo data for documentation and screenshots
How to Use the Regex Data Generator
- Enter your pattern: Type a regular expression such as user-[a-z]{4,8}-\d{3}. Classes, ranges, alternation, groups, and quantifiers are all supported.
- Set flags and count: Optionally add flags like i for case-insensitive sampling, then choose how many samples to generate.
- Generate and review: Click Generate. Each row is a random string guaranteed to match your pattern. Toggle unique-only to deduplicate results.
- Copy or download: Use the per-row copy buttons, copy everything as a list, or download the samples as .txt or .json for your test fixtures.
Key Features
- Random strings matching any regex — classes, ranges, alternation, and quantifiers
- Unique-only mode for IDs, codes, and coupon values
- Presets for hex colors, UUIDs, emails, Thai phones, ISO dates, and IPv4
- Safe sampling caps prevent runaway patterns from hanging the page
- Copy per row or all at once, export .txt or .json
- 100% client-side — nothing is uploaded to any server
Frequently Asked Questions
Does every generated string really match my pattern?
Yes. The generator walks the parsed structure of your regex and builds strings character by character from its classes and literals, so every sample matches by construction. Anchors like ^ and $ are ignored because samples are standalone strings.
Which regex features are supported?
Literals, character classes with ranges and negation, alternation, groups (capturing, non-capturing, and named), the shorthand classes \d \w \s and their negations, escapes like \n and \u, and the quantifiers * + ? and {n,m}. Lookarounds, backreferences, and Unicode property escapes are rejected with a clear error because they cannot be reliably sampled.
How large can my output get?
Each quantifier is capped at 100 repeats, unbounded quantifiers add at most a few extra repeats, and total output per batch is capped at about 20,000 characters, keeping the page responsive even on heavy patterns.
Is my data sent anywhere?
No. The parser and generator run entirely in your browser. Patterns and generated samples never leave your machine, and the page works offline once loaded.