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Regular expression tester

Ready

Regular expression tester. Test JavaScript regular expressions locally.

All tools are free to use. File size and processing limits may vary by tool.

How to use

Test JavaScript regular expressions locally. Maximum 100,000 input characters and 1,000 matches; long matches and capture groups are truncated. Expensive patterns are stopped after about one second.

How are files processed?

Browser tools keep files on your device. Advanced document tools upload files for temporary server processing; the tool shows this before upload. Web lookups send queries to the server and public lookup services.

Practical guide

Regular Expression Tester

A small mistake in an email pattern can block valid addresses. This tester runs JavaScript patterns directly in your browser. Type your pattern, add samples, see matches instantly. Toggle flags for case sensitivity. Everything runs locally.

Read the guide →

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JSON Formatter

Format compact or single-line JSON with readable indentation. Tidy an API response in your browser and receive a warning when JSON syntax is invalid.

How to format? Paste an API response or config file and format it; copy it into your project. See the JSON Validator for validity checks too.

JSON Validator

Paste suspicious data and run it; valid syntax earns a confirmation, broken syntax an error warning. Checking happens in this browser, data never reaches a server.

How to validate? Paste the JSON into the box and validate. Valid input returns a confirmation; fix and retry when it fails. Use it on API responses and confi

Base64 Encoder

Convert text into UTF-8 Base64 and copy the encoded result. Processing stays in your browser; Base64 is encoding, not encryption or password protection.

How to encode? Paste the text to encode and run it, then copy the result. Handy for data URIs or carrying binary content in API bodies. Use the Base64 Deco

Base64 Decoder

Decode Base64 or a data URL in your browser. View text, preview recognized images and download the decoded file without uploading the input.

How to decode? Paste Base64 or a data URL, or select a TXT/B64 file containing the code. Decode to view text, preview a recognized image or download the fi

UUID Generator

Generate a standard UUID v4 identifier. Every button press creates a new unique value. It uses the browser cryptographic number generator and sends no request to a server.

How to generate? Press the button and copy the value; use it for database keys, file names and request traces. Collision odds are negligible, yet verify prim

Unix Timestamp Converter

Convert a timestamp into a readable date and a date back into a timestamp. Second and millisecond values are supported. Everything runs in this browser, dates are never stored.

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