Regex Tester

Test JavaScript regular expressions.

How the regex tester works

Patterns run with the browser's JavaScript RegExp engine. Matches are highlighted, and numbered and named capture groups are listed for each match.

Beware of catastrophic backtracking: nested quantifiers like (a+)+ can freeze a page on certain inputs. DevCipher caps the number of matches shown at 1,000.

Processed locally in your browser — your input is never uploaded.

What is Regex Tester?

Test JavaScript regular expressions. Patterns run with the browser's JavaScript RegExp engine. Matches are highlighted, and numbered and named capture groups are listed for each match.

Is Regex Tester free to use?

Yes. Regex Tester on DevCipher is completely free, with no sign-up, no limits and no ads.

Is my data safe when I use Regex Tester?

Yes. Everything runs locally in your browser. Your input is never uploaded to a server, and sensitive values such as keys and tokens are never saved.

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Base64 Decoder — Decode Base64 back to text
Base64URL Encoder — URL-safe Base64 without padding
Base64URL Decoder — Decode URL-safe Base64
URL Encoder — Percent-encode text for URLs
URL Decoder — Decode percent-encoded text
Hex Encoder — Convert text to hexadecimal bytes
Hex Decoder — Convert hexadecimal bytes to text
Binary Encoder — Convert text to 8-bit binary
Binary Decoder — Convert 8-bit binary to text
Unicode Encoder — Escape characters as \uXXXX
Unicode Decoder — Turn \uXXXX escapes into text
HTML Entity Encoder — Escape &, <, >, quotes for HTML
HTML Entity Decoder — Turn entities back into characters
Image to Base64 — Convert an image to a Base64 data URI
Base64 to Image — Decode Base64 to an image and download it
AES Encrypt / Decrypt — AES-128/192/256 encryption and decryption
RSA & PEM Tools — Generate keys, encrypt, decrypt, sign, verify
Hash Generator — MD5, SHA-1/2/3, SHAKE and BLAKE2
HMAC Generator — Keyed hashes: HMAC-SHA256 and more
String ⇄ JSON — Convert escaped strings to JSON and back
JSON Formatter — Format, validate and minify JSON
JSON Comparator — Find differences between two JSON documents
JSON Tree Viewer — Explore JSON as an expandable tree
JSON to Code — Generate types for TypeScript, Java, Go, Python, C#
JWT Decoder — Decode and inspect JSON Web Tokens
JWT Generator — Create signed HS, RS and ES tokens
URL Parser — Break a URL into its components
Query String Parser — Parse and build query strings
UUID Generator — Generate UUID v4 and v7
Password Generator — Strong random passwords
Random String Generator — Secure random strings and tokens
Timestamp Converter — Unix timestamps ⇄ human dates
Number Base Converter — Binary, octal, decimal, hex and more
Color Converter — HEX, RGB and HSL with contrast check
Regex Tester — Test JavaScript regular expressions
CSV ⇄ JSON — Convert between CSV and JSON
YAML Formatter — Format, validate and convert YAML
XML Formatter — Pretty print, minify and validate XML
SQL Formatter — Format SQL for many dialects