Developer tools

Format JSON, encode Base64/URL, decode JWT, generate hashes/UUIDs, test regex, and convert timestamps, colors, and number bases

• Format/validate JSON Pretty-print JSON with indentation, minify it to one line, or sort its keys. Syntax errors tell you exactly which line and column the problem is on.
• Base64 encode/decode Encodes and decodes Base64 using UTF-8 so Korean text doesn't break. Also supports the URL-safe format, converting files to Base64/data URLs, and turning Base64 back into a file.
• URL encode/decode Converts Korean URLs and query values to and from percent-encoding like %ED%95%9C. Breaks a URL down into a table of protocol, host, path, and query parameters.
• Decode JWT Decodes a JWT's header and payload into a readable format, converts exp, iat, and nbf to KST, and tells you whether it's expired. The token is never sent anywhere.
• Generate hash Calculate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes for text or a file, all at once. Also verify a downloaded file's integrity with an HMAC key or by comparing against an expected value.
• Generate UUID Generate up to 1,000 random UUID v4s, or time-ordered UUID v7s, at once. Supports uppercase, removing hyphens, and brace formatting.
• Generate password Create random passwords of 8–64 characters by choosing from uppercase, lowercase, numbers, and symbols. Also supports excluding confusing characters, generating several at once, and showing strength (entropy). Everything is generated right in your browser.
• Test regex Enter a JavaScript regex to instantly highlight matches, and see group and named-group values plus the replacement result ($1, $<name>). Includes email and phone number examples.
• Convert timestamp Converts a Unix timestamp (seconds or milliseconds) to KST, UTC, or ISO 8601, and dates to timestamps. Automatically detects seconds vs. milliseconds by digit count.
• Color conversion Convert between HEX, RGB, HSL, HSV, and CMYK color codes, and check text/background contrast against the WCAG AA/AAA standards. Also generates lighter and darker palettes.
• Base conversion Converts between binary, octal, decimal, hex, and any base from 2–36. Handles very large numbers (BigInt) precisely, with a bit view and two's complement representation for negative numbers.
• Cron expression breakdown Breaks down a cron expression like "0 9 * * 1" into plain language, such as "Every Monday at 9:00 AM," and shows the next 10 run times in KST. 6-field expressions with seconds are also supported.
• Compare text Compares two texts line by line, highlighting added/removed lines and changed characters in color. Supports ignoring whitespace/case, plus side-by-side and inline views.
• Convert HTML entities Converts < > & " to &lt; &gt; &amp; &quot; and back. Also supports named/numeric entities and \uXXXX, \u{...} Unicode escapes ↔ plain text conversion.
• Generate placeholder text Generates natural-sounding placeholder text and English Lorem ipsum for design mockups and web testing, by paragraph, sentence, or word count.