Developer
Apps for everyday development and web work, including formatting, encoding, generation, and validation.
Color Code Converter
Convert colors between HEX, RGB, and HSL, and see them in HSV, CMYK, and OKLCH too, with a color picker, a live preview, and WCAG contrast ratios against white, black, or any text color you choose.
TOTP Generator (One-Time Passwords)
Calculate the 6-digit one-time passwords (TOTP) used for two-factor authentication from a Base32 secret, in your browser. Check a code against the ones around it, switch to SHA-256 or 8 digits, read or build otpauth:// URIs, and show a QR code for authenticator apps to scan.
XML Formatter and Minifier
Format XML that arrives on a single line into indented, readable text. Indent with 2 spaces, 4 spaces, or tabs, or minify the XML to one line. Mistakes such as an unclosed tag are reported with their line and position, and an XPath expression extracts the elements or attributes you need. Runs entirely in your browser.
Chmod Calculator (File Permissions)
Convert Linux and macOS file permissions between numbers such as 755 and symbols such as rwxr-xr-x. Switch read, write and execute on and off to build the chmod command as you go. Handles setuid, setgid and the sticky bit, and shows the permissions a umask gives new files and directories.
docker run to Docker Compose Converter (compose.yaml)
Paste docker run commands and get a compose.yaml. Reads every docker run option, including ports, environment, volumes, networks, health checks and GPUs, merges several commands into one file, rewrites $(pwd) and $ for Compose, and flags options Compose cannot express.
Hash Generator
Calculate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes of text or a file at once in hex or Base64, or HMACs with a secret key, and check them against a published checksum or webhook signature.
Basic Auth .htpasswd Generator
Make the user:hash lines of a .htpasswd file for Basic authentication with bcrypt, MD5 ($apr1$), SHA-512 ($6$), SHA-256 ($5$) or SHA-1, hashed only in your browser. Also writes the .htaccess and nginx settings and curl test commands, checks a password against an existing .htpasswd, and reads an Authorization header.
IPv4 Subnet Calculator (CIDR)
Enter an IPv4 address with a prefix length such as /24 or a subnet mask to get the network address, broadcast address, usable host range and count, and wildcard mask. It can also pick the prefix length from the number of hosts you need, and list the network split into subnets of equal size. Also shows the binary form and whether the address is private.
JSON Formatter
Format, minify, and sort the keys of JSON instantly, keeping large integers and other numbers as written if you choose. Syntax errors are shown with their line, column, and cause. Everything runs in your browser — no data is uploaded.
Markdown Table Generator
Turn cells copied from Excel or a spreadsheet into a Markdown table. Edit the cells in a grid, set each column to left, center or right alignment, and add, move, sort or swap rows and columns. The pipes line up even with Japanese and other full-width text, and you can reformat an existing Markdown table or copy it back to Excel.
Pairwise Test Case Generator
Write parameters and values to generate test cases with the pairwise (all-pairs) method: a short table in which every combination of values of any two parameters appears at least once. Supports covering three or more at a time, PICT-style input, and forbidden combinations, and exports for Excel, as CSV, or as Markdown.
Password Generator
Generate secure random passwords or word passphrases in bulk. Choose the length, character types and allowed symbols, exclude look-alikes and see a strength estimate.
Port Number Lookup
Look up what port numbers such as 22, 443, and 3306 are used for, by number, service name, or word. Lists more than 120 common ports with an explanation and covers every number in the IANA registry. Also shows which ports browsers refuse to open and reads the ports in netstat, ss, or lsof output. Runs entirely in your browser.
Regex Tester
Test a regular expression against text, highlight matches, and inspect capture groups. Named groups are listed by name, and you can preview a replacement that uses $1 or $<name>.
URL Slug Generator
Turn titles into URL slugs such as hello-world, one line at a time. Kana become Hepburn romaji and accented letters become plain letters, with a choice of separator, letter case, maximum length, English stop words, and numbers for duplicates. Can also keep Japanese in the slug and show its percent-encoded length.
UUID & ULID Generator
Generate UUID v4, time-ordered UUID v7, and ULIDs in bulk. Create up to 100 values with one click, switch UUIDs to uppercase, hyphen-less, or brace-wrapped output, and copy them. Paste a UUID or ULID to see its version and creation time and to rewrite it between ULID and UUID notation.
JSON ⇔ YAML Converter
Convert between JSON and YAML, including multi-document YAML (--- separated) to and from JSON arrays — useful for config file format conversion and data inspection.
CSV ⇔ JSON Converter
Convert between CSV or tab-separated text and JSON — turn a spreadsheet table into JSON, or a JSON array back into rows and columns. Nested JSON is expanded into columns such as address.city. Download the result as a CSV file that Excel opens without garbled text.
Calendar Event Creator (ICS File & Add-to-Google-Calendar Link)
Create an .ics file for Apple Calendar, Outlook and Google Calendar, plus add-to-calendar links for Google and Outlook. Supports all-day events, repeats (weekdays, nth weekday, count, end date), reminders and time zones.
Password Strength Checker
Check how strong a password is by finding common passwords, words, keyboard patterns, dates and more. See crack-time estimates, the weak parts and NIST guideline checks, with Japanese names, era dates and JIS keyboards covered. Nothing is sent.
CSS Unit Converter (px, rem, em, vw)
Convert between CSS px, rem, em, %, vw, vh, pt, mm and more. Set the root font size and the viewport, read a px-to-rem chart, and rewrite the px in a whole style sheet to rem at once.
HTML Escape and Unescape Tool
Replace < > & " ' with HTML character references such as <, and turn references back into characters. Non-ASCII text can become numeric references too.
JWT Decoder
Decode a JWT (JSON Web Token) header and payload, and compare its expiration time (exp) with the current time. Enter a shared secret or public key to check whether an HS256, RS256, ES256, or similar signature matches, right in the browser.
Keycode Checker (JavaScript key, code and keyCode)
Press a key to see its event.key, event.code, keyCode, modifiers and location. Get code to match the shortcut, an event history, held-key checks, and values for IME composition (keyCode 229, isComposing) and Japanese keyboard keys.
Meta Tag & OGP Generator (Title, Description, X Card)
Generate the title, description, canonical, Open Graph and X (Twitter) card tags for your page head. Preview Google results and social cards, and check text length, relative image URLs and image size.
MIME Type Lookup
Look up the MIME type (Content-Type) for an extension such as .jpg or .json, or the extensions for a MIME type. Lists more than 90 types common on the web, with their other spellings and whether IANA has registered them. Choose a file to tell its format from the mark in its content and check it against the extension. Runs entirely in your browser.
Punycode Converter (IDN ⇔ xn--)
Convert internationalized domain names to their xn-- Punycode form and back, line by line. In URLs and email addresses only the domain is converted, with case and width mapping, invalid characters and mixed-script look-alikes reported.
Random Number Generator
Generate random whole numbers between a minimum and a maximum. Draw 1 to 1,000 at once, with or without repeats, leave out chosen numbers, and sort or keep the drawn order, with the sum shown.
URL Encoder / Decoder
Percent-encode strings for URLs or decode encoded strings back, with options for a whole URL that keeps : / ? & = and for the form format that writes spaces as +. Runs entirely in your browser.
User-Agent Parser & Browser Info Checker
See this browser's User-Agent and environment (browser, OS, screen size and more) and copy it all at once. Paste User-Agent strings or access log lines to break them down by browser, OS, device and search or AI bot, with totals and notes on frozen version numbers.
Base64 Encoder / Decoder
Encode text or files such as images to Base64, and decode Base64 back to text or a file. Handles data URLs and the URL-safe form (Base64URL). UTF-8 aware and runs entirely in your browser.
Cron Expression Parser
Turn a cron expression into a plain-English description and list its next run times, or build one by choosing a schedule such as every day or every week. A mistake is reported with the field that caused it.
HTTP Status Code Lookup
Look up what HTTP status codes such as 404 and 503 mean, by number, name, or a word from the description. Lists every code in the IANA registry from 1xx to 5xx with a short explanation and the RFC that defines it. Runs entirely in your browser.
Unicode Escape Converter
Turn text into Unicode escapes such as \u3042, and turn \uXXXX, \u{...}, and \UXXXXXXXX back into characters. Covers the forms used by JSON, Java, JavaScript, and Python, and can escape only invisible characters such as zero width spaces and look-alike spaces to find them.
URL Parser and Query String Viewer
Split a URL into its scheme, host, port, path, query string, and fragment, and list its query parameters decoded. Also gives you the URL without tracking parameters such as utm_source, and lets you change, add, or remove parameters to rebuild the URL. Runs entirely in your browser.
