Development Tools

A list of our Development tools. Nothing you enter is sent to a server; it is all processed in your browser.

• Regex Tester

  Tests a regular expression against sample text with match highlighting, a capture group list, and a live replacement preview.

• Chmod Permission Calculator

  Converts file permissions between checkboxes, octal notation (e.g. 755), and symbolic notation (e.g. rwxr-xr-x), with setuid/setgid/sticky bit support.

• CIDR / Subnet Calculator

  Calculates the network address, broadcast address, and usable host count from CIDR notation or an IP address plus subnet mask.

• Keycode (e.code / e.key) Checker

  Shows the event.key, event.code, keyCode, location, and modifier keys of any key you press, in real time. Handy for checking values while implementing keyboard event handling.

• Screen Size & Viewport Checker

  Shows the viewport size, window size, screen resolution, device pixel ratio, and current Tailwind CSS breakpoint in real time. Handy for checking responsive designs.

• JSON Path / JSON Pointer Tester

  Tests a JSONPath or JSON Pointer (RFC 6901) query against your JSON data and lists every matched value with its absolute path. Handy for checking a query before pulling a value out of an API response.

• Base Converter (Binary/Octal/Decimal/Hex)

  Converts numbers between binary, octal, decimal, and hexadecimal in real time. Supports 0x/0b/0o prefixes and negative numbers.

• CSS Gradient Generator

  Builds linear/radial CSS gradients with a live preview from color stops, angle, and shape.

• CSS clip-path Generator

  Build clip-path shapes by dragging polygon points, or use circle, ellipse and inset, with presets like triangle, star and speech bubble.

• CSS Box-Shadow Generator

  Builds multi-layer CSS box-shadow declarations with a live preview from offset, blur, spread, color, and inset.

• CSS Border-Radius Generator

  Builds a CSS border-radius with a live preview from four independent (or linked) corner values, with px/% unit switching.

• px to rem Converter

  Converts between px and rem in real time with a customizable base font size.

• Meta Tag & OGP Generator

  Generates basic meta tags, Open Graph (OGP), and Twitter Card tags from a page title, description, URL, and image, with a social share preview.

• cURL to Fetch / Axios Converter

  Converts a curl command to JavaScript fetch or axios code. Handles headers, JSON bodies, form data, and basic auth; it only parses the command and never sends a request.

• HTTP Header Analyzer & Security Check

  Check pasted response headers for missing or weak HSTS, CSP, and cookie flags, and copy recommended nginx, Apache, or _headers config.

• CSS clamp() Calculator

  Generate a fluid typography clamp() expression from min/max font sizes and viewport widths.

• CSS Flexbox & Grid Generator

  Generate Flexbox and Grid CSS with a live preview by choosing direction, alignment, gap and columns.

• Unicode Character Inspector

  Look up code points, UTF-8/UTF-16 bytes and categories of characters, or convert U+XXXX back to text

• URL Parser & Query Editor

  Split a URL into protocol, host, path, query and hash, edit parameters and rebuild it

• User-Agent Parser

  Parse a User-Agent string into browser, OS, rendering engine and device type, and see the UA of your own browser automatically.

• CSS Text-Shadow Generator

  Builds multi-layer CSS text-shadow declarations with a live preview, including neon and outline presets.

• CSS Glassmorphism & Neumorphism Generator

  Generates CSS for frosted-glass (backdrop-filter) and neumorphic (layered box-shadow) elements with material presets and a live preview.

• CSS Animation Generator

  Builds CSS @keyframes animations from presets with cubic-bezier easing, duration, delay, iterations, and a live preview, plus prefers-reduced-motion output.

• HTTP Status Codes List & Search

  Search HTTP status codes such as 404, 301, 500, and 429 by number, name, or keyword, with meanings, causes, and fixes.

• MIME Type Lookup

  Look up the MIME type (Content-Type) for a file extension, or the extensions for a MIME type, with partial-match search

• robots.txt Generator

  Generate robots.txt with per-user-agent Allow/Disallow rules, sitemaps, and AI bot blocking

• sitemap.xml Generator (from URL list)

  Turn a URL list into sitemap.xml with bulk lastmod, changefreq and priority, invalid/duplicate URL removal, and splitting past 50,000 URLs

• .htaccess Generator (Redirects, Force HTTPS, www)

  Generate .htaccess rules for forcing HTTPS, www canonicalization, per-URL 301/302 redirects and error pages, with loop warnings

• IP Address Converter

  Convert IPv4 to decimal, hex and binary, and compress or expand IPv6 addresses. The input format is detected automatically.

• Semver Calculator

  Compare semver versions and check ranges (^ ~ >= || x, hyphen) with prerelease support, npm-compatible.

• JSON-LD Structured Data Generator

  Generate JSON-LD structured data for FAQ, Article, Product and BreadcrumbList from a form, and copy the script tag.

• UTM Builder

  Build campaign URLs with UTM parameters. Presets, bulk URLs and history. Runs in your browser.

• Htpasswd Generator (Basic Auth, bcrypt/SHA-1)

  Generate .htpasswd lines for Basic auth with bcrypt or SHA-1, for multiple users, plus Authorization headers.

• nginx Redirect Generator

  Generate nginx config for forced HTTPS, www canonical, trailing slashes and 301/302 redirects

• Port Number List & Search

  Look up TCP/UDP port numbers like 22, 80, 443, and 3306 by number, range, or service name, with their uses.

• HTML Table Generator

  Build an HTML table by choosing rows and columns. Merge cells with colspan and rowspan, add a header row, and copy the code with CSS.

• Date Format String Builder

  Builds date format strings for strftime, Java, PHP, Day.js/Moment.js and .NET from a sample, and converts between them.

• Regex Pattern Library

  Copy-ready regex patterns for Japanese postal codes, phone numbers, katakana, email, URL, IPv4, dates, and UUIDs, with match and non-match examples.

• Bitwise Calculator

  Calculate AND, OR, XOR, NOT, shifts and rotates for 8/16/32/64-bit values, with a bit-by-bit view and two's complement.

• IEEE 754 Float Viewer

  View float32/float64 sign, exponent and mantissa bits, convert from bits, and see why 0.1+0.2 is off. Handles NaN, Infinity, subnormals.

• Clipboard Inspector

  List pasted clipboard formats: MIME types, HTML source, images and files

• Snowflake ID, ObjectID & UUID Timestamp Decoder

  Decode the creation time and parts of Snowflake IDs, MongoDB ObjectIDs, UUID v1/v6/v7 and ULIDs. Batch decoding supported.

• Open Source License Generator

  Generate MIT, Apache-2.0, BSD, ISC and other license text with your name and year, plus SPDX IDs.

• Directory Tree Diagram Generator

  Turn an indented folder list into a ├── └── tree for your README. Aligned comments, depth folding, ASCII style and reverse conversion.

• CSS Filter Generator

  Build CSS filter code with live preview: blur, brightness, contrast, grayscale, hue-rotate, drop-shadow and more.

• CSS Transform Generator

  Builds CSS transform declarations with a live preview: translate, rotate, scale, skew, 3D rotation, perspective, and origin.

• CSS Specificity Calculator

  Calculate CSS selector specificity (a, b, c) line by line and compare selectors to see which rule wins.

• CSS Button & Toggle Switch Generator

  Generate CSS buttons, pure-CSS toggle switches, triangles and arrows with hover effects, a live preview and contrast check.

• CSS Pattern Background Generator

  Generate stripe, polka dot and checkerboard backgrounds as CSS gradients or SVG, preview them and copy the code.

• mailto, tel & SMS Link Generator

  Generate mailto, tel and SMS links with subject, body, CC and BCC. Get an encoded href and an HTML anchor tag.

• CSS Color Names List

  Browse all 148 CSS named colors with HEX and RGB values. Search by name or code and click to copy.

• HTML Entity List

  Look up HTML character entities by name, decimal or hex code, then copy them.

• Cron Expression Generator

  Build cron expressions visually by picking minute, hour, day, month and weekday. Supports steps, ranges, lists and Quartz output.

• ISO 8601 Duration Converter

  Converts ISO 8601 durations (PT1H30M, P1Y2M3D, P2W) to seconds, minutes, hours and days, converts seconds back, and adds a duration to a date.

• Cookie Parser (Cookie & Set-Cookie)

  Parses Cookie and Set-Cookie headers into name, value, Domain, Path, Expires, Max-Age, Secure, HttpOnly and SameSite, and flags common mistakes. Values are masked.

• umask Calculator

  Find the permissions new files and directories get from a umask, or work back to the umask you need.

• docker run to docker-compose Converter

  Converts a docker run command to a docker-compose.yml file. Handles ports, volumes, env vars, --name and --restart, and warns about options it cannot convert.

• Regex Explainer

  Break a regular expression into character classes, quantifiers, groups, lookarounds and flags, and read what each part does. Syntax errors show their position.

• CSS Unit Converter

  Convert px, rem, em, vw, vh, vmin, ch and pt between each other with your viewport and font sizes.

• Fetch / Axios to cURL Converter

  Converts JavaScript fetch or axios code to a curl command. Handles method, headers, JSON bodies, and FormData; it only parses the code and never runs it.