Developer Tools

Check whether text matches a published checksum, with a clear match or mismatch answer.

Count line, block and documentation comments, and list every TODO and FIXME.

Count code, comment and blank lines, and find the longest line in a file.

Break a Cookie or Set-Cookie header into its parts and check its security attributes.

Generate a CRC32 checksum, the 8-character value used inside ZIP and PNG files.

Build a cron expression from a plain schedule and check when it will actually run.

Explain a cron expression in English and list its next run times.

Pull every colour value out of a stylesheet and see the palette it really uses.

Delete every /* */ comment from a stylesheet.

Find selectors that are declared more than once in the same stylesheet.

List every font-family declaration in a stylesheet.

Format CSS, SCSS and Less with consistent indentation and one declaration per line.

List the media queries a stylesheet contains, so you can see its real breakpoints.

Remove comments and unnecessary whitespace from a stylesheet.

See which CSS properties a stylesheet uses and how often each one appears.

List every selector in a stylesheet, in source order.

List every custom property declared in a stylesheet with its value.

Decode an SVG data URI back into readable markup.

Convert one date into every common format at once - ISO 8601, RFC 1123, SQL, Unix and local.

Check domain names against the label and length rules of DNS.

Check a list of email addresses for structural validity.

Generate MD5, SHA-1, SHA-256, SHA-384, SHA-512, SHA3-256 and CRC32 digests at once.

Generate an HMAC signature from a message and a secret key, using SHA-256 by default.

Pull every value of one attribute out of a document - href, src, class, data-anything.

Strip every HTML comment from a document.

Indent and wrap messy HTML into readable markup, using the same engine editors run on save.

List every image with its alt text, dimensions and loading attribute.

List every link in a page with its anchor text, rel and target attributes.

Strip comments and collapse whitespace to shrink an HTML file, safely.

List the scripts a page loads, separating external files from inline code.

Check a page for the structural and SEO basics: title, description, one H1, lang, viewport, canonical and alt text.

List the stylesheets a page links to, with their media attributes.

Count how many of each element a page uses, ranked by frequency.

Pull out every occurrence of one element, with its attributes and contents.

Parse raw HTTP headers into a readable table and flag missing security headers.

Check IPv4 addresses, rejecting out-of-range octets and leading zeros.

Check IPv6 addresses, including compressed and IPv4-mapped forms.

Strip // and /* */ comments without touching comment-like text inside strings.

List everything a module exports, including named, default and re-exports.

Format JavaScript with Prettier - consistent indentation, quotes and line breaks.

List the functions declared in a file, including arrow functions assigned to a name.

List every module a file imports, including dynamic imports and require calls.

Minify JavaScript with Terser: dead code removed, names shortened, whitespace gone.

Pull every string literal out of a source file - single, double and backtick quoted.

List every const, let and var declared in a file.

List the React components used inside a JSX file.

Format React JSX with sensible attribute wrapping and indentation.

Decode a JSON Web Token and read its header and claims, with expiry checked.

Check MAC addresses in colon, hyphen or bare hexadecimal notation.

Generate the MD5 digest of any text, as 32 hexadecimal characters.

Generate the title, description, canonical, Open Graph and Twitter tags for a page, with length checks.

Find the MIME type for a file extension, offline.

Find which file extensions map to a MIME type.

Generate compact URL-safe identifiers with a configurable length and alphabet.

Generate Open Graph tags so links to your page get a proper preview card.

List every dependency with its version range and which group it belongs to.

Read a package.json at a glance: metadata, dependency counts and every script.

Generate strong random passwords with a chosen length and character set, and see their real entropy.

Turn a list of key=value lines into a correctly encoded query string.

Split a query string or full URL into its parameters, decoded and listed.

Generate random hexadecimal strings of an exact byte length.

Generate random strings from a chosen character set, using a cryptographic source.

Extract just the matches - or just one capture group - as a clean list.

Replace every regular expression match, with $1 style group references in the replacement.

Split text on a regular expression instead of a fixed separator.

Test a regular expression against your text and see every match, its position and its capture groups.

Build a robots.txt file with the paths you want kept out of crawling.

Build a correct Set-Cookie header with the security attributes chosen deliberately.

Generate the SHA-1 digest of any text, as 40 hexadecimal characters.

Generate the SHA-256 digest of any text, as 64 hexadecimal characters.

Generate the SHA-384 digest of any text, as 96 hexadecimal characters.

Generate the SHA-512 digest of any text, as 128 hexadecimal characters.

Profile a source file: size, functions, imports, exports, indentation and line endings.

Pull column names out of a CREATE TABLE statement or a SELECT list.

Strip -- line comments and /* */ block comments from a query.

Format SQL for readability, with dialect-aware keywords and consistent indentation.

Collapse a SQL query onto one line and strip its comments.

Find the tables a query reads from or writes to.

List the fill and stroke colours an SVG uses.

Count the elements in an SVG and check whether it has a viewBox.

Strip editor metadata and comments from an SVG before publishing it.

Shrink an SVG by removing editor metadata, comments and excess decimal places.

Pull the path data out of an SVG - every d attribute, one per line.

Convert an SVG into a data URI you can paste straight into CSS or an img tag.

Generate Twitter card meta tags for a rich link preview.

List the exports of a TypeScript module, values and types alike.

Format TypeScript, including type annotations, generics and decorators.

List every module a TypeScript file imports, including type-only imports.

Generate ULIDs - 26-character, lexicographically sortable, URL-safe identifiers.

Convert a Unix timestamp to a readable date, or a date to a timestamp, in seconds or milliseconds.

Break a URL into scheme, host, port, path, query and fragment, with its parameters listed.

Check a list of URLs for structural validity, and flag plain HTTP and odd hosts.

Read a user agent string: browser, version, engine, operating system and device type.

Generate cryptographically random UUIDs - version 4, or version 7 for time-sortable ids.

Check whether values are well-formed UUIDs, and read their version and timestamp.

Read a web app manifest and check it has what an installable app needs.

Generate a site.webmanifest so your site can be installed as an app.

Turn a list of URLs into a valid XML sitemap, ready to submit.