The card catalog for IT.

Data & size

Mbps → MB/s

Convert network speed between bits and bytes per second.

Data & size

GB ↔ MB converter

Convert between decimal and binary storage units.

Data & size

Image size calculator

Estimate uncompressed file size from resolution and color depth.

Number systems

Binary / decimal converter

Convert instantly between binary, decimal, octal and hex.

Number systems

Hexadecimal converter

Convert hex to text, decimal, binary and back.

Number systems

Unix timestamp converter

Convert Unix time to a human-readable date, and back.

Network & security

IP subnet calculator

Get network, broadcast, usable range and host count from a CIDR.

Network & security

VLSM subnet planner

Carve one block into several right-sized subnets.

Network & security

Domain WHOIS lookup

Look up registrar, dates, name servers and status for a domain.

Network & security

Password generator

Generate strong random passwords with custom rules.

Network & security

Hash generator

MD5, SHA-1, SHA-256 and SHA-512 of any text.

Network & security

RSA / EC key pair generator

Generate a standalone public/private key pair.

Network & security

HMAC generator

Generate a keyed-hash message authentication code.

Network & security

AES encrypt / decrypt

Symmetric encryption of text with a passphrase, in your browser.

Network & security

Password strength analyzer

Estimate how long a password would take to crack.

Network & security

TOTP code generator

Generate time-based one-time codes for testing 2FA.

Network & security

PGP key viewer

Inspect a public key: fingerprint, key ID, algorithm, creation date.

Encoding & text

URL encoder / decoder

Percent-encode or decode a string or full URL.

Encoding & text

Base64 encoder / decoder

Encode or decode Base64 text.

Encoding & text

JSON formatter

Pretty-print, minify and validate JSON.

Encoding & text

UUID generator

Generate v4 UUIDs, one at a time or in bulk.

Encoding & text

Regex tester

Test a regular expression against sample text live.

Design

QR code generator

Turn a URL or text into a downloadable QR code.

Design

Color converter

Convert between HEX, RGB and HSL.

Design

Color contrast checker

Check WCAG AA/AAA contrast ratio between two colors.

Design

Image color palette extractor

Pull the dominant colors out of an image.

Design

Image metadata (EXIF) viewer

View camera, GPS and other EXIF data embedded in a photo.

Text tools

Text statistics

Word, character and sentence counts, plus reading time.

Text tools

Duplicate line remover

Remove duplicate lines from a list, preserving order.

Text tools

List sorter

Sort, reverse or shuffle a list of lines.

Text tools

Find & replace

Bulk find and replace across a block of text, with regex support.

Text tools

Markdown table generator

Turn pasted tabular data into an aligned Markdown table.

Text tools

ASCII art banner

Turn text into a block-letter ASCII banner.

Text tools

Word frequency counter

Count how often each word appears in a text.

Time & everyday conversions

World clock

See the current time in multiple cities at once.

Time & everyday conversions

Timezone converter

Convert a time between any two timezones.

Time & everyday conversions

Date difference calculator

Calculate days, weeks or months between two dates.

Time & everyday conversions

Roman numeral converter

Convert between numbers and Roman numerals.

Time & everyday conversions

Text ↔ binary converter

Convert text to binary/octal/hex and back.

Time & everyday conversions

Text ↔ Unicode converter

Look up Unicode code points for characters, and back.

Time & everyday conversions

Text → NATO alphabet

Spell out text using the NATO phonetic alphabet.

Time & everyday conversions

Math evaluator

Evaluate a math expression, with common functions.

Time & everyday conversions

Percentage calculator

Percentage of a number, percent change, and more.

Time & everyday conversions

Temperature converter

Convert between Celsius, Fahrenheit and Kelvin.

Time & everyday conversions

Image resize / compress

Resize an image and adjust its compression quality.

Reference

Chmod calculator

Convert between octal and rwx permission notation.

Reference

Common ports reference

Searchable list of well-known and registered network ports.

Reference

HTTP status code reference

Every HTTP status code with a plain-English explanation.

Reference

MIME types reference

Look up the MIME type for a file extension, or vice versa.

Reference

Linux commands reference

Searchable reference for common Linux commands with examples.

Reference

Git cheatsheet

Searchable reference for common Git commands.

Reference

Regex cheatsheet

Common regular expression patterns and syntax reference.

Hosting & web server tools

.htaccess generator

Build redirects and rewrite rules for Apache.

Hosting & web server tools

htpasswd generator

Hash passwords for Apache Basic Auth (bcrypt, apr1, SHA1).

Hosting & web server tools

robots.txt generator

Build allow/disallow rules and a sitemap reference.

Hosting & web server tools

Meta tag generator

SEO meta tags and Open Graph / Twitter card tags.

Hosting & web server tools

Favicon generator

Generate a full favicon set from one image.

Hosting & web server tools

PHP environment info

This server's PHP version, extensions and limits.

Hosting & web server tools

robots.txt tester

Check whether a path is allowed for a given crawler.

Hosting & web server tools

CSP builder

Build a Content-Security-Policy header.

Hosting & web server tools

Cache-Control builder

Build a Cache-Control header for HTTP responses.

DNS & network diagnostics

DNS lookup

A, AAAA, MX, TXT, NS, CNAME and CAA records for a domain.

DNS & network diagnostics

Email deliverability checker

Look up and validate a domain's SPF, DKIM and DMARC records.

DNS & network diagnostics

HTTP header inspector

See response headers, status code and the redirect chain.

DNS & network diagnostics

Security headers checker

Grade a site's CSP, HSTS and other security headers.

DNS & network diagnostics

Port checker

Check whether a host:port is open.

DNS & network diagnostics

What's my IP

Shows the IP address this server sees for you.

DNS & network diagnostics

IPv4 address converter

Convert an IPv4 address between dotted-decimal, hex, binary and integer.

DNS & network diagnostics

CIDR range expander

Expand a CIDR block into its full IP range, or the reverse.

DNS & network diagnostics

MAC address lookup

Look up the hardware vendor for a MAC address.

DNS & network diagnostics

MAC address generator

Generate random MAC addresses, valid or locally-administered.

DNS & network diagnostics

IP geolocation lookup

Look up the approximate location and ISP for an IP address.

DNS & network diagnostics

CORS checker

Test whether a URL sends proper cross-origin headers for a given origin.

DNS & network diagnostics

Website speed checker

Measure connect time, time to first byte, and total load time.

DNS & network diagnostics

Email header analyzer

Parse raw email headers and trace the delivery hops.

Developer utilities

JWT decoder

Inspect a JSON Web Token's header and payload claims.

Developer utilities

Cron expression parser

Explain a cron expression in plain English and show next run times.

Developer utilities

Diff checker

Compare two blocks of text, line by line.

Developer utilities

Case converter

Convert text between camelCase, snake_case, kebab-case and more.

Developer utilities

Lorem ipsum generator

Generate placeholder paragraphs, sentences or words.

Developer utilities

Slug generator

Turn text into a URL-friendly slug.

Developer utilities

Docker run → Compose

Convert a docker run command into a docker-compose.yml.

Developer utilities

SQL formatter

Pretty-print a SQL query for readability.

Developer utilities

Email normalizer

Strip dots and +tags to find an address's canonical form.

Developer utilities

URL parser

Break a URL down into its components.

Developer utilities

Basic Auth header generator

Build an Authorization: Basic header from a username and password.

Developer utilities

HTML entity encoder / decoder

Convert special characters to and from HTML entities.

Developer utilities

User agent parser

Break down a User-Agent string into browser, engine and OS.

Developer utilities

DB connection string tool

Build or parse MySQL, PostgreSQL, MongoDB and Redis connection strings.

Developer utilities

.env file validator

Check .env syntax and flag likely-exposed secrets.

File & format converters

Image converter

Convert between PNG, JPG, WEBP, GIF, BMP and ICO.

File & format converters

SVG converter

Rasterize SVG to PNG/JPG, or wrap a raster image as SVG.

File & format converters

Document converter

Convert between DOCX, TXT, HTML — and more, where the server allows it.

File & format converters

Markdown converter

Convert between Markdown, HTML and plain text.

File & format converters

PDF tools

Text or images to PDF, and PDF back to plain text.

File & format converters

File to Base64

Encode any file to Base64, or decode Base64 back to a file.

File & format converters

CSV ↔ JSON converter

Convert tabular CSV data to JSON, and back.

File & format converters

YAML ↔ JSON ↔ TOML

Convert between these three config/data formats.

File & format converters

XML ↔ JSON converter

Convert between XML and JSON.

File & format converters

JSON diff

Compare two JSON documents structurally, not just line by line.

File & format converters

IBAN validator

Validate and parse an International Bank Account Number.

File & format converters

Phone number formatter

Validate and format international phone numbers.

File & format converters

Ebook converter

Convert between EPUB, MOBI, AZW3, FB2, PDF, DOCX, TXT and more.

File & format converters

PDF merge

Combine multiple PDF files into one.

File & format converters

PDF split

Split a PDF into individual pages or a page range.

SSL & certificate tools

SSL checker

Inspect a live host's TLS certificate — issuer, SANs, expiry.

SSL & certificate tools

SSL & CSR decoder

Paste a PEM certificate or CSR to decode every field.

SSL & certificate tools

CSR generator

Generate a private key and certificate signing request.

SSL & certificate tools

SSL converter

Convert certificates between PEM and PKCS#12 (.pfx).

SSL & certificate tools

OCSP checker

Check a certificate's live revocation status.

SSL & certificate tools

Key matcher

Confirm a private key matches a certificate or CSR.

SSL & certificate tools

CA matcher

Verify a certificate was signed by a given CA certificate.

SSL & certificate tools

CT log tool

Look up a domain's issued certificates in public CT logs.

SSL & certificate tools

OpenSSL trace

A verbose, server-side summary of a TLS handshake.

SSL & certificate tools

RSA key converter

Convert keys between PEM and DER, inspect key details.

SSL & certificate tools

Bulk SSL checker

Check certificate expiry for a list of hosts at once.

SSL & certificate tools

Alt DCV checker

Check HTTP, DNS TXT or CNAME domain-validation records.

SSL & certificate tools

TLS protocol & cipher checker

Check which TLS versions a server supports.

SSL & certificate tools

SPKI pin generator

Generate an HPKP/certificate-pinning hash from a certificate or key.