Developer tutorials and explainers on encoding, cryptography, data formats, regex, and web development.
Base64 encoding converts binary data into ASCII text using a set of 64 printable characters. It is used to safely transmit binary content over text-based protocols like HTTP and email.
JWT security failures are consistently among the top API vulnerabilities. Use RS256 or ES256 algorithms, reject the none algorithm, set short expiry times, and always verify signatures server-side.
UUID v4 generates a fully random 128-bit identifier, while UUID v7 prefixes a millisecond Unix timestamp making IDs sortable by creation time. Use UUID v7 for database primary keys.
Regular expressions match text patterns using character classes, quantifiers, anchors, and groups. This reference covers the 20 most important regex constructs with practical examples.
MD5 and SHA-1 are cryptographically broken. Use SHA-256 for general data integrity, SHA-512 for high-security applications, bcrypt or Argon2 for password hashing.
URL encoding converts characters that are not allowed in URLs into percent-encoded equivalents. Use encodeURIComponent to encode individual query parameter values.
A cron expression has five fields — minute, hour, day-of-month, month, day-of-week — that define when a job runs. This guide covers all cron syntax with 20 practical examples.
JSON is the right choice for APIs and programmatic configuration. YAML is better for human-authored configuration where readability and comments matter. YAML is a superset of JSON.
HEX is the most compact notation for fixed colors in CSS. RGB is best for controlling individual channels. HSL is better for programmatic color manipulation like rotating hue.
WCAG 2.1 requires a minimum 4.5:1 contrast ratio for normal text and 3:1 for large text at Level AA. Contrast ratio is calculated from relative luminance values, not color difference.
Binary code represents text as sequences of 0s and 1s grouped into 8-bit bytes. A character encoding maps each character to one or more byte values — ASCII uses 7 bits per character, UTF-8 uses one to four bytes.
Convert SVG to PNG when the destination cannot render vectors — social preview images, most email clients, and app store assets all require raster input. Keep the SVG everywhere a browser renders it, because one file covers every size.
A CSR holds a subject distinguished name, a public key, and a self-signature proving you hold the matching private key. A CA adds an issuer, serial, validity window and its own signature to produce an X.509 certificate.