Demystifying RFC standards, cryptographic ciphers, and algorithmic formulas. Every guide is backed by interactive, zero-server developer utilities executing 100% locally in browser memory.
// 100% In-Browser Cryptographic Hashing
const payload = "rfc-conformance-vector";
const hash = await window.crypto.subtle.digest(
"SHA-256", new TextEncoder().encode(payload)
);
Learn how EXIF, XMP, and IPTC metadata are stored inside JPEG and PNG files, exactly which fields expose your location and devices, which platforms strip them and which do not, and how to remove them without recompressing the image.
Calculate GST correctly under the 0%, 5%, 18%, and 40% structure effective 22 September 2025. Learn forward and reverse GST formulas, intra-state versus inter-state splits, rounding rules, and invoice-level arithmetic.
Learn how HMAC keyed hashing works under RFC 2104, why H(key || message) is broken, and how to verify Stripe, GitHub, and Shopify webhook signatures correctly with raw bodies and constant-time comparison.
Understand how authenticator apps generate 6-digit 2FA codes. Learn the RFC 6238 time-step formula, HOTP dynamic truncation, Base32 secret encoding, otpauth:// URI parameters, and clock drift windows.
Audit and deploy the response headers that actually stop attacks. Covers strict CSP with nonces, HSTS preload requirements, frame-ancestors, Permissions-Policy, COOP/COEP, and the headers you should delete.
Understand how tokenizers split text, why token counts differ per provider, and how to compute API spend correctly — including cache reads, batch discounts, and the multi-turn history multiplier that wrecks naive estimates.
Understand the PDF object model — xref tables, page trees, and incremental updates — then learn exactly what merging and splitting preserve or destroy: bookmarks, form fields, links, tags, and hidden data.
Learn what to strip before a prompt leaves your machine, how to detect API keys and personal data with pattern plus entropy checks, why reversible placeholders beat blunt masking, and where regex-based DLP fails.
Understand how JavaScript’s backtracking regex engine works, what makes a pattern degrade to exponential time, and the concrete rewrites that make catastrophic backtracking impossible.
Compare RSA and elliptic curve keypairs by security strength, performance, and encoding. Learn PKCS#8 and SPKI PEM structure, why SSH needs a different format, and where post-quantum migration stands.
Derive the SIP future-value formula from first principles, understand why a monthly rate is not the annual rate divided by twelve in real markets, and learn how step-up contributions, XIRR, and equity fund taxation change the outcome.
Learn which characters are reserved, why encodeURI and encodeURIComponent behave differently, when a space becomes a plus sign, and how double-encoding silently breaks production URLs.
Decode X.509 v3 certificates field by field. Learn why Common Name no longer matters, how chain path validation works, what AIA and OCSP stapling do, and how the CA/Browser Forum lifetime reductions change renewal automation.
Deep dive into AES-GCM and AES-CBC symmetric cryptography. Learn Galois/Counter Mode authenticated encryption, 96-bit IV generation, and client-side Web Crypto security.
Deep dive into RFC 4648 Base64 encoding and RFC 2397 Data URIs. Learn 6-bit chunking mechanics, padding rules, image/font inlining tradeoffs, and UTF-8 safety.
Master cron expression syntax across standard 5-field UNIX and 6-field extended formats. Learn field orders, special operators, production recipes, and timezone pitfalls.
Master payroll time arithmetic: convert hours and minutes to decimal hours, calculate daily vs weekly overtime (1.5x/2.0x), deduct unpaid meal breaks, and avoid rounding disputes.
Demystify CIDR notation and IPv4 subnetting. Learn the binary bitmask formula for network addresses, broadcast IPs, and usable host ranges with a complete cheat sheet.
Understand the reducing-balance loan EMI formula. Learn how amortization schedules work, analyze interest vs principal allocation, and calculate prepayment savings.
Master global time zone conversions and Daylight Saving Time (DST) shifts. Learn how the IANA database calculates time offsets without scheduling blunders.
Learn how to compress JPEG, PNG, and WebP images to exact target file sizes (100KB, 200KB, 500KB) directly in your browser using client-side HTML5 Canvas and binary search quantization.
Step-by-step tutorial on formatting, validating, and debugging JSON payloads locally in your browser. Complete guide to syntax errors, RFC 8259 rules, and zero-server security.
Understand cryptographic hashing algorithms (SHA-256, MD5, SHA-512). Learn why MD5 is broken, how SHA-256 secures data integrity, and hash strings locally.
Understand JSON Web Tokens (RFC 7519). Learn how to decode Base64Url headers, inspect standard claims, and prevent token vulnerabilities safely in your browser.
Comprehensive guide comparing random UUID v4 with time-ordered UUID v7. Learn how RFC 9562 solves B-Tree database index fragmentation and generate cryptographically secure IDs.
Skip slow command-line installs, insecure pastebin uploaders, and privacy-invasive cloud portals. Format JSON, generate RFC 9562 UUIDs, inspect JWT tokens, test regular expressions, and convert files—100% locally in your browser’s private memory sandbox.
https://toolbox.vishnudigital.com