Evergreen tools and references for developers and security engineers.
Defient.io is a focused, no-fluff library of browser-based utilities and structured technical references. Every page is engineered to be fast, accurate, and useful years from now — not a blog, not a SaaS, not a sales funnel.
Browser-based utilities
All processing runs locally in your browser. Nothing is uploaded, logged, or stored.
JSON Formatter
Validate, prettify, and minify JSON with size feedback and detailed error reporting.
JWT Decoder
Inspect a JSON Web Token's header, payload, and signature. Detects expiry and algorithm.
Base64 Encode/Decode
Convert text and UTF-8 content to and from Base64. RFC 4648 compliant in the browser.
Password Generator
Strong, cryptographically-random passwords with entropy reporting and exclusion rules.
Regex Tester
Test JavaScript regular expressions against sample text. Capture groups, flags, live matches.
UUID Generator
Generate v4 UUIDs in bulk. Configurable casing and hyphenation. Crypto-backed randomness.
SHA Hash Generator
Compute SHA-1, SHA-256, SHA-384, and SHA-512 digests using the Web Crypto API.
IP Subnet Calculator
CIDR breakdown — network, broadcast, host range, mask, wildcard, and address counts.
Eight focused knowledge areas
Each category is a curated hub: tools, references, and authoritative external sources kept in one place.
Tools
Encoders, generators, parsers, hashers, calculators. All run in your browser.
// 02Security
OWASP Top 10, authentication, cryptography fundamentals, common attack patterns.
// 03Networking
DNS, subnetting, IPv4/IPv6, common ports, TLS, the protocols that move packets.
// 04Web Development
HTTP methods and headers, status codes, CORS, REST and GraphQL fundamentals.
// 05Protocols
HTTP/1.1 through HTTP/3, WebSockets, WebRTC, gRPC, SMTP, SSH, FTP/SFTP.
// 06Encoding
UTF-8, ASCII, Unicode, MIME, Base64 — how computers represent text and bytes.
// 07Performance
Core Web Vitals, lazy loading, modern image formats, compression and caching.
// 08References
Cheat sheets and quick-lookup tables for Linux, Git, Bash, Vim, regex, and cron.
Structured technical documentation
Compact, accurate, and dense — designed for engineers who want answers, not narrative.
HTTP Status Codes
Complete list of HTTP response codes — 1xx through 5xx — with semantics and use cases.
DNS Record Types
A, AAAA, CNAME, MX, TXT, NS, SOA, SRV, CAA — what each record does and when to use it.
TLS Handshake
How TLS 1.2 and 1.3 negotiate encryption, authentication, and forward secrecy.
HTTP Headers Reference
Request and response headers grouped by purpose — caching, CORS, security, content.
Common Network Ports
Well-known and registered TCP/UDP ports for the services engineers actually meet.
Authentication Methods
Basic, Bearer, API keys, OAuth 2.0, OIDC, mTLS — when and why to choose each.
REST vs GraphQL
Architectural trade-offs, request shape, caching, tooling, and real-world fit.
Linux Command Cheat Sheet
Files, processes, networking, permissions, packages — the daily-use commands.
MIME Types List
Searchable list of common Internet media types with extensions and descriptions.
Protocols, end to end
From the application layer down — focused write-ups linking to the canonical RFCs.
HTTP/2
Binary framing, multiplexing, header compression, server push.
HTTP/3 and QUIC
UDP-based transport, 0-RTT, connection migration, head-of-line elimination.
WebSockets
Full-duplex framing over a single TCP connection. The RFC 6455 lifecycle.
WebRTC
Peer-to-peer media and data channels — ICE, STUN, TURN, SDP.
gRPC
HTTP/2-based RPC with Protocol Buffers. Unary, server, client, and bidi streaming.
SMTP
How mail moves between servers — the verbs, the codes, the relays.
FTP & SFTP
Classic FTP, FTPS, and SFTP. Why SFTP isn't FTP and what to use instead.
SSH
The Secure Shell protocol — transport, authentication, channel multiplexing.
Cheat sheets and quick-lookup tables
Dense, scannable references for the commands and patterns you reach for daily.
Git Commands Cheat Sheet
Branching, merging, rebasing, undoing — the verbs you'll use this week.
Bash Cheat Sheet
Variables, conditionals, loops, pipes, redirection, and shell expansion.
Regex Cheat Sheet
Anchors, classes, quantifiers, lookaround, and flags in one screenful.
Vim Cheat Sheet
Modes, motions, operators, registers, search, and substitution.
Cron Syntax Reference
The five-field expression, special strings, and the gotchas that bite production.
ASCII Table
Decimal, hex, octal, and character columns for all 128 ASCII code points.
About Defient.io. This is a fully static reference site — every page is a hand-built HTML document with no analytics, no cookies, and no account system. Tools run entirely in your browser using the Web Crypto API and standard DOM APIs. Sources include MDN Web Docs, the RFC Editor, OWASP, Cloudflare Learning Center, W3C, and IETF.