DevScratchpad FaviconDevScratchpad
Open Tool Workspace
DEV_LEARNING_HUB // v2.0
100% Client-Side Knowledge Base
17 Practical References

Engineering Guides, Cheat Sheets & Architecture Cookbooks

Exhaustive, copy-pasteable references for everyday developer challenges. From cron schedules and JWT RFC standards to cURL conversions and modern cryptographic hashing.

CURATED LEARNING TRACKS
Structured Deep Dives
Most Popular45 mins

Application Security & Cryptography Playbook

Deep dive into RFC standards, token security, one-way password hashing, public-key infrastructure, and offline crypto.

1. OpenSSL Command Cheat Sheet: Generating Keys, CSRs & Inspecting Certificates2. How to Decode JWT Tokens3. Password Hashing Guide: Bcrypt, Argon2 & PBKDF2 Explained+3 more modules in track
Start Track
Essential35 mins

DevOps, Linux & Cloud Automation Track

Essential cheat sheets and syntax guides for cron jobs, regular expressions, network boundaries, and server maintenance.

1. Cron Expression Cheat Sheet2. Regular Expressions (Regex) Developer Cheat Sheet & Quick Recipes3. Modern HTTP Status Codes & Response Headers Guide+2 more modules in track
Start Track
Practical40 mins

API Translation & Web Data Mastery Track

Master modern API workflows: converting cURL commands to Python/Go/Fetch, translating JSON to TypeScript & Zod schemas.

1. Convert cURL to JavaScript2. How to Auto-Generate TypeScript Types & Zod Schemas from JSON3. How to Convert cURL Commands to Python requests+3 more modules in track
Start Track
INSTANT CHEAT SHEETS & ONE-LINERSCopy-Paste Ready
Click to Copy
AI & MCPTool

Claude MCP GitHub Server Spec

Model Context Protocol JSON configuration for GitHub repo tools in Claude.

{"mcpServers":{"github":{"command":"npx","args":["-y","@modelcontextprotocol/server-github"],"env":{"GITHUB_PERSONAL_ACCESS_TOKEN":"ghp_your_token"}}}}
DevOpsTool

Cron Every 15 Minutes

Runs at minute 0, 15, 30, and 45 of every hour.

*/15 * * * *
SecurityTool

Generate Ed25519 SSH Key

Modern, high-performance cryptographic SSH keypair standard.

ssh-keygen -t ed25519 -C "admin@company.com"
SecurityTool

Decode JWT in Terminal

Quickly inspect claims without leaving the terminal shell.

echo $JWT | cut -d. -f2 | base64 -d 2>/dev/null | jq .
APITool

Python requests JSON POST

Native JSON serialization with automated Content-Type header.

requests.post(url, json=payload, headers={'Authorization': f'Bearer {token}'})
SecurityTool

Inspect X.509 Certificate

Extract validity dates, SANs, and issuer details from PEM.

openssl x509 -in cert.pem -text -noout
SyntaxTool

RFC Email Regex Match

Standard email format pattern validation.

^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$
DevOpsTool

Weekly Docker Prune Crontab

Purge dangling images, containers, and volumes every Sunday at 3 AM.

0 3 * * 0 /usr/bin/docker system prune -af > /dev/null 2>&1
DataTool

Native Node.js UUID v4

Zero-dependency cryptographically secure v4 UUID generator.

crypto.randomUUID()
ALL GUIDES & REFERENCE ARCHITECTURES(17 results)
Difficulty:
DEVOPS & CLOUDCHEAT SHEET5 min read•Beginner•

Cron Expression Cheat Sheet — Complete Syntax, Examples & Schedule Guide

The ultimate reference guide to cron expression syntax. Covers 5-field & 6-field formats, special characters (*, /, -, ,), common schedules, and real-world examples.

#Cron#Linux#Kubernetes#DevOps#Crontab
DEVOPS & CLOUDCHEAT SHEET7 min read•Beginner•

Regular Expressions (Regex) Developer Cheat Sheet & Quick Recipes

Complete modern regular expression cheat sheet. Master character classes, quantifiers, lookahead, lookbehind, capturing groups, and copy-paste production recipes.

#Regex#JavaScript#Python#Syntax#Validation
API & AUTOMATIONCHEAT SHEET6 min read•Beginner•

Modern HTTP Status Codes & Response Headers Guide

Complete developer guide to HTTP status codes (2xx, 3xx, 4xx, 5xx) and essential security headers. Covers 401 vs 403, 429 rate limiting, and CORS headers.

#HTTP#API#REST#Status Codes#Security
API & AUTOMATION6 min read•Beginner•

Convert cURL to JavaScript — Fetch, Axios & Node.js Guide with Code

Learn how to convert any cURL command to native JavaScript fetch() and Axios. Covers headers, JSON bodies, bearer auth, query parameters, and error handling.

#JavaScript#TypeScript#cURL#Fetch#Axios
DATA & SERIALIZATION7 min read•Intermediate•

UUID v4, v5, and v7 Guide: Performance, Collisions & Database Indexing

Deep dive into UUID versions (v4, v5, and the new RFC 9562 v7). Learn why UUID v7 is replacing v4 for database primary keys and B-Tree indexing.

#UUID#Databases#PostgreSQL#Architecture#Performance
DATA & SERIALIZATION5 min read•Beginner•

How to Auto-Generate TypeScript Types & Zod Schemas from JSON

Learn how to instantly convert raw JSON API payloads into strict TypeScript interfaces and runtime Zod validation schemas with zero server transmission.

#TypeScript#Zod#JSON#Validation#API
SECURITY & CRYPTOGRAPHYCHEAT SHEET6 min read•Intermediate•

OpenSSL Command Cheat Sheet: Generating Keys, CSRs & Inspecting Certificates

Complete OpenSSL CLI cheat sheet for DevOps and Sysadmins. Generate private keys, create Certificate Signing Requests (CSRs), verify SSL handshakes, and convert PEM to DER.

#OpenSSL#SSL#TLS#DevOps#Certificates
API & AUTOMATION6 min read•Beginner•

How to Convert cURL Commands to Python requests — Complete Guide with Code

Step-by-step guide to converting cURL commands into clean, production-ready Python requests code. Covers GET, POST, JSON, custom headers, auth, and error handling.

#cURL#Python#API#Requests#Automation
SECURITY & CRYPTOGRAPHY6 min read•Intermediate•

How to Decode JWT Tokens — Complete Developer Guide & Security Reference

Understand the internal structure of JSON Web Tokens (JWT). Learn how to decode headers, payloads, and signatures in JavaScript, Python, and Go without external servers.

#JWT#Auth#Security#Tokens#RFC7519
SECURITY & CRYPTOGRAPHY7 min read•Intermediate•

Password Hashing Guide: Bcrypt, Argon2 & PBKDF2 Explained

A complete developer's guide to modern password hashing. Learn the differences between Bcrypt, Argon2id, and PBKDF2, and how to choose the right cost factors.

#Bcrypt#Argon2#Security#Cryptography#Hashing
SECURITY & CRYPTOGRAPHY6 min read•Intermediate•

How to Read X.509 PEM Certificates & CSRs

Learn how to parse, read, and understand X.509 SSL/TLS certificates and Certificate Signing Requests (CSR). Covers PEM structure, SANs, and Cryptographic properties.

#SSL#TLS#Certificates#X.509#DevOps
SECURITY & CRYPTOGRAPHY5 min read•Intermediate•

Generating Secure SSH Keys: Ed25519 vs RSA

Understand the differences between Ed25519, RSA, and ECDSA SSH keys. Learn why Ed25519 is the modern standard and how to generate secure keypairs.

#SSH#Ed25519#RSA#Security#DevOps
DATA & SERIALIZATION5 min read•Beginner•

Understanding Base64: Encoding, Decoding, and Binary Data

Learn how Base64 encoding works under the hood. Understand how to safely transmit binary data (images, tokens, certs) as ASCII text over the web.

#Base64#Encoding#Hex#Data#Binary
DATA & SERIALIZATION4 min read•Beginner•

JSON Formatter: Privacy Backed & 100% Client-Side Developer Tools

Learn why a privacy-backed JSON formatter is essential for developers. 100% client-side, zero server transmission formatting for sensitive API payloads.

#JSON#Client-Side#Privacy#Formatters
DATA & SERIALIZATION5 min read•Beginner•

YAML to JSON Conversion for Modern Cloud Developers

Deep dive into YAML and JSON data structures, and how developers can securely convert between them using a zero server transmission scratch pad.

#YAML#JSON#Kubernetes#DevOps#Cloud
API & AUTOMATION5 min read•Intermediate•

Translating cURL to Go, Fetch, and Python Requests

Learn how to instantly translate bash cURL commands into production-ready Go, JavaScript, and Python code using offline developer tools.

#cURL#Go#Python#JavaScript#API
API & AUTOMATION9 min read•Intermediate•

The Complete Guide to Claude Code Skills (SKILL.md), Cursor Rules (.mdc), CLAUDE.md, and MCP (2026)

An exhaustive technical guide to modern AI agent steering: Claude Code skills (SKILL.md), Cursor modular rules (.mdc), project-root CLAUDE.md, multi-agent AGENTS.md, and Model Context Protocol (claude.json) with real-time GitHub token validation.

#Claude Code#Cursor#AI Agent Skills#SKILL.md#CLAUDE.md
100% Client-Side Engine // Zero Telemetry

Looking for client-side formatters, decoders, and converters?

Explore 28 offline utilities including JSON Formatter, cURL converters, JWT decoder, UUID generator, and Bcrypt verifier.

Browse All 28 Tools