Tech tutorials, programming guides, and developer resources
OAuth 2.0 lets users grant apps access to their data without sharing passwords. Use Authorization Code flow for web apps, PKCE for SPAs and mobile, Client Credentials for server-to-server. Never store tokens in localStorage.
Zero-downtime migrations use backward-compatible steps. Add columns nullable first. Deploy code that handles both schemas. Backfill data in batches. Add constraints. Never rename or drop in one step—use expand and contract.
Feature flags are runtime toggles that control what code runs. Use them for gradual rollouts, A/B tests, kill switches, and beta access. Store in Redis or database, not config files. Kill switches save production incidents.
JavaScript runs on a single thread with an event loop. Synchronous code runs to completion. Async callbacks wait in queues. Microtasks (Promises) run before macrotasks (setTimeout). Blocking the call stack freezes everything.
PostgreSQL full-text search uses tsvector and tsquery. Index with GIN indexes. Use ts_rank for relevance, websearch_to_tsquery for user input, and pg_trgm for fuzzy matching. Handles millions of records well with no extra infrastructure.
Cache-Control headers tell browsers and CDNs how long to store responses. Use max-age for static assets, no-cache for HTML, private for user data, immutable for versioned files. ETags enable conditional requests that skip downloading unchanged content.
Webhooks are HTTP POST requests triggered by events. Verify signatures to prevent spoofing. Return 200 immediately, process async. Retry with exponential backoff. Store delivery logs. Use queues for reliability.
ACID guarantees that database operations are Atomic (all or nothing), Consistent (rules enforced), Isolated (concurrent transactions don't interfere), and Durable (committed data survives crashes). Without transactions, concurrent writes corrupt data.
Graceful shutdown drains in-flight requests before stopping. Catch SIGTERM, stop accepting new connections, wait for active requests to finish, then exit. Without it, every deploy drops requests and breaks transactions.
WebSockets enable real-time bidirectional communication. Handle reconnection with exponential backoff. Use heartbeats to detect dead connections. Scale with Redis pub/sub. Store connection state. Close connections properly.
Multi-stage builds use multiple FROM statements. Build stage has compilers and tools. Final stage has only runtime dependencies. Result: 10x smaller images, faster deploys, fewer vulnerabilities. Copy artifacts between stages.
Debouncing waits until user stops (search input). Throttling limits rate (scroll handler). Debounce = last call wins. Throttle = regular intervals. Use debounce for user input, throttle for continuous events.
Learn 10 regex patterns: email, URL, phone, credit card, password strength, whitespace, special chars, numbers, dates, and file extensions. Test on regex101.com. Use named groups. Avoid catastrophic backtracking.
Always store dates in UTC. Display in user's timezone. Never use new Date() for parsing. Avoid date math with native Date. Use date-fns or Luxon. ISO 8601 for serialization. Timezones are hard - libraries handle them.
Retry failed requests with increasing delays: 1s, 2s, 4s, 8s. Add jitter to prevent thundering herd. Stop after max retries. Exponential backoff handles transient failures and rate limits gracefully.
Cache = store expensive results in memory. Add TTL to expire old data. Use LRU to limit memory. Check cache before expensive operations. 10x-100x speed improvement for repeated data.
Use RabbitMQ for complex routing and guaranteed delivery. Use Redis for simple, fast queues. Use SQS for managed, scalable queues on AWS. All handle async tasks - choose based on complexity, scale, and infrastructure.
Load test before launch. Use k6 or Artillery to simulate traffic. Test realistic scenarios, not just homepage. Find your breaking point. Monitor CPU, memory, database connections. Fix bottlenecks before users find them.
XSS happens when user input is rendered as HTML/JavaScript. Escape all output. Use textContent not innerHTML. Sanitize HTML with DOMPurify. Enable Content Security Policy. React/Vue escape by default - don't use dangerouslySetInnerHTML.
SQL injection happens when user input goes directly into SQL queries. Never concatenate user input into SQL. Use parameterized queries, prepared statements, or ORMs. Validate input. Escape output. Test with SQLMap.
Use WebP/AVIF for 30-50% smaller files. Lazy load images below the fold. Serve responsive images with srcset. Use a CDN for fast delivery. Compress before upload. Modern formats + lazy loading = 70% faster loads.
N+1 queries happen when you fetch records in a loop - 1 query becomes 1000. Detect with query logging and APM tools. Fix with eager loading, joins, or batching. 100x performance improvement is common.
Use structured logging with levels. Log requests, errors, and key events - not sensitive data or debug spam. JSON format for aggregation. Keep performance impact under 5%. Fix log leaks before they become breaches.
Never commit secrets to Git. Use .env files locally, environment variables in production. Validate config on startup. Use dotenv for Node.js, never hardcode credentials.
Use proper HTTP status codes. Return consistent error format with code, message, and details. Log errors server-side. Never expose stack traces to clients.
URL versioning (/v1/users) is simplest and most discoverable. Header versioning is cleaner but harder to use. Start with URL versioning, only use headers if you have a strong reason.
Offset pagination is simple but slow on large datasets. Cursor pagination is fast and consistent. Use offset for small datasets, cursor for anything over 100k rows.
Sessions are simpler and more secure for traditional web apps. JWTs work better for APIs and microservices. Sessions require server state, JWTs don't. Pick based on your architecture, not hype.
Never block API responses with slow operations. Use job queues for emails, image processing, reports. Bull with Redis is simple and reliable. Process jobs in workers, not request handlers.
Caching makes apps fast. Use in-memory for single servers, Redis for distributed systems, CDN for static assets. Implement cache-aside for most use cases, write-through for consistency.
Rate limiting prevents API abuse. Token bucket is most flexible, fixed window is simplest, sliding window is most accurate. Implement in-memory for single servers, Redis for distributed systems.
Git worktree creates multiple working directories from one repository. Check out different branches side-by-side without stashing. Faster than multiple clones, cleaner than branch switching.
Indexes make queries fast by avoiding full table scans. But too many indexes slow down writes. Use EXPLAIN to identify slow queries, add indexes on WHERE/JOIN columns, and avoid indexing everything.
SQLite can handle 100k+ requests/second and terabytes of data. For read-heavy apps, single-server deployments, and edge computing, it's simpler and faster than Postgres. Know when to use it.
Every few years, a new database paradigm claims it will kill SQL and relational databases. But they always end up adding SQL interfaces and relational features. History keeps repeating itself.
SSE is simpler than WebSockets for one-way server-to-client updates. Built into browsers, works over HTTP, automatic reconnection. Use WebSockets only when you need bidirectional communication.
Microservices add operational complexity that small teams can't afford. Monoliths are faster to build, easier to debug, and simpler to deploy. Split services when you have a reason, not because it's trendy.
ORMs hide complexity that eventually bites you. Raw SQL is explicit, performant, and easier to debug. Use ORMs for CRUD, write SQL for anything complex.
Build a complete URL shortener in 30 lines of Go using only stdlib. Generates short codes, handles redirects, stores in memory - perfect learning project.
Unix philosophy teaches us that simple, focused tools that do one thing well often outlast complex alternatives. Modern examples like grep, git, and curl prove this approach still works.
UUID v7 puts timestamps at the beginning, making database indexes happy. I saw 3x better insert performance and 50% smaller indexes after migrating. Here's how and when to switch.
CORS errors are never quite the same. Here's every fix I've used in production, why each error happens, and actual code you can copy-paste for your specific situation.
Frameworks solve real problems but add complexity. Use them when they solve problems you actually have, not because they're trendy. Sometimes vanilla code is faster to write and maintain.
Binary formats like MsgPack are 20-50% smaller than JSON and much faster to parse. Use for high-performance APIs, mobile apps, and data storage.
Rust excels in systems programming, WebAssembly, and infrastructure tools, but struggles with rapid prototyping, data science, and mobile development.
WebAssembly lets you run compiled languages like C, Rust, and Go in browsers at near-native speed. Perfect for performance-critical apps, games, and computational tasks.
Master these 15 Linux command combinations to handle logs, find files, process data, and monitor systems like a pro. Copy-paste ready with explanations.
0x is the universal prefix for hexadecimal numbers — a compact, human-friendly way to represent binary values used in code, memory addresses, crypto wallets, and even CSS color codes.