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Every EasySpawn article, newest first — deploying AI-built apps, Claude Code, databases, security, and the infrastructure underneath.
422 posts · page 2 of 18
Does Your App Need Terms of Service? What to Include
Terms of service aren't usually required by law, but they're how you limit liability, set rules, handle payments and refunds, and shut down abusive accounts. When you need them, what sections matter, how to get users to agree properly, and the mistakes to avoid.
TanStack Query vs useEffect for Data Fetching in React
Fetching in useEffect looks simple until you need loading states, errors, caching, race conditions, refetching and mutations. What TanStack Query handles for you, side-by-side code, mutations with invalidation, and when server components or plain useEffect are still the right choice.
Stripe Subscriptions Explained: Products, Prices, Webhooks and Access
How Stripe Billing models subscriptions — customers, products, prices, subscriptions and invoices — which webhooks to handle, what each subscription status means for access, trials, upgrades and proration, failed payments and dunning, and the Customer Portal.
Stripe Payment Links vs Checkout vs Elements: Which Do You Need?
Stripe offers three ways to take payments, from zero code to fully custom. Payment Links need no code, Checkout is a hosted page you create from your server, and Elements embeds payment fields in your own UI. What each can do, and how to pick.
Streaming LLM Responses to the Browser: SSE, Fetch Streams, and Gotchas
Streaming makes AI features feel fast: words appear as they're generated instead of after a ten-second wait. How to stream from the Claude API on your server, forward it to the browser, read it in React, and fix the proxies and timeouts that buffer or cut off streams.
How to Secure a New VPS: The First 30 Minutes
A fresh server is scanned within minutes of going online. The essential hardening steps for a new Ubuntu VPS: updates, a non-root user, SSH keys only, firewall, automatic security patches, fail2ban, safe service binding, backups and monitoring — in order, with commands.
React vs Vue vs Svelte: Which Frontend Framework Should You Learn?
Three popular ways to build interactive web interfaces. How they differ in syntax, size, learning curve, ecosystem and jobs — and why, if you build with AI tools, the answer is usually React even when another option is nicer.
React useState Explained: How State Actually Works
useState gives a component memory that survives re-renders and updates the screen when it changes. How it works, why the value doesn't change immediately after you set it, updating objects and arrays without mutating them, and the functional update form.
React useEffect Explained: When to Use It (and When Not To)
useEffect runs code after React renders, to sync your component with something outside React — a timer, a subscription, a browser API. How the dependency array works, cleanup functions, why effects run twice in development, and the many cases where you don't need an effect at all.
"Each Child in a List Should Have a Unique Key Prop": What It Means
React's key warning appears when you render a list without telling React which item is which. Why keys matter, why array index is a bad key for lists that change, what to use instead, and how to fix the warning in fragments and nested maps.
React "Too Many Re-renders" and "Maximum Update Depth Exceeded": Fixes
Both errors mean a component keeps updating state, which re-renders it, which updates state again — forever. The four patterns that cause it (calling a handler instead of passing it, setState during render, effects without dependencies, objects in dependency arrays) and their fixes.
React State Management: useState vs Context vs Zustand vs Redux
Most React apps need less state management than they think. Sort your state into server, URL, form, local and global, then pick the lightest tool for each: useState, the URL, React Context, Zustand, Redux Toolkit or Jotai. Trade-offs, examples and common mistakes.
React Server Components Explained: "use client", "use server", and What Runs Where
Server Components render on the server and send no JavaScript; Client Components hydrate in the browser for interactivity. How the boundary works, what 'use client' and 'use server' actually mean, passing data across, common errors, and how to keep secrets and bundles where they belong.
Prompt Caching Explained: Cut LLM Costs and Latency on Repeated Prompts
If every request repeats the same long system prompt, documents or tool definitions, prompt caching lets the provider reuse that work for a fraction of the price and time. How it works, structuring prompts for cache hits, Claude's cache_control, OpenAI's automatic caching, and verifying it works.
Postgres Roles and Permissions: CREATE USER, GRANT, and Least Privilege
Most apps connect to Postgres as a superuser, so one SQL injection or rogue AI command can drop everything. How Postgres roles, privileges, schemas and default privileges work, and a practical setup with separate owner, app and read-only roles.
Postgres Read Replicas: Streaming Replication, Lag, and Read-Your-Writes
How Postgres physical streaming replication works, sync vs async, measuring replication lag, query conflicts and hot_standby_feedback, routing reads in your app without breaking read-your-writes, replication slots that fill disks, and when a replica is the wrong fix.
Postgres MVCC Explained: Tuples, xmin/xmax, Snapshots and Why VACUUM Exists
How PostgreSQL lets readers and writers work without blocking each other: every UPDATE writes a new row version, transactions see a snapshot, and visibility is decided by xmin and xmax. See it with real queries, and how it explains bloat, VACUUM, HOT updates, long transactions and wraparound.
Postgres Index Types: B-tree, GIN, GiST, BRIN, Hash — and When Each Wins
Postgres has more index types than most databases, and choosing well can turn a sequential scan into milliseconds. How B-tree, GIN, GiST, SP-GiST, BRIN and hash indexes work, which operators each supports, partial and expression indexes, covering indexes, and how to verify the planner uses them.
Playwright Tutorial: End-to-End Tests That Aren't Flaky
Playwright drives real browsers to test your app the way users use it. Install it, write your first test, use role-based locators and auto-waiting assertions, log in once and reuse the session, run against a dev server, debug with UI mode and traces, and run it in CI.
PID 1 in Containers: Signals, Zombies, and Why Your Container Won't Stop
Inside a container your app is PID 1, and PID 1 is special: the kernel won't apply default signal handlers to it and it must reap orphaned children. Why docker stop takes 10 seconds, why shell-form CMD swallows SIGTERM, zombies, and the fixes: exec form, tini/--init, signal handling.
"Command Not Found": The PATH Variable Explained
"command not found" or "is not recognized as an internal or external command" usually means the program is installed but your terminal doesn't know where to look. How PATH works on Mac, Linux and Windows, how to check it, and how to add a folder permanently.
What Is package-lock.json? (And Should You Commit It?)
package.json says which versions your app accepts; package-lock.json records exactly which versions were installed. Why the lock file exists, why you should commit it, npm install vs npm ci, fixing merge conflicts in it, and the equivalent files for pnpm, Yarn and Bun.
Optimistic vs Pessimistic Locking: Preventing Lost Updates
Two users edit the same record and one silently overwrites the other. Pessimistic locking (SELECT FOR UPDATE) blocks the second writer; optimistic locking (a version column) detects the conflict. How each works, code for both, atomic updates that avoid locks entirely, and how to choose.
OpenAI API vs Claude API: Which Should Your App Use?
Both APIs let your app send text (and images) to a model and get an answer back. How they differ in request shape, models, tool calling, structured output, caching and pricing — and why many apps keep the choice swappable instead of picking forever.