Comparisons
HTTP Side-by-Side
Confused by similar-sounding HTTP concepts? These comparisons cut through the ambiguity with concrete differences, use cases, and decision rules.
- 200 OK vs 204 No Content
200 vs 201 vs 204: Which Success Code to Return
Choose between 200 OK, 201 Created and 204 No Content for REST APIs: what each means, the Location and body rules, raw responses for POST, PUT, PATCH and DELETE.
- 301 Moved Permanently vs 302 Found
301 vs 302 Redirects
Understand the difference between 301 Moved Permanently and 302 Found redirects. Learn when to use each, how browsers cache them, and their SEO implications.
- 301 Moved Permanently vs 308 Permanent Redirect
301 vs 308: Permanent Redirects and POST Requests
301 vs 308: both signal a permanent move, but only 308 preserves POST. Compare browser handling, Google indexing, cache controls, and curl traces.
- 302 Found vs 307 Temporary Redirect
302 vs 307 Redirects
Compare 302 Found and 307 Temporary Redirect, including method preservation, request bodies, browser behavior, caching, and safe API redirect choices.
- 304 Not Modified vs 200 OK
304 Not Modified vs 200 OK
Understand when servers return 304 Not Modified instead of 200 OK. Learn how conditional requests, ETags, and Last-Modified headers enable efficient HTTP caching.
- 400 Bad Request vs 422 Unprocessable Content
400 vs 422: Malformed vs Invalid Requests
400 Bad Request or 422 Unprocessable Content for validation errors? The syntax-vs-semantics rule, what Rails, Laravel, FastAPI and Spring return by default, and raw examples.
- 401 Unauthorized vs 403 Forbidden
401 vs 403: Authentication vs Authorization
Understand the difference between 401 Unauthorized and 403 Forbidden. Learn when each status code applies, common mistakes, and how to use them correctly in APIs.
- 403 Forbidden vs 404 Not Found
403 vs 404: Forbidden or Not Found
403 Forbidden vs 404 Not Found: when to admit a resource exists, when to hide it, the GitHub private-repo example, and the debugging cost of masking 403 as 404.
- 502 Bad Gateway vs 504 Gateway Timeout
502 vs 503 vs 504: Which Gateway Error Is It
502, 503 and 504 side by side: who generated each one, what the upstream did, the nginx error-log line that proves it, and the Cloudflare 52x and ALB equivalents.
- no-cache vs no-store
Cache-Control: no-cache vs no-store
Compare the no-cache and no-store Cache-Control response directives and choose the correct policy for sensitive or frequently changing responses.
- Cookie-Based Auth vs Session-Based Auth
Cookie-Based vs Session-Based Authentication
Compare cookie-based and session-based authentication. Understand where state lives, security tradeoffs, scalability implications, and when to use each approach.
- Cookies vs localStorage / sessionStorage
Cookies vs localStorage vs sessionStorage: What to Use
Cookies vs localStorage vs sessionStorage: request behavior, size limits, expiry, tab scope, partitioning, XSS and CSRF risks, and auth token choices.
- CORS vs CSP
CORS vs CSP
Understand the difference between CORS and Content Security Policy. Both are browser security mechanisms but they protect against completely different threats.
- CORS vs CSRF Protection
CORS vs CSRF: Response Reads vs Forged Writes
CORS controls cross-origin response reads; CSRF abuses automatically sent credentials. Compare preflights, SameSite, tokens, Origin and Sec-Fetch-Site.
- ETag vs Last-Modified
ETag vs Last-Modified: HTTP Cache Validators
ETag vs Last-Modified: strong and weak validation, one-second timestamps, conditional request precedence, multi-server consistency, and CDN debugging.
- GET vs POST
GET vs POST
Understand the fundamental differences between GET and POST HTTP methods. Learn about safety, idempotency, caching, request bodies, and when to use each.
- HTTP vs HTTPS
HTTP vs HTTPS: What TLS Adds and What It Does Not Hide
HTTP vs HTTPS: what TLS encrypts and authenticates, what still leaks (IP, SNI, sizes), where ECH stands, HSTS, mixed content, and the SEO effect of moving to HTTPS.
- HTTP/1.1 vs HTTP/2
HTTP/1.1 vs HTTP/2
Compare HTTP/1.1 and HTTP/2. Understand multiplexing, header compression, server push, and when upgrading to HTTP/2 actually improves performance.
- HTTP/2 vs HTTP/3
HTTP/2 vs HTTP/3: TCP, QUIC and Fallback
Compare HTTP/2 over TCP with HTTP/3 over QUIC: packet loss, stream blocking, connection migration, 0-RTT replay, discovery and curl fallback checks.
- JWT Bearer Token vs Opaque Session Cookie
JWT vs Session Cookies: Logout and Security
Compare stateless JWT bearer tokens with opaque session cookies: revocation, rotation, request size, browser storage, CSRF, XSS and algorithm validation.
- Permissions-Policy vs Feature-Policy
Permissions-Policy vs Feature-Policy
Understand the differences between Permissions-Policy and Feature-Policy headers. Compare syntax changes for geolocation, microphone, camera directives and learn how to migrate.
- PUT vs PATCH
PUT vs PATCH
Understand the difference between PUT and PATCH HTTP methods. Learn when to use full replacement vs partial update, and how each affects idempotency and API design.
- PUT vs POST
PUT vs POST: Create or Replace a Resource
PUT vs POST in REST APIs: who picks the URL, idempotency, retries, upsert, and raw requests showing when to create with POST and when to replace with PUT.
- Server-Sent Events vs WebSockets
SSE vs WebSockets vs Long Polling
Server-Sent Events vs WebSockets vs long polling: direction, reconnects with Last-Event-ID, the 6-connection limit and HTTP/2, nginx proxy buffering, and RFC 8441.