HTTP

Topic Cluster

HTTP Performance

Caching, compression, connection behavior, and practical latency optimization topics.

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HTTP Status Codes

103 Early Hints

The server sends preliminary response headers to help the client start preloading resources. Learn how 103 Early Hints improves page load performance.

 HTTP Status Codes

304 Not Modified

Cached response is still valid. Learn how 304 Not Modified improves performance through conditional requests and caching.

 HTTP Status Codes

HTTP 429 Too Many Requests: Rate Limiting

Learn what 429 Too Many Requests means, how rate limiting works, and how to handle API throttling in your applications.

 HTTP Headers

Accept-Encoding Header

Learn how Accept-Encoding tells servers which compression formats (gzip, br, deflate) your client supports to reduce bandwidth and speed up page loads.

 HTTP Headers

Accept-Ranges Header

Learn how the Accept-Ranges header tells clients whether your server supports partial content requests (byte ranges) for efficient downloads and streaming.

 HTTP Headers

Access-Control-Max-Age Header

Learn how Access-Control-Max-Age specifies how long browsers can cache CORS preflight results. Reduce preflight requests and improve cross-origin performance.

 HTTP Headers

Age Header

Learn how the Age header indicates how long a response has been cached in seconds. Understand cache freshness calculations and CDN behavior.

 HTTP Headers

Cache-Control Header: Complete HTTP Caching Guide

Master the Cache-Control header. Learn how to control browser and CDN caching with max-age, no-cache, no-store, and other directives.

 HTTP Headers

Content-Encoding

Learn how Content-Encoding specifies compression algorithms (gzip, br, deflate) used to encode response bodies. Reduce bandwidth and improve load times.

 HTTP Headers

Content-Range Header

Learn how the Content-Range header indicates which portion of a resource is being sent in partial content (206) responses for range requests and streaming.

 HTTP Headers

Early-Hints

Learn how 103 Early Hints allows servers to send preload hints while preparing the main response. Improve page load performance with early resource loading.

 HTTP Headers

ETag

Learn how the ETag header provides a unique identifier for resource versions, enabling efficient cache validation and conditional requests to reduce bandwidth.

 HTTP Headers

Expires Header

Learn how the Expires header specifies when cached responses become stale. Understand date formats and when to use Expires vs Cache-Control for caching.

 HTTP Headers

If-Match Header

Learn how the If-Match header makes requests conditional based on ETag matching. Prevent conflicts and lost updates in concurrent editing scenarios.

 HTTP Headers

If-Modified-Since Header

Learn how the If-Modified-Since header requests resources only if modified since a specific date. Reduce bandwidth with efficient conditional caching.

 HTTP Headers

If-None-Match Header

Learn how the If-None-Match header makes conditional requests using ETags. Avoid downloading unchanged resources and reduce bandwidth with cache validation.

 HTTP Headers

If-Range Header

Learn how the If-Range header requests partial content only if the resource is unchanged. Efficiently resume downloads without re-fetching entire files.

 HTTP Headers

If-Unmodified-Since Header

Learn how the If-Unmodified-Since header makes requests conditional on resources not being modified. Prevent conflicts in concurrent update scenarios.

 HTTP Headers

Keep-Alive Header

Learn how the Keep-Alive header controls HTTP connection persistence and reuse. Reduce latency and improve performance by avoiding repeated TCP handshakes.

 HTTP Headers

Last-Modified

Learn how the Last-Modified header indicates when a resource was last changed. Enable efficient cache validation with If-Modified-Since conditional requests.

 HTTP Headers

Link Header

Learn how the Link header provides resource hints and enables preloading of CSS, fonts, and scripts to improve page load performance and user experience.

 HTTP Headers

Performance-Timing

Learn about Performance-Timing, a non-standard header for exposing server-side performance metrics to clients. Understand its use cases and alternatives.

 HTTP Headers

Range Header

Learn how the Range header requests partial content from servers to enable resumable downloads, video streaming, and efficient large file transfers.

 HTTP Headers

Server-Timing Header

Learn how the Server-Timing header communicates server-side performance metrics to browsers. Analyze backend timing, database queries, and optimize performance.

 HTTP Headers

Timing-Allow-Origin

Learn how the Timing-Allow-Origin header specifies which origins can access Resource Timing API data. Enable cross-origin performance monitoring securely.

 HTTP Headers

Vary

Learn how the Vary header specifies which request headers affect the response. Essential for proper cache differentiation and content negotiation.

 HTTP Headers

X-Cache Header

Learn how the X-Cache header indicates cache hit or miss status from CDNs and proxies. Debug caching issues and verify CDN configuration with this header.

 HTTP Headers

X-Response-Time

Learn how the X-Response-Time header indicates server processing time in milliseconds. Useful for performance monitoring and debugging slow requests.

 Guides

HTTP Headers and Caching: A Practical Guide

Master HTTP caching with Cache-Control, ETag, Last-Modified, and conditional request headers. Learn how to optimize performance with proper cache strategies.

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Core HTTP primitives and baseline concepts every web engineer should know.

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Error diagnosis, status code debugging, and production-safe HTTP troubleshooting workflows.

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Security headers, cookie hardening, CORS policy design, and defensive API behavior.

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Auth flows, authorization semantics, credentials handling, and access control patterns.