# HTTP Cache-Control CDN Edge TTL Budget Optimizer Analyze Cache-Control directives, calculate browser/shared-cache TTL and stale budgets, detect directive conflicts, and compare static behavior notes for generic HTTP, Fastly, Cloudflare, and Akamai. > Canonical page: https://elysiatools.com/en/tools/http-cache-control-cdn-edge-ttl-budget-optimizer - **Category:** Development - **Keywords:** cache-control, cdn, ttl, s-maxage, stale-while-revalidate, stale-if-error, fastly, cloudflare, akamai, http cache ## Overview Analyze an HTTP Cache-Control header to calculate browser and shared-cache TTLs, review stale budgets, detect directive conflicts, and compare static behavior notes for generic HTTP, Fastly, Cloudflare, and Akamai. ## Inputs - **Cache-Control 头** (textarea): public, max-age=60, s-maxage=600, stale-while-revalidate=30 - **CDN** (select) - **浏览器 TTL 预算（秒，可选）** (number) - **边缘 TTL 预算（秒，可选）** (number) - **Stale 预算（秒，可选）** (number) ## When to use - Check whether browser and CDN freshness periods match your caching requirements. - Compare max-age, s-maxage, stale-while-revalidate, and stale-if-error budgets with defined limits. - Investigate conflicting directives such as private, public, no-cache, and no-store. ## How it works - Enter a Cache-Control header, such as `public, max-age=60, s-maxage=600, stale-while-revalidate=30`. - Select a CDN context or use Generic HTTP for a general analysis. - Optionally enter browser TTL, edge TTL, and stale budgets in seconds. - Review the calculated TTLs, stale windows, directive conflicts, and static CDN behavior notes. ## Use cases - Validate cache headers for public web pages and APIs before deployment. - Set separate browser and edge freshness budgets for CDN-delivered content. - Review stale serving behavior and cache directive conflicts during performance or reliability audits. ## Frequently asked questions ### What input does this tool require? Enter a Cache-Control header in the required text field. ### What does max-age represent? max-age specifies the freshness lifetime for browsers and other private caches, in seconds. ### What does s-maxage represent? s-maxage specifies the freshness lifetime for shared caches such as CDN edge caches, in seconds. ### Can I check stale-while-revalidate and stale-if-error? Yes. The analyzer reviews stale directives and compares their budgets when you provide a stale budget. ### Which CDN options are available? You can select Generic HTTP, Fastly, Cloudflare, or Akamai for static behavior notes. ## Related tools - [Pump NPSH (Net Positive Suction Head) Calculator & Cavitation Check](https://elysiatools.com/en/tools/pump-npsh-calculator): Compute the available Net Positive Suction Head (NPSH_a) of a pump and compare it against the required NPSH (NPSH_r) from the pump curve. Head-balance form: NPSH_a = (p_surface_abs - p_vapor) / (ρ·g) + H_static - h_friction. 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