Pragma Cache Inspect

Analyze cache-related headers across layers. No input is sent to a server. Use it for first-pass revalidation and CDN mismatch troubleshooting.

Status

Runs in your browser. No input is sent to a server. Use this as a first-pass diagnostic step.

How to use

Paste Pragma or Request/Response Headers and click “Parse”. It summarizes directives like no-cache.

Notes (this tool)

  • Accepts Pragma: header lines (multi-line paste is OK).

About this page

What does this tool do?

Split Pragma to list directives such as no-cache.

Useful for checking legacy cache control behavior.

Basics (role of Pragma)

  • Pragma: no-cache is a legacy HTTP/1.0 directive.
  • Cache-Control is the modern primary control.
  • Pragma is often seen on requests.

Input examples

  • Pragma: no-cache
  • Paste full Request Headers

Relation to Cache-Control

Both may appear for compatibility, but Cache-Control is the modern authority.

Common pitfalls

  • Assuming Pragma alone controls caching
  • Conflicting values with Cache-Control

Debugging workflow (recommended)

  • Check modern policy with Cache-Control Inspect
  • Summarize Pragma here
  • Check other cache headers like Vary/Age
  • Cache-Control Inspect
  • Expires Inspect
  • Age Inspect

Recommendations (practical)

  • Use Cache-Control as primary; Pragma is legacy
  • Pair Pragma: no-cache with Cache-Control: no-cache
  • Check Expires/Age alongside responses

What this tool does

  • Summarize Pragma values
  • Clarify relation to Cache-Control

Operational notes

  • Cache behavior changes across browser, CDN, and proxy layers, so compare captures from the same observation point.
  • Header-only diagnosis may be insufficient. Also review application cache invalidation strategy and key design.

Referenced specs

  • RFC 9110 (HTTP Semantics)
  • MDN: Pragma

FAQ

Is Pragma alone enough for cache control?

No. Modern control should rely on Cache-Control, with Pragma mainly for compatibility.

Are Pragma: no-cache and Cache-Control: no-cache identical?

They have similar intent but differ in origin and behavior scope. Design primarily around Cache-Control.

References

  1. RFC 9110
  2. MDN: Pragma

These links are generated from site_map rules in recommended diagnostic order.

  1. ETag Policy Checker — Check ETag operational policy consistency
  2. ETag Builder — Build ETag values for testing and operations
  3. If-Match Inspect — Parse If-Match and inspect update preconditions
  4. Cache Validator Overview — Summarize relationships among ETag/Last-Modified validators
  5. Cache Not Working Troubleshooting — Troubleshoot cache-not-working symptoms step by step from headers
  6. HTTP Cache Mismatch — Identify root causes of cache mismatches
  7. Cache Response Analyzer — Judge cacheability from response headers
  8. Cache Key Inspect — Visualize cache-key splits from URL, Vary, and headers

Cache Control

Diagnose delivery policy across Cache-Control/Expires/Age