🗄️
🧪 Simulate
LV2 · Toolooo Standard
Explore → See → Understand → ActUnderstand it. Feature Level describes the depth of the tool experience.

HTTP Cache Lab

Configure Cache-Control, ETag, and Last-Modified headers and simulate how browsers and CDNs actually cache the response.

EngineeringBackendNetworkingAPI
5m
Response headers
Cache-Control: public, max-age=300
ETag: "a1b2c3-etag"

Live: what happens right now

3m
max-age (5m)FRESHSTALE — REVALIDATEFETCH (t=0)HIT · 3m0s10m
Result
At 3m since the first fetch, a request for this resource is a HIT.
Why it matters
Still fresh — served straight from cache with no network request at all.
Action
Drag past max-age (5m) to see it flip from HIT to REVALIDATE, or toggle ETag/Last-Modified to see which validator saves a full re-fetch.

Quick reference — three fixed points in time

✓
Immediately after (1s): HIT
Still fresh — served straight from cache with no network request at all.
✓
Halfway through max-age (3m): HIT
Still fresh — served straight from cache with no network request at all.
ℹ
After max-age expires (8m): REVALIDATE
Stale by the clock, but the ETag allows a cheap conditional check (If-None-Match → maybe 304).
What this tool does and why

Before you start

What

Configure Cache-Control, ETag, and Last-Modified headers and simulate how browsers and CDNs actually cache the response.

Why

Cache-Control, validators, and request state decide whether a response is served, revalidated, or fetched again.

Your Result and Action update in the tool as you change its inputs.

Model note

This browser-side model explains the inputs you choose. Check an important decision against the real system, brief, or production constraints.

Next

Use the result to choose a connected next move.

LLM Output Assurance Decision LabChoose validation, review and failure-handling layers from an AI feature’s explicit risks and constraints.Real-Time Transport Decision LabCompare Polling, Long Polling, SSE, WebSocket and WebTransport against your communication and infrastructure needs.
How this tool stays honest

How it works

Set response caching headers on a mock request and step through what a browser and a CDN would actually do with them — serve from cache, revalidate, or fetch fresh — so HTTP caching semantics stop being guesswork.

Assumptions

The tool runs in your browser and models the information you provide. It does not know facts outside that model.

Limitations

This is a simplified explanatory model, not a load test or production forecast. Real systems can include dependencies, distributions, failures, and feedback loops outside the selected inputs.

Understand HTTP Cache Lab

What this tool helps you understand

Set response caching headers on a mock request and step through what a browser and a CDN would actually do with them — serve from cache, revalidate, or fetch fresh — so HTTP caching semantics stop being guesswork.

When to use it

When reviewing how response headers control browser or shared caching.

Try a scenario

Compare a fresh cache entry with a stale entry carrying a validator. Follow whether the modeled request reuses, revalidates or fetches the response.

How to read the result

Compare the shape and direction of different scenarios. The useful signal is how the result changes when an input changes, rather than one isolated number.

Assumptions and limits

This is a simplified explanatory model, not a load test or production forecast. Real systems can include dependencies, distributions, failures, and feedback loops outside the selected inputs.

Toolooo is part of Khizooology, created byKhizar Imtiaz (khizooo).