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2026-07-29 16:01
REST API

ETag Caching

CacheRequestValidateHard
Try Interactive Demo

What you will learn

  • Send If-None-Match and verify 304 Not Modified — this is how caches stay fresh
  • Test weak vs strong ETags — they compare differently and protect against different bugs
  • Verify ETag changes on every content change — otherwise caches serve stale data

Description

Use ETags for conditional requests and cache validation.

Test Scenario

const response1 = await request.get('/api/v1/etag');
const etag = response1.headers()['etag'];

const response2 = await request.get('/api/v1/etag', {
  headers: { 'If-None-Match': etag }
});
expect(response2.status()).toBe(304);
Endpoint/api/v1/etag

Testing Tips

  • •GET returns ETag header
  • •Use If-None-Match for conditional GET
  • •Check 304 Not Modified response
// Playwright API Testing - REST
import { test, expect } from '@playwright/test';


test('REST API request', async ({ request }) => {
  const response = await request.get('/api/v1/resource');


  expect(response.ok()).toBeTruthy();
  expect(response.status()).toBe(200);


  const data = await response.json();
  expect(data).toBeDefined();
});

Challenge ID: rest-etag-caching

2 frameworks available

API Playground

Send requests and inspect responses

Endpoint: /api/v1/etag

Press Enter to send