Cache POST requests
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Cache POST requests

Cache POST requests using the Cache API.

Last updated Apr 23, 2026 If you want to get started quickly, click on the button below.

This creates a repository in your GitHub account and deploys the application to Cloudflare Workers.

export default {
    async fetch(request, env, ctx) {
        async function sha256(message) {
            // encode as UTF-8
            const msgBuffer = await new TextEncoder().encode(message);
            // hash the message
            const hashBuffer = await crypto.subtle.digest("SHA-256", msgBuffer);
            // convert bytes to hex string
            return [...new Uint8Array(hashBuffer)]
                .map((b) => b.toString(16).padStart(2, "0"))
                .join("");
        }
        try {
            if (request.method.toUpperCase() === "POST") {
                const body = await request.clone().text();
                // Hash the request body to use it as a part of the cache key
                const hash = await sha256(body);
                const cacheUrl = new URL(request.url);
                // Store the URL in cache by prepending the body's hash
                cacheUrl.pathname = "/posts" + cacheUrl.pathname + hash;
                // Convert to a GET to be able to cache
                const cacheKey = new Request(cacheUrl.toString(), {
                    headers: request.headers,
                    method: "GET",
                });

                const cache = caches.default;
                // Find the cache key in the cache
                let response = await cache.match(cacheKey);
                // Otherwise, fetch response to POST request from origin
                if (!response) {
                    response = await fetch(request);
                    ctx.waitUntil(cache.put(cacheKey, response.clone()));
                }
                return response;
            }
            return fetch(request);
        } catch (e) {
            return new Response("Error thrown " + e.message);
        }
    },
};

interface Env {}
export default {
    async fetch(request, env, ctx): Promise<Response> {
        async function sha256(message) {
            // encode as UTF-8
            const msgBuffer = await new TextEncoder().encode(message);
            // hash the message
            const hashBuffer = await crypto.subtle.digest("SHA-256", msgBuffer);
            // convert bytes to hex string
            return [...new Uint8Array(hashBuffer)]
                .map((b) => b.toString(16).padStart(2, "0"))
                .join("");
        }
        try {
            if (request.method.toUpperCase() === "POST") {
                const body = await request.clone().text();
                // Hash the request body to use it as a part of the cache key
                const hash = await sha256(body);
                const cacheUrl = new URL(request.url);
                // Store the URL in cache by prepending the body's hash
                cacheUrl.pathname = "/posts" + cacheUrl.pathname + hash;
                // Convert to a GET to be able to cache
                const cacheKey = new Request(cacheUrl.toString(), {
                    headers: request.headers,
                    method: "GET",
                });

                const cache = caches.default;
                // Find the cache key in the cache
                let response = await cache.match(cacheKey);
                // Otherwise, fetch response to POST request from origin
                if (!response) {
                    response = await fetch(request);
                    ctx.waitUntil(cache.put(cacheKey, response.clone()));
                }
                return response;
            }
            return fetch(request);
        } catch (e) {
            return new Response("Error thrown " + e.message);
        }
    },
} satisfies ExportedHandler<Env>;

import hashlib
from workers import WorkerEntrypoint
from pyodide.ffi import create_proxy
from js import fetch, URL, Headers, Request, caches

class Default(WorkerEntrypoint):
    async def fetch(self, request, _, ctx):
        if 'POST' in request.method:
            # Hash the request body to use it as a part of the cache key
            body = await request.clone().text()
            body_hash = hashlib.sha256(body.encode('UTF-8')).hexdigest()

            # Store the URL in cache by prepending the body's hash
            cache_url = URL.new(request.url)
            cache_url.pathname = "/posts" + cache_url.pathname + body_hash

            # Convert to a GET to be able to cache
            headers = Headers.new(dict(request.headers).items())
            cache_key = Request.new(cache_url.toString(), method='GET', headers=headers)

            # Find the cache key in the cache
            cache = caches.default
            response = await cache.match(cache_key)

            # Otherwise, fetch response to POST request from origin
            if response is None:
                response = await fetch(request)
                ctx.waitUntil(create_proxy(cache.put(cache_key, response.clone())))

            return response

        return fetch(request)

import { Hono } from "hono";
import { sha256 } from "hono/utils/crypto";

const app = new Hono();

// Middleware for caching POST requests
app.post("*", async (c) => {
    try {
        // Get the request body
        const body = await c.req.raw.clone().text();

        // Hash the request body to use it as part of the cache key
        const hash = await sha256(body);

        // Create the cache URL
        const cacheUrl = new URL(c.req.url);

        // Store the URL in cache by prepending the body's hash
        cacheUrl.pathname = "/posts" + cacheUrl.pathname + hash;

        // Convert to a GET to be able to cache
        const cacheKey = new Request(cacheUrl.toString(), {
            headers: c.req.raw.headers,
            method: "GET",
        });

        const cache = caches.default;

        // Find the cache key in the cache
        let response = await cache.match(cacheKey);

        // If not in cache, fetch response to POST request from origin
        if (!response) {
            response = await fetch(c.req.raw);
            c.executionCtx.waitUntil(cache.put(cacheKey, response.clone()));
        }

        return response;
    } catch (e) {
        return c.text("Error thrown " + e.message, 500);
    }
});

// Handle all other HTTP methods
app.all("*", (c) => {
    return fetch(c.req.raw);
});

export default app;

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description: Send Additional Cache Tags using Workers title: Cache Tags using Workers image: https://developers.cloudflare.com/workers/examples/cache-tags/og.png?v=c28dfb8fbf80c9c5

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Cache POST requests

Cache POST requests

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