diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8a6dc28189..25878e7083 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -396,11 +396,23 @@ jobs:
         if: matrix.build_playground
         run: yarn workspace playground test
 
+      - name: Setup Rclone
+        if: ${{ matrix.build_playground && startsWith(github.ref, 'refs/tags/v') }}
+        uses: cometkim/rclone-actions/setup-rclone@89de8311dd0ca0b43143329d3daeb1041852ad9f
+
+      - name: Configure Rclone remote
+        if: ${{ matrix.build_playground && startsWith(github.ref, 'refs/tags/v') }}
+        uses: cometkim/rclone-actions/configure-remote/s3-provider@89de8311dd0ca0b43143329d3daeb1041852ad9f
+        with:
+          name: rescript
+          provider: Cloudflare
+          endpoint: ${{ vars.CLOUDFLARE_ACCOUNT_ID }}.r2.cloudflarestorage.com
+          access-key-id: ${{ secrets.CLOUDFLARE_R2_ACCESS_KEY_ID }}
+          secret-access-key: ${{ secrets.CLOUDFLARE_R2_SECRET_ACCESS_KEY }}
+          acl: private
+
       - name: Upload playground compiler to CDN
         if: ${{ matrix.build_playground && startsWith(github.ref, 'refs/tags/v') }}
-        env:
-          KEYCDN_USER: ${{ secrets.KEYCDN_USER }}
-          KEYCDN_PASSWORD: ${{ secrets.KEYCDN_PASSWORD }}
         run: yarn workspace playground upload-bundle
 
       - name: "Upload artifacts: binaries"
diff --git a/Makefile b/Makefile
index 99dd18476b..96a166ce9e 100644
--- a/Makefile
+++ b/Makefile
@@ -69,14 +69,14 @@ artifacts: lib
 # Builds the core playground bundle (without the relevant cmijs files for the runtime)
 playground:
 	dune build --profile browser
-	cp ./_build/default/compiler/jsoo/jsoo_playground_main.bc.js packages/playground/compiler.js
+	cp -f ./_build/default/compiler/jsoo/jsoo_playground_main.bc.js packages/playground/compiler.js
 
 # Creates all the relevant core and third party cmij files to side-load together with the playground bundle
 playground-cmijs: artifacts
 	yarn workspace playground build
 
 # Builds the playground, runs some e2e tests and releases the playground to the
-# CDN (requires KEYCDN_USER and KEYCDN_PASSWORD set in the env variables)
+# Cloudflare R2 (requires Rclone `rescript:` remote)
 playground-release: playground playground-cmijs
 	yarn workspace playground test
 	yarn workspace playground upload-bundle
diff --git a/package.json b/package.json
index acb466fad3..ca1418e676 100644
--- a/package.json
+++ b/package.json
@@ -84,9 +84,11 @@
   "devDependencies": {
     "@biomejs/biome": "1.9.4",
     "@types/node": "^20.14.9",
+    "@types/semver": "^7.7.0",
     "@yarnpkg/types": "^4.0.1",
     "mocha": "10.8.2",
     "nyc": "15.0.0",
+    "semver": "^7.7.2",
     "typescript": "5.8.2"
   },
   "workspaces": [
diff --git a/packages/playground/.gitignore b/packages/playground/.gitignore
index f20e8d25e1..e979f5b774 100644
--- a/packages/playground/.gitignore
+++ b/packages/playground/.gitignore
@@ -32,3 +32,5 @@ yarn.lock
 
 /packages/
 /compiler.js
+
+.tmp/
diff --git a/packages/playground/package.json b/packages/playground/package.json
index 0e43a5a4d3..3131ae618f 100644
--- a/packages/playground/package.json
+++ b/packages/playground/package.json
@@ -5,8 +5,8 @@
   "scripts": {
     "clean": "rescript clean",
     "test": "node ./playground_test.cjs",
-    "build": "rescript clean && rescript build && node ./scripts/generate_cmijs.mjs && rollup -c",
-    "upload-bundle": "./scripts/upload_bundle.sh",
+    "build": "rescript clean && rescript build && node scripts/generate_cmijs.mjs && rollup -c",
+    "upload-bundle": "node scripts/upload_bundle.mjs",
     "revalidate": "./scripts/website_update_playground.sh"
   },
   "dependencies": {
diff --git a/packages/playground/scripts/common.mjs b/packages/playground/scripts/common.mjs
new file mode 100644
index 0000000000..f45ea3a51b
--- /dev/null
+++ b/packages/playground/scripts/common.mjs
@@ -0,0 +1,33 @@
+// @ts-check
+
+import * as child_process from "node:child_process";
+import * as path from "node:path";
+
+export const compilerRootDir = path.join(
+  import.meta.dirname,
+  "..",
+  "..",
+  "..",
+);
+
+// The playground-bundling root dir
+export const playgroundDir = path.join(import.meta.dirname, "..");
+
+// Final target output directory where all the cmijs will be stored
+export const playgroundPackagesDir = path.join(playgroundDir, "packages");
+
+/**
+ * @param {string} cmd
+ * @param {child_process.ExecSyncOptions} [opts={}]
+ */
+export function exec(cmd, opts = {}) {
+  console.log(`>>>>>> running command: ${cmd}`);
+  const result = child_process.execSync(cmd, {
+    cwd: playgroundDir,
+    stdio: "inherit",
+    ...opts,
+    encoding: "utf8",
+  });
+  console.log("<<<<<<");
+  return result || "";
+}
diff --git a/packages/playground/scripts/generate_cmijs.mjs b/packages/playground/scripts/generate_cmijs.mjs
index 2fb44d8f05..56b29f50f0 100644
--- a/packages/playground/scripts/generate_cmijs.mjs
+++ b/packages/playground/scripts/generate_cmijs.mjs
@@ -13,92 +13,54 @@
  * playground bundle.
  */
 
-import * as child_process from "node:child_process";
 import * as fs from "node:fs";
 import * as path from "node:path";
 
 import resConfig from "../rescript.json" with { type: "json" };
+import {
+  exec,
+  compilerRootDir,
+  playgroundPackagesDir,
+} from "./common.mjs";
 
-const RESCRIPT_COMPILER_ROOT_DIR = path.join(
-  import.meta.dirname,
-  "..",
-  "..",
-  "..",
-);
+exec("yarn rescript clean");
+exec("yarn rescript");
 
-// The playground-bundling root dir
-const PLAYGROUND_DIR = path.join(import.meta.dirname, "..");
-
-// Final target output directory where all the cmijs will be stored
-const PACKAGES_DIR = path.join(PLAYGROUND_DIR, "packages");
+// We need to build the compiler's builtin modules as a separate cmij.
+// Otherwise we can't use them for compilation within the playground.
+buildCmij(compilerRootDir, "compiler-builtins");
 
-// Making sure this directory exists, since it's not checked in to git
-fs.mkdirSync(PACKAGES_DIR, { recursive: true });
+const packages = resConfig["bs-dependencies"];
+for (const pkgName of packages) {
+  buildCmij(
+    path.join(compilerRootDir, "node_modules", pkgName),
+    pkgName,
+  );
+}
 
 /**
- * @param {string} cmd
+ * @param {string} pkgDir
+ * @param {string} pkgName
  */
-function e(cmd) {
-  console.log(`>>>>>> running command: ${cmd}`);
-  child_process.execSync(cmd, {
-    cwd: PLAYGROUND_DIR,
-    encoding: "utf8",
-    stdio: [0, 1, 2],
-  });
-  console.log("<<<<<<");
-}
-
-e("yarn rescript clean");
-e("yarn rescript");
-
-const packages = resConfig["bs-dependencies"];
-
-// We need to build the compiler's builtin modules as a separate cmij.
-// Otherwise we can't use them for compilation within the playground.
-function buildCompilerCmij() {
-  const rescriptLibOcamlFolder = path.join(
-    RESCRIPT_COMPILER_ROOT_DIR,
+function buildCmij(pkgDir, pkgName) {
+  const libOcamlFolder = path.join(
+    pkgDir,
     "lib",
     "ocaml",
   );
 
-  const outputFolder = path.join(PACKAGES_DIR, "compiler-builtins");
+  const outputFolder = path.join(playgroundPackagesDir, pkgName);
   fs.mkdirSync(outputFolder, { recursive: true });
 
   const cmijFile = path.join(outputFolder, "cmij.js");
-
-  e(
-    `find ${rescriptLibOcamlFolder} -name "*.cmi" -or -name "*.cmj" | xargs -n1 basename | xargs js_of_ocaml build-fs -o ${cmijFile} -I ${rescriptLibOcamlFolder}`,
-  );
+  const inputFiles = fs.readdirSync(libOcamlFolder).filter(isCmij).join(" ");
+  exec(`js_of_ocaml build-fs -o ${cmijFile} -I ${libOcamlFolder} ${inputFiles}`);
 }
 
-function buildThirdPartyCmijs() {
-  for (const pkg of packages) {
-    const libOcamlFolder = path.join(
-      RESCRIPT_COMPILER_ROOT_DIR,
-      "node_modules",
-      pkg,
-      "lib",
-      "ocaml",
-    );
-    const libEs6Folder = path.join(
-      RESCRIPT_COMPILER_ROOT_DIR,
-      "node_modules",
-      pkg,
-      "lib",
-      "es6",
-    );
-    const outputFolder = path.join(PACKAGES_DIR, pkg);
-    fs.mkdirSync(outputFolder, { recursive: true });
-
-    const cmijFile = path.join(outputFolder, "cmij.js");
-
-    e(`find ${libEs6Folder} -name '*.js' -exec cp {} ${outputFolder} \\;`);
-    e(
-      `find ${libOcamlFolder} -name "*.cmi" -or -name "*.cmj" | xargs -n1 basename | xargs js_of_ocaml build-fs -o ${cmijFile} -I ${libOcamlFolder}`,
-    );
-  }
+/**
+ * @param {string} basename 
+ * @return {boolean}
+ */
+function isCmij(basename) {
+  return /\.cm(i|j)$/.test(basename);
 }
-
-buildCompilerCmij();
-buildThirdPartyCmijs();
diff --git a/packages/playground/scripts/upload_bundle.mjs b/packages/playground/scripts/upload_bundle.mjs
new file mode 100644
index 0000000000..265e08837c
--- /dev/null
+++ b/packages/playground/scripts/upload_bundle.mjs
@@ -0,0 +1,129 @@
+#!/usr/bin/env node
+
+// @ts-check
+
+// This script will publish the compiler.js bundle / packages cmij.js files to our Cloudclare R2.
+// The target folder on R2 bucket will be the compiler.js' version number.
+// This script requires `rclone` and `zstd` to be installed.
+
+import * as fs from "node:fs";
+import * as path from "node:path";
+import * as readline from "node:readline/promises";
+import { createRequire } from "node:module";
+import semver from "semver";
+
+import {
+  exec,
+  playgroundDir,
+  playgroundPackagesDir,
+} from "./common.mjs";
+
+const require = createRequire(import.meta.url);
+// @ts-ignore
+const { rescript_compiler } = require('../compiler.js');
+
+/**
+ * @type {number}
+ */
+const version = rescript_compiler.make().rescript.version;
+const tag = "v" + version;
+
+console.log("Uploading playground artifacts for %s", tag);
+if (!process.env.CI) {
+  const rl = readline.createInterface({
+    input: process.stdin,
+    output: process.stdout,
+  });
+  const answer = await rl.question("Do you want to proceed? [y/N]: ");
+  rl.close();
+
+  if (answer.toLowerCase() !== "y") {
+    console.log("Cancelled");
+    process.exit(1);
+  }
+}
+
+const rcloneOpts = (process.env.CI
+  ? [
+    "--stats 5",
+    "--checkers 5000",
+    "--transfers 8",
+    "--buffer-size 128M",
+    "--s3-chunk-size 128M",
+    "--s3-upload-concurrency 8",
+  ]
+  : [
+    "--progress",
+    "--checkers 5000",
+    "--transfers 16",
+    "--buffer-size 128M",
+    "--s3-chunk-size 128M",
+    "--s3-upload-concurrency 16",
+  ]).join(" ");
+
+const remote = process.env.RCLONE_REMOTE || "rescript";
+const bucket = "cdn-assets";
+
+// Create a temporary directory for bundling
+const tmpDir = path.join(playgroundDir, ".tmp");
+const artifactsDir = path.join(tmpDir, tag);
+const archivePath = path.join(tmpDir, `${tag}.tar.zst`);
+fs.rmSync(tmpDir, { recursive: true, force: true });
+fs.mkdirSync(artifactsDir, { recursive: true });
+
+console.log("Copying compiler.js");
+fs.copyFileSync(
+  path.join(playgroundDir, "compiler.js"),
+  path.join(artifactsDir, "compiler.js"),
+);
+
+console.log("Copying packages");
+fs.cpSync(playgroundPackagesDir, artifactsDir, { recursive: true });
+
+// Create tar.zst archive
+console.log("Creating archive...");
+exec(`tar \\
+  --use-compress-program="zstd -T0 --adapt --exclude-compressed" \\
+  -cf "${archivePath}" \\
+  -C "${artifactsDir}" .
+`);
+
+// TODO: This will no longer be needed after the KeyCDN to Cloudflare transition is complete.
+console.log(`Uploading v${version} artifacts...`);
+exec(`rclone sync ${rcloneOpts} --fast-list \\
+  "${artifactsDir}" \\
+  "${remote}:${bucket}/${tag}"
+`);
+
+console.log("Uploading archive...");
+exec(`rclone copyto ${rcloneOpts} \\
+  "${archivePath}" \\
+  "${remote}:${bucket}/playground-bundles/${tag}.tar.zst"
+`);
+
+console.log("Update versions.json");
+{
+  const bundles = exec(
+    `rclone lsf --include="*.tar.zst" rescript:cdn-assets/playground-bundles`,
+    { stdio: ['ignore', 'pipe', 'pipe'] },
+  ).trimEnd().split("\n");
+
+  /** @type {string[]} */
+  let playgroundVersions = [];
+  for (const bundle of bundles) {
+    playgroundVersions.push(bundle.replace(".tar.zst", ""));
+  }
+  playgroundVersions = semver.sort(playgroundVersions);
+
+  console.log('Versions: ', playgroundVersions);
+
+  const versionsPath = path.join(tmpDir, "versions.json");
+  fs.writeFileSync(
+    versionsPath,
+    JSON.stringify(playgroundVersions),
+  );
+  exec(`rclone copyto ${rcloneOpts} \\
+    "${versionsPath}" \\
+    "${remote}:${bucket}/playground-bundles/versions.json"
+  `);
+}
diff --git a/packages/playground/scripts/upload_bundle.sh b/packages/playground/scripts/upload_bundle.sh
deleted file mode 100755
index 28c61ab55e..0000000000
--- a/packages/playground/scripts/upload_bundle.sh
+++ /dev/null
@@ -1,60 +0,0 @@
-#!/usr/bin/env bash
-
-# This script will publish the compiler.js bundle / packages cmij.js files to our KeyCDN server.
-# The target folder on KeyCDN will be the compiler.js' version number.
-# This script requires `curl` / `openssl` to be installed.
-
-SCRIPT_PATH="${BASH_SOURCE[0]}"
-PLAYGROUND_DIR="$(dirname "$(dirname "$SCRIPT_PATH")")"
-
-# Get the actual version from the compiled playground bundle
-VERSION="$(node -e "console.log(require('$PLAYGROUND_DIR/compiler.js').rescript_compiler.make().rescript.version)")"
-
-if [ -z "${KEYCDN_USER}" ]; then
-  echo "KEYCDN_USER environment variable not set. Make sure to set the environment accordingly."
-  exit 1
-fi
-
-if [ -z "${KEYCDN_PASSWORD}" ]; then
-  echo "KEYCDN_PASSWORD environment variable not set. Make sure to set the environment accordingly."
-  exit 1
-fi
-
-KEYCDN_SRV="ftp.keycdn.com"
-NETRC_FILE="${PLAYGROUND_DIR}/.netrc"
-
-# To make sure to not leak any secrets in the bash history, we create a NETRC_FILE
-# with the credentials provided via ENV variables.
-if [ ! -f "${NETRC_FILE}" ]; then
-  echo "No .netrc file found. Creating file '${NETRC_FILE}'"
-  echo "machine ${KEYCDN_SRV} login $KEYCDN_USER password $KEYCDN_PASSWORD" > "${NETRC_FILE}"
-fi
-
-PACKAGES=("compiler-builtins" "@rescript/react")
-
-echo "Uploading compiler.js file..."
-curl --ftp-create-dirs -T "${PLAYGROUND_DIR}/compiler.js" --ssl --tls-max 1.2 --netrc-file $NETRC_FILE ftp://${KEYCDN_SRV}/v${VERSION}/compiler.js
-
-echo "---"
-echo "Uploading packages cmij files..."
-for dir in ${PACKAGES[@]};
-do
-  SOURCE="${PLAYGROUND_DIR}/packages/${dir}"
-  TARGET="ftp://${KEYCDN_SRV}/v${VERSION}/${dir}"
-
-  echo "Uploading '$SOURCE/cmij.js' to '$TARGET/cmij.js'..."
-
-  curl --ftp-create-dirs -T "${SOURCE}/cmij.js" --ssl --tls-max 1.2 --netrc-file $NETRC_FILE "${TARGET}/cmij.js"
-done
-
-# we now upload the bundled stdlib runtime files
-
-DIR="compiler-builtins/stdlib"
-SOURCE="${PLAYGROUND_DIR}/packages/${DIR}"
-TARGET="ftp://${KEYCDN_SRV}/v${VERSION}/${DIR}"
-
-echo "Uploading '$SOURCE/*.js' to '$TARGET/*.js'..."
-
-# we use TLS 1.2 because 1.3 sometimes causes data losses (files capped at 16384B)
-# https://github.com/curl/curl/issues/6149#issuecomment-1618591420
-find "${SOURCE}" -type f -name "*.js" -exec sh -c 'curl --ftp-create-dirs --ssl --tls-max 1.2 --netrc-file "$0" -T "$1" "${2}/$(basename "$1")"' "$NETRC_FILE" {} "$TARGET" \;
diff --git a/yarn.lock b/yarn.lock
index 3749dcd9a2..a0ea540067 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -747,6 +747,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@types/semver@npm:^7.7.0":
+  version: 7.7.0
+  resolution: "@types/semver@npm:7.7.0"
+  checksum: 10c0/6b5f65f647474338abbd6ee91a6bbab434662ddb8fe39464edcbcfc96484d388baad9eb506dff217b6fc1727a88894930eb1f308617161ac0f376fe06be4e1ee
+  languageName: node
+  linkType: hard
+
 "@yarnpkg/types@npm:^4.0.1":
   version: 4.0.1
   resolution: "@yarnpkg/types@npm:4.0.1"
@@ -2483,9 +2490,11 @@ __metadata:
     "@rescript/linux-x64": "workspace:packages/@rescript/linux-x64"
     "@rescript/win32-x64": "workspace:packages/@rescript/win32-x64"
     "@types/node": "npm:^20.14.9"
+    "@types/semver": "npm:^7.7.0"
     "@yarnpkg/types": "npm:^4.0.1"
     mocha: "npm:10.8.2"
     nyc: "npm:15.0.0"
+    semver: "npm:^7.7.2"
     typescript: "npm:5.8.2"
   dependenciesMeta:
     "@rescript/darwin-arm64":
@@ -2685,6 +2694,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"semver@npm:^7.7.2":
+  version: 7.7.2
+  resolution: "semver@npm:7.7.2"
+  bin:
+    semver: bin/semver.js
+  checksum: 10c0/aca305edfbf2383c22571cb7714f48cadc7ac95371b4b52362fb8eeffdfbc0de0669368b82b2b15978f8848f01d7114da65697e56cd8c37b0dab8c58e543f9ea
+  languageName: node
+  linkType: hard
+
 "serialize-javascript@npm:^6.0.2":
   version: 6.0.2
   resolution: "serialize-javascript@npm:6.0.2"