diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 7c40ea8..90f7710 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -19,6 +19,7 @@ jobs:
               uses: shivammathur/setup-php@v2
               with:
                   php-version: '8.2'
+                  extensions: apcu
               env:
                   fail-fast: true
 
diff --git a/README.md b/README.md
index abe845c..d8bcde2 100644
--- a/README.md
+++ b/README.md
@@ -208,10 +208,14 @@ name in the PHP class.
 ## Caching
 
 You can (**and should**) cache the PKL modules to improve performance. This is especially useful when evaluating the same PKL file
-multiple times. You can use the `warmup` command to dump the PKL modules to a cache file. Phikl will then use the cache file automatically when evaluating a PKL file. If the PKL file is not found in the cache, Phikl will evaluate the PKL file on the go.
+multiple times.
 
 **⚠️ Using Phikl with the cache avoids the PKL CLI tool to be executed to evaluate modules and should be done when deploying your application for better performances.**
 
+### Warmup the Cache
+
+You can use the `warmup` command to dump the PKL modules to a cache file by default. Phikl will then use the cache file automatically when evaluating a PKL file. If the PKL file is not found in the cache, Phikl will evaluate the PKL file on the go.
+
 Phikl will go through all `.pkl` files of your project and dump them to the cache file.
 
 Here's an example of how to use the `warmup` command:
@@ -240,4 +244,11 @@ Here are a few things to note about Phikl cache:
 - Phikl will automatically refresh the cache if a PKL module is modified since last warmup
 - Any corrupted cache entry will be automatically refreshed
 
+### Cache Backends
+
 If you have your own cache system, you can use the `Pkl::setCache()` method to set the cache system to use. You can pass it any instance of compliant PSR-16 cache system implementing `Psr\SimpleCache\CacheInterface`. This is useful you want to use, for example, a Redis server as a cache system for your Pkl modules.
+
+Phikl comes with the following cache backends:
+
+ * `PersistentCache`, which is the default one used by Phikl. It uses a file to store the cache.
+ * `APCuCache`, which uses the APCu extension to store the cache in memory.
diff --git a/src/Cache/ApcuCache.php b/src/Cache/ApcuCache.php
new file mode 100644
index 0000000..f20300f
--- /dev/null
+++ b/src/Cache/ApcuCache.php
@@ -0,0 +1,109 @@
+<?php
+
+namespace Phikl\Cache;
+
+use Psr\SimpleCache\CacheInterface;
+
+/**
+ * Simple implementation of the PSR-16 CacheInterface using APCu
+ * for the Pkl modules evaluation cache.
+ */
+final class ApcuCache implements CacheInterface
+{
+    /**
+     * @param non-empty-string $key
+     */
+    public function get(string $key, mixed $default = null): Entry|null
+    {
+        if ($default !== null && !$default instanceof Entry) {
+            throw new \InvalidArgumentException('Default value must be null or an instance of Entry');
+        }
+
+        $entry = \apcu_fetch($key);
+        if ($entry === false) {
+            return $default;
+        }
+
+        $entry = @unserialize($entry);
+        if ($entry === false) {
+            return $default;
+        }
+
+        return $entry;
+    }
+
+    public function set(string $key, mixed $value, \DateInterval|int|null $ttl = null): bool
+    {
+        if (!$value instanceof Entry) {
+            return false;
+        }
+
+        return \apcu_store(
+            $key,
+            serialize($value),
+            $ttl instanceof \DateInterval ? (int) ($ttl->format('U')) - \time() : ($ttl ?? 0)
+        );
+    }
+
+    public function delete(string $key): bool
+    {
+        return \apcu_delete($key);
+    }
+
+    /**
+     * Caution, this method will clear the entire cache, not just the cache for this application.
+     */
+    public function clear(): bool
+    {
+        return \apcu_clear_cache();
+    }
+
+    /**
+     * @param iterable<non-empty-string> $keys
+     *
+     * @return array<non-empty-string, Entry|null>
+     */
+    public function getMultiple(iterable $keys, mixed $default = null): array
+    {
+        $entries = [];
+        foreach ($keys as $key) {
+            $entries[$key] = $this->get($key, $default);
+        }
+
+        return $entries;
+    }
+
+    /**
+     * @param iterable<string, Entry> $values
+     */
+    public function setMultiple(iterable $values, \DateInterval|int|null $ttl = null): bool
+    {
+        foreach ($values as $key => $value) {
+            if (!$this->set($key, $value, $ttl)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * @param iterable<string> $keys
+     */
+    public function deleteMultiple(iterable $keys): bool
+    {
+        $success = true;
+        foreach ($keys as $key) {
+            if (!$this->delete($key)) {
+                $success = false;
+            }
+        }
+
+        return $success;
+    }
+
+    public function has(string $key): bool
+    {
+        return \apcu_exists($key);
+    }
+}
diff --git a/src/Cache/PersistentCache.php b/src/Cache/PersistentCache.php
index bd3eb4e..aa0ac38 100644
--- a/src/Cache/PersistentCache.php
+++ b/src/Cache/PersistentCache.php
@@ -13,6 +13,10 @@
 use Phikl\Exception\EmptyCacheException;
 use Psr\SimpleCache\CacheInterface;
 
+/**
+ * Simple implementation of the PSR-16 CacheInterface using a file for
+ * Pkl modules evaluation cache.
+ */
 final class PersistentCache implements CacheInterface
 {
     private const DEFAULT_CACHE_FILE = '.phikl.cache';
diff --git a/tests/Cache/ApcuCacheTest.php b/tests/Cache/ApcuCacheTest.php
new file mode 100644
index 0000000..bf97be8
--- /dev/null
+++ b/tests/Cache/ApcuCacheTest.php
@@ -0,0 +1,147 @@
+<?php
+
+namespace Cache;
+
+use Phikl\Cache\ApcuCache;
+use Phikl\Cache\Entry;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\RequiresPhpExtension;
+use PHPUnit\Framework\TestCase;
+
+#[RequiresPhpExtension('apcu')]
+#[CoversClass(ApcuCache::class)]
+class ApcuCacheTest extends TestCase
+{
+    protected function tearDown(): void
+    {
+        \apcu_clear_cache();
+    }
+
+    public function testGetWithDefaultOtherThanEntryInstance(): void
+    {
+        $cache = new ApcuCache();
+
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('Default value must be null or an instance of Entry');
+
+        $cache->get('key', 'invalid');
+    }
+
+    public function testGetReturnsDefaultIfKeyDoesNotExist(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry = new Entry('content', 'hash', 0);
+
+        $this->assertNull($cache->get('nonexistent'));
+        $this->assertSame($entry, $cache->get('nonexistent', $entry));
+        $this->assertFalse($cache->has('nonexistent'));
+    }
+
+    public function testGetOnValidSetEntry(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry = new Entry('content', 'hash', $time = \time());
+        $cache->set('key', $entry);
+
+        $entry = $cache->get('key');
+        $this->assertInstanceOf(Entry::class, $entry);
+        $this->assertSame('content', $entry->content);
+        $this->assertSame('hash', $entry->hash);
+        $this->assertSame($time, $entry->timestamp);
+    }
+
+    public function testSetReturnsFalseOnInvalidEntry(): void
+    {
+        $cache = new ApcuCache();
+
+        $this->assertFalse($cache->set('key', 'invalid'));
+    }
+
+    public function testDeleteEntry(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry = new Entry('content', 'hash', 0);
+        $cache->set('key', $entry);
+
+        $this->assertTrue($cache->delete('key'));
+        $this->assertNull($cache->get('key'));
+    }
+
+    public function testClear(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry = new Entry('content', 'hash', 0);
+        $cache->set('key', $entry);
+
+        $this->assertTrue($cache->clear());
+        $this->assertNull($cache->get('key'));
+    }
+
+    public function testGetSetMultiple(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry1 = new Entry('content1', 'hash1', 0);
+        $entry2 = new Entry('content2', 'hash2', 0);
+        $entry3 = new Entry('content3', 'hash3', 0);
+
+        $cache->setMultiple([
+            'key1' => $entry1,
+            'key2' => $entry2,
+            'key3' => $entry3,
+        ]);
+
+        $entries = $cache->getMultiple(['key1', 'key2', 'key3']);
+
+        $this->assertArrayHasKey('key1', $entries);
+        $this->assertArrayHasKey('key2', $entries);
+        $this->assertArrayHasKey('key3', $entries);
+
+        $this->assertInstanceOf(Entry::class, $entries['key1']);
+        $this->assertSame('content1', $entries['key1']->content);
+        $this->assertSame('hash1', $entries['key1']->hash);
+
+        $this->assertInstanceOf(Entry::class, $entries['key2']);
+        $this->assertSame('content2', $entries['key2']->content);
+        $this->assertSame('hash2', $entries['key2']->hash);
+
+        $this->assertInstanceOf(Entry::class, $entries['key3']);
+        $this->assertSame('content3', $entries['key3']->content);
+        $this->assertSame('hash3', $entries['key3']->hash);
+    }
+
+    public function testDeleteMultiple(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry1 = new Entry('content1', 'hash1', 0);
+        $entry2 = new Entry('content2', 'hash2', 0);
+        $entry3 = new Entry('content3', 'hash3', 0);
+
+        $cache->setMultiple([
+            'key1' => $entry1,
+            'key2' => $entry2,
+            'key3' => $entry3,
+        ]);
+
+        $this->assertTrue($cache->deleteMultiple(['key1', 'key2']));
+        $this->assertNull($cache->get('key1'));
+        $this->assertNull($cache->get('key2'));
+        $this->assertNotNull($cache->get('key3'));
+    }
+
+    public function testHas(): void
+    {
+        $cache = new ApcuCache();
+
+        $entry = new Entry('content', 'hash', 0);
+        $cache->set('key', $entry);
+
+        $this->assertTrue($cache->has('key'));
+        $this->assertFalse($cache->has('invalid'));
+    }
+}