diff --git a/extras/tests/Helpers/Allocators.hpp b/extras/tests/Helpers/Allocators.hpp
index fd6e7b21..a551c311 100644
--- a/extras/tests/Helpers/Allocators.hpp
+++ b/extras/tests/Helpers/Allocators.hpp
@@ -265,12 +265,14 @@ class TimebombAllocator : public ArduinoJson::Allocator {
 }  // namespace
 
 inline size_t sizeofPoolList(size_t n = ARDUINOJSON_INITIAL_POOL_COUNT) {
-  return sizeof(ArduinoJson::detail::MemoryPool) * n;
+  using namespace ArduinoJson::detail;
+  return sizeof(MemoryPool<VariantData>) * n;
 }
 
 inline size_t sizeofPool(
     ArduinoJson::detail::SlotCount n = ARDUINOJSON_POOL_CAPACITY) {
-  return ArduinoJson::detail::MemoryPool::slotsToBytes(n);
+  using namespace ArduinoJson::detail;
+  return MemoryPool<VariantData>::slotsToBytes(n);
 }
 
 inline size_t sizeofStringBuffer(size_t iteration = 1) {
diff --git a/extras/tests/ResourceManager/StringBuilder.cpp b/extras/tests/ResourceManager/StringBuilder.cpp
index 00905e3d..b649afeb 100644
--- a/extras/tests/ResourceManager/StringBuilder.cpp
+++ b/extras/tests/ResourceManager/StringBuilder.cpp
@@ -2,7 +2,6 @@
 // Copyright © 2014-2024, Benoit BLANCHON
 // MIT License
 
-#include <ArduinoJson/Memory/MemoryPoolImpl.hpp>
 #include <ArduinoJson/Memory/StringBuilder.hpp>
 #include <catch.hpp>
 
diff --git a/extras/tests/ResourceManager/clear.cpp b/extras/tests/ResourceManager/clear.cpp
index a444e69c..a7736039 100644
--- a/extras/tests/ResourceManager/clear.cpp
+++ b/extras/tests/ResourceManager/clear.cpp
@@ -2,7 +2,6 @@
 // Copyright © 2014-2024, Benoit BLANCHON
 // MIT License
 
-#include <ArduinoJson/Memory/MemoryPoolImpl.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Memory/ResourceManagerImpl.hpp>
 #include <ArduinoJson/Strings/StringAdapters.hpp>
diff --git a/extras/tests/ResourceManager/saveString.cpp b/extras/tests/ResourceManager/saveString.cpp
index a054bdef..88c242f6 100644
--- a/extras/tests/ResourceManager/saveString.cpp
+++ b/extras/tests/ResourceManager/saveString.cpp
@@ -2,7 +2,6 @@
 // Copyright © 2014-2024, Benoit BLANCHON
 // MIT License
 
-#include <ArduinoJson/Memory/MemoryPoolImpl.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Strings/StringAdapters.hpp>
 #include <catch.hpp>
diff --git a/extras/tests/ResourceManager/shrinkToFit.cpp b/extras/tests/ResourceManager/shrinkToFit.cpp
index ea2d6527..a09fd8a3 100644
--- a/extras/tests/ResourceManager/shrinkToFit.cpp
+++ b/extras/tests/ResourceManager/shrinkToFit.cpp
@@ -2,7 +2,6 @@
 // Copyright © 2014-2024, Benoit BLANCHON
 // MIT License
 
-#include <ArduinoJson/Memory/MemoryPoolImpl.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Memory/ResourceManagerImpl.hpp>
 #include <catch.hpp>
diff --git a/extras/tests/ResourceManager/size.cpp b/extras/tests/ResourceManager/size.cpp
index e24ecdca..8d4b799d 100644
--- a/extras/tests/ResourceManager/size.cpp
+++ b/extras/tests/ResourceManager/size.cpp
@@ -2,7 +2,6 @@
 // Copyright © 2014-2024, Benoit BLANCHON
 // MIT License
 
-#include <ArduinoJson/Memory/MemoryPoolImpl.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Memory/ResourceManagerImpl.hpp>
 #include <catch.hpp>
diff --git a/extras/tests/ResourceManager/swap.cpp b/extras/tests/ResourceManager/swap.cpp
index 50517d48..a2b1fe99 100644
--- a/extras/tests/ResourceManager/swap.cpp
+++ b/extras/tests/ResourceManager/swap.cpp
@@ -3,7 +3,6 @@
 // MIT License
 
 #include <ArduinoJson/Memory/Alignment.hpp>
-#include <ArduinoJson/Memory/MemoryPoolImpl.hpp>
 #include <ArduinoJson/Memory/ResourceManager.hpp>
 #include <ArduinoJson/Memory/ResourceManagerImpl.hpp>
 #include <catch.hpp>
diff --git a/src/ArduinoJson.hpp b/src/ArduinoJson.hpp
index e61a20d3..a14f2b1a 100644
--- a/src/ArduinoJson.hpp
+++ b/src/ArduinoJson.hpp
@@ -36,13 +36,13 @@
 #include "ArduinoJson/Array/ElementProxy.hpp"
 #include "ArduinoJson/Array/Utilities.hpp"
 #include "ArduinoJson/Collection/CollectionImpl.hpp"
-#include "ArduinoJson/Memory/MemoryPoolImpl.hpp"
 #include "ArduinoJson/Memory/ResourceManagerImpl.hpp"
 #include "ArduinoJson/Object/MemberProxy.hpp"
 #include "ArduinoJson/Object/ObjectImpl.hpp"
 #include "ArduinoJson/Variant/ConverterImpl.hpp"
 #include "ArduinoJson/Variant/JsonVariantCopier.hpp"
 #include "ArduinoJson/Variant/VariantCompare.hpp"
+#include "ArduinoJson/Variant/VariantImpl.hpp"
 #include "ArduinoJson/Variant/VariantRefBaseImpl.hpp"
 
 #include "ArduinoJson/Json/JsonDeserializer.hpp"
diff --git a/src/ArduinoJson/Collection/CollectionData.hpp b/src/ArduinoJson/Collection/CollectionData.hpp
index 616ed18b..a1c575c7 100644
--- a/src/ArduinoJson/Collection/CollectionData.hpp
+++ b/src/ArduinoJson/Collection/CollectionData.hpp
@@ -4,7 +4,7 @@
 
 #pragma once
 
-#include <ArduinoJson/Memory/ResourceManager.hpp>
+#include <ArduinoJson/Memory/MemoryPool.hpp>
 #include <ArduinoJson/Namespace.hpp>
 #include <ArduinoJson/Polyfills/assert.hpp>
 
@@ -13,6 +13,7 @@
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 class VariantData;
+class ResourceManager;
 
 class CollectionIterator {
   friend class CollectionData;
@@ -78,9 +79,7 @@ class CollectionData {
 
   using iterator = CollectionIterator;
 
-  iterator createIterator(const ResourceManager* resources) const {
-    return iterator(resources->getVariant(head_), head_);
-  }
+  iterator createIterator(const ResourceManager* resources) const;
 
   size_t size(const ResourceManager*) const;
   size_t nesting(const ResourceManager*) const;
@@ -98,15 +97,17 @@ class CollectionData {
   }
 
  protected:
-  void appendOne(VariantWithId slot, const ResourceManager* resources);
-  void appendPair(VariantWithId key, VariantWithId value,
+  void appendOne(SlotWithId<VariantData> slot,
+                 const ResourceManager* resources);
+  void appendPair(SlotWithId<VariantData> key, SlotWithId<VariantData> value,
                   const ResourceManager* resources);
 
   void removeOne(iterator it, ResourceManager* resources);
   void removePair(iterator it, ResourceManager* resources);
 
  private:
-  VariantWithId getPreviousSlot(VariantData*, const ResourceManager*) const;
+  SlotWithId<VariantData> getPreviousSlot(VariantData*,
+                                          const ResourceManager*) const;
 };
 
 inline const VariantData* collectionToVariant(
diff --git a/src/ArduinoJson/Collection/CollectionImpl.hpp b/src/ArduinoJson/Collection/CollectionImpl.hpp
index d68f48ac..4c022b9c 100644
--- a/src/ArduinoJson/Collection/CollectionImpl.hpp
+++ b/src/ArduinoJson/Collection/CollectionImpl.hpp
@@ -25,7 +25,12 @@ inline void CollectionIterator::next(const ResourceManager* resources) {
     nextId_ = slot_->next();
 }
 
-inline void CollectionData::appendOne(VariantWithId slot,
+inline CollectionData::iterator CollectionData::createIterator(
+    const ResourceManager* resources) const {
+  return iterator(resources->getVariant(head_), head_);
+}
+
+inline void CollectionData::appendOne(SlotWithId<VariantData> slot,
                                       const ResourceManager* resources) {
   if (tail_ != NULL_SLOT) {
     auto tail = resources->getVariant(tail_);
@@ -37,7 +42,8 @@ inline void CollectionData::appendOne(VariantWithId slot,
   }
 }
 
-inline void CollectionData::appendPair(VariantWithId key, VariantWithId value,
+inline void CollectionData::appendPair(SlotWithId<VariantData> key,
+                                       SlotWithId<VariantData> value,
                                        const ResourceManager* resources) {
   key->setNext(value.id());
 
@@ -57,22 +63,22 @@ inline void CollectionData::clear(ResourceManager* resources) {
     auto currId = next;
     auto slot = resources->getVariant(next);
     next = slot->next();
-    resources->freeVariant(VariantWithId(slot, currId));
+    resources->freeVariant(SlotWithId<VariantData>(slot, currId));
   }
 
   head_ = NULL_SLOT;
   tail_ = NULL_SLOT;
 }
 
-inline VariantWithId CollectionData::getPreviousSlot(
+inline SlotWithId<VariantData> CollectionData::getPreviousSlot(
     VariantData* target, const ResourceManager* resources) const {
-  auto prev = VariantWithId();
+  auto prev = SlotWithId<VariantData>();
   auto currentId = head_;
   while (currentId != NULL_SLOT) {
     auto currentSlot = resources->getVariant(currentId);
     if (currentSlot == target)
       break;
-    prev = VariantWithId(currentSlot, currentId);
+    prev = SlotWithId<VariantData>(currentSlot, currentId);
     currentId = currentSlot->next();
   }
   return prev;
diff --git a/src/ArduinoJson/Memory/MemoryPool.hpp b/src/ArduinoJson/Memory/MemoryPool.hpp
index d7062b3a..742e9d7b 100644
--- a/src/ArduinoJson/Memory/MemoryPool.hpp
+++ b/src/ArduinoJson/Memory/MemoryPool.hpp
@@ -10,15 +10,15 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class VariantData;
 using SlotId = uint_t<ARDUINOJSON_SLOT_ID_SIZE * 8>;
 using SlotCount = SlotId;
 const SlotId NULL_SLOT = SlotId(-1);
 
+template <typename T>
 class SlotWithId {
  public:
   SlotWithId() : slot_(nullptr), id_(NULL_SLOT) {}
-  SlotWithId(VariantData* slot, SlotId id) : slot_(slot), id_(id) {
+  SlotWithId(T* slot, SlotId id) : slot_(slot), id_(id) {
     ARDUINOJSON_ASSERT((slot == nullptr) == (id == NULL_SLOT));
   }
 
@@ -30,38 +30,81 @@ class SlotWithId {
     return id_;
   }
 
-  VariantData* ptr() const {
+  T* ptr() const {
     return slot_;
   }
 
-  VariantData* operator->() {
+  T* operator->() const {
     ARDUINOJSON_ASSERT(slot_ != nullptr);
     return slot_;
   }
 
  private:
-  VariantData* slot_;
+  T* slot_;
   SlotId id_;
 };
 
+template <typename T>
 class MemoryPool {
  public:
-  void create(SlotCount cap, Allocator* allocator);
-  void destroy(Allocator* allocator);
+  void create(SlotCount cap, Allocator* allocator) {
+    ARDUINOJSON_ASSERT(cap > 0);
+    slots_ = reinterpret_cast<T*>(allocator->allocate(slotsToBytes(cap)));
+    capacity_ = slots_ ? cap : 0;
+    usage_ = 0;
+  }
 
-  SlotWithId allocSlot();
-  VariantData* getSlot(SlotId id) const;
-  void clear();
-  void shrinkToFit(Allocator*);
-  SlotCount usage() const;
+  void destroy(Allocator* allocator) {
+    if (slots_)
+      allocator->deallocate(slots_);
+    slots_ = nullptr;
+    capacity_ = 0;
+    usage_ = 0;
+  }
 
-  static SlotCount bytesToSlots(size_t);
-  static size_t slotsToBytes(SlotCount);
+  SlotWithId<T> allocSlot() {
+    if (!slots_)
+      return {};
+    if (usage_ >= capacity_)
+      return {};
+    auto index = usage_++;
+    return {slots_ + index, SlotId(index)};
+  }
+
+  T* getSlot(SlotId id) const {
+    ARDUINOJSON_ASSERT(id < usage_);
+    return slots_ + id;
+  }
+
+  void clear() {
+    usage_ = 0;
+  }
+
+  void shrinkToFit(Allocator* allocator) {
+    auto newSlots = reinterpret_cast<T*>(
+        allocator->reallocate(slots_, slotsToBytes(usage_)));
+    if (newSlots) {
+      slots_ = newSlots;
+      capacity_ = usage_;
+    }
+  }
+
+  SlotCount usage() const {
+    return usage_;
+  }
+
+  static SlotCount bytesToSlots(size_t n) {
+    return static_cast<SlotCount>(n / sizeof(T));
+  }
+
+  static size_t slotsToBytes(SlotCount n) {
+    return n * sizeof(T);
+  }
 
  private:
   SlotCount capacity_;
   SlotCount usage_;
-  VariantData* slots_;
+  T* slots_;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Memory/MemoryPoolImpl.hpp b/src/ArduinoJson/Memory/MemoryPoolImpl.hpp
deleted file mode 100644
index 059ef788..00000000
--- a/src/ArduinoJson/Memory/MemoryPoolImpl.hpp
+++ /dev/null
@@ -1,81 +0,0 @@
-// ArduinoJson - https://arduinojson.org
-// Copyright © 2014-2024, Benoit BLANCHON
-// MIT License
-
-#pragma once
-
-#include <ArduinoJson/Memory/MemoryPool.hpp>
-#include <ArduinoJson/Variant/VariantData.hpp>
-
-ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
-
-inline void MemoryPool::create(SlotCount cap, Allocator* allocator) {
-  ARDUINOJSON_ASSERT(cap > 0);
-  slots_ =
-      reinterpret_cast<VariantData*>(allocator->allocate(slotsToBytes(cap)));
-  capacity_ = slots_ ? cap : 0;
-  usage_ = 0;
-}
-
-inline void MemoryPool::destroy(Allocator* allocator) {
-  if (slots_)
-    allocator->deallocate(slots_);
-  slots_ = nullptr;
-  capacity_ = 0;
-  usage_ = 0;
-}
-
-inline void MemoryPool::shrinkToFit(Allocator* allocator) {
-  auto newSlots = reinterpret_cast<VariantData*>(
-      allocator->reallocate(slots_, slotsToBytes(usage_)));
-  if (newSlots) {
-    slots_ = newSlots;
-    capacity_ = usage_;
-  }
-}
-
-inline SlotWithId MemoryPool::allocSlot() {
-  if (!slots_)
-    return {};
-  if (usage_ >= capacity_)
-    return {};
-  auto index = usage_++;
-  auto slot = &slots_[index];
-  return {slot, SlotId(index)};
-}
-
-inline VariantData* MemoryPool::getSlot(SlotId id) const {
-  ARDUINOJSON_ASSERT(id < usage_);
-  return &slots_[id];
-}
-
-inline SlotCount MemoryPool::usage() const {
-  return usage_;
-}
-
-inline void MemoryPool::clear() {
-  usage_ = 0;
-}
-
-inline SlotCount MemoryPool::bytesToSlots(size_t n) {
-  return static_cast<SlotCount>(n / sizeof(VariantData));
-}
-
-inline size_t MemoryPool::slotsToBytes(SlotCount n) {
-  return n * sizeof(VariantData);
-}
-
-inline SlotWithId MemoryPoolList::allocFromFreeList() {
-  ARDUINOJSON_ASSERT(freeList_ != NULL_SLOT);
-  auto id = freeList_;
-  auto slot = getSlot(freeList_);
-  freeList_ = reinterpret_cast<FreeSlot*>(slot)->next;
-  return {slot, id};
-}
-
-inline void MemoryPoolList::freeSlot(SlotWithId slot) {
-  reinterpret_cast<FreeSlot*>(slot.ptr())->next = freeList_;
-  freeList_ = slot.id();
-}
-
-ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Memory/MemoryPoolList.hpp b/src/ArduinoJson/Memory/MemoryPoolList.hpp
index 27fe57c4..0aea4992 100644
--- a/src/ArduinoJson/Memory/MemoryPoolList.hpp
+++ b/src/ArduinoJson/Memory/MemoryPoolList.hpp
@@ -14,12 +14,17 @@ ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
 using PoolCount = SlotId;
 
+template <typename T>
 class MemoryPoolList {
   struct FreeSlot {
     SlotId next;
   };
 
+  static_assert(sizeof(FreeSlot) <= sizeof(T), "T is too small");
+
  public:
+  using Pool = MemoryPool<T>;
+
   MemoryPoolList() = default;
 
   ~MemoryPoolList() {
@@ -74,7 +79,7 @@ class MemoryPoolList {
     return *this;
   }
 
-  SlotWithId allocSlot(Allocator* allocator) {
+  SlotWithId<T> allocSlot(Allocator* allocator) {
     // try to allocate from free list
     if (freeList_ != NULL_SLOT) {
       return allocFromFreeList();
@@ -95,9 +100,12 @@ class MemoryPoolList {
     return allocFromLastPool();
   }
 
-  void freeSlot(SlotWithId slot);
+  void freeSlot(SlotWithId<T> slot) {
+    reinterpret_cast<FreeSlot*>(slot.ptr())->next = freeList_;
+    freeList_ = slot.id();
+  }
 
-  VariantData* getSlot(SlotId id) const {
+  T* getSlot(SlotId id) const {
     if (id == NULL_SLOT)
       return nullptr;
     auto poolIndex = SlotId(id / ARDUINOJSON_POOL_CAPACITY);
@@ -125,21 +133,31 @@ class MemoryPoolList {
     return total;
   }
 
+  size_t size() const {
+    return Pool::slotsToBytes(usage());
+  }
+
   void shrinkToFit(Allocator* allocator) {
     if (count_ > 0)
       pools_[count_ - 1].shrinkToFit(allocator);
     if (pools_ != preallocatedPools_ && count_ != capacity_) {
-      pools_ = static_cast<MemoryPool*>(
-          allocator->reallocate(pools_, count_ * sizeof(MemoryPool)));
+      pools_ = static_cast<Pool*>(
+          allocator->reallocate(pools_, count_ * sizeof(Pool)));
       ARDUINOJSON_ASSERT(pools_ != nullptr);  // realloc to smaller can't fail
       capacity_ = count_;
     }
   }
 
  private:
-  SlotWithId allocFromFreeList();
+  SlotWithId<T> allocFromFreeList() {
+    ARDUINOJSON_ASSERT(freeList_ != NULL_SLOT);
+    auto id = freeList_;
+    auto slot = getSlot(freeList_);
+    freeList_ = reinterpret_cast<FreeSlot*>(slot)->next;
+    return {slot, id};
+  }
 
-  SlotWithId allocFromLastPool() {
+  SlotWithId<T> allocFromLastPool() {
     ARDUINOJSON_ASSERT(count_ > 0);
     auto poolIndex = SlotId(count_ - 1);
     auto slot = pools_[poolIndex].allocSlot();
@@ -149,7 +167,7 @@ class MemoryPoolList {
             SlotId(poolIndex * ARDUINOJSON_POOL_CAPACITY + slot.id())};
   }
 
-  MemoryPool* addPool(Allocator* allocator) {
+  Pool* addPool(Allocator* allocator) {
     if (count_ == capacity_ && !increaseCapacity(allocator))
       return nullptr;
     auto pool = &pools_[count_++];
@@ -167,24 +185,23 @@ class MemoryPoolList {
     auto newCapacity = PoolCount(capacity_ * 2);
 
     if (pools_ == preallocatedPools_) {
-      newPools = allocator->allocate(newCapacity * sizeof(MemoryPool));
+      newPools = allocator->allocate(newCapacity * sizeof(Pool));
       if (!newPools)
         return false;
       memcpy(newPools, preallocatedPools_, sizeof(preallocatedPools_));
     } else {
-      newPools =
-          allocator->reallocate(pools_, newCapacity * sizeof(MemoryPool));
+      newPools = allocator->reallocate(pools_, newCapacity * sizeof(Pool));
       if (!newPools)
         return false;
     }
 
-    pools_ = static_cast<MemoryPool*>(newPools);
+    pools_ = static_cast<Pool*>(newPools);
     capacity_ = newCapacity;
     return true;
   }
 
-  MemoryPool preallocatedPools_[ARDUINOJSON_INITIAL_POOL_COUNT];
-  MemoryPool* pools_ = preallocatedPools_;
+  Pool preallocatedPools_[ARDUINOJSON_INITIAL_POOL_COUNT];
+  Pool* pools_ = preallocatedPools_;
   PoolCount count_ = 0;
   PoolCount capacity_ = ARDUINOJSON_INITIAL_POOL_COUNT;
   SlotId freeList_ = NULL_SLOT;
diff --git a/src/ArduinoJson/Memory/ResourceManager.hpp b/src/ArduinoJson/Memory/ResourceManager.hpp
index 45e329cd..7b23923e 100644
--- a/src/ArduinoJson/Memory/ResourceManager.hpp
+++ b/src/ArduinoJson/Memory/ResourceManager.hpp
@@ -10,10 +10,10 @@
 #include <ArduinoJson/Polyfills/assert.hpp>
 #include <ArduinoJson/Polyfills/utility.hpp>
 #include <ArduinoJson/Strings/StringAdapters.hpp>
+#include <ArduinoJson/Variant/VariantData.hpp>
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class MemoryPool;
 class VariantData;
 class VariantWithId;
 
@@ -42,16 +42,16 @@ class ResourceManager {
   }
 
   size_t size() const {
-    return MemoryPool::slotsToBytes(variantPools_.usage()) + stringPool_.size();
+    return variantPools_.size() + stringPool_.size();
   }
 
   bool overflowed() const {
     return overflowed_;
   }
 
-  VariantWithId allocVariant();
+  SlotWithId<VariantData> allocVariant();
 
-  void freeVariant(VariantWithId slot);
+  void freeVariant(SlotWithId<VariantData> slot);
 
   VariantData* getVariant(SlotId id) const;
 
@@ -112,7 +112,7 @@ class ResourceManager {
   Allocator* allocator_;
   bool overflowed_;
   StringPool stringPool_;
-  MemoryPoolList variantPools_;
+  MemoryPoolList<VariantData> variantPools_;
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Memory/ResourceManagerImpl.hpp b/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
index 0deb5729..73200f45 100644
--- a/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
+++ b/src/ArduinoJson/Memory/ResourceManagerImpl.hpp
@@ -10,7 +10,7 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-inline VariantWithId ResourceManager::allocVariant() {
+inline SlotWithId<VariantData> ResourceManager::allocVariant() {
   auto p = variantPools_.allocSlot(allocator_);
   if (!p) {
     overflowed_ = true;
@@ -19,7 +19,7 @@ inline VariantWithId ResourceManager::allocVariant() {
   return {new (p.ptr()) VariantData, p.id()};
 }
 
-inline void ResourceManager::freeVariant(VariantWithId variant) {
+inline void ResourceManager::freeVariant(SlotWithId<VariantData> variant) {
   variant->setNull(this);
   variantPools_.freeSlot(variant);
 }
diff --git a/src/ArduinoJson/Memory/StringPool.hpp b/src/ArduinoJson/Memory/StringPool.hpp
index 91851e80..6121b290 100644
--- a/src/ArduinoJson/Memory/StringPool.hpp
+++ b/src/ArduinoJson/Memory/StringPool.hpp
@@ -12,8 +12,6 @@
 
 ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
 
-class MemoryPool;
-
 class StringPool {
  public:
   StringPool() = default;
diff --git a/src/ArduinoJson/Variant/VariantData.hpp b/src/ArduinoJson/Variant/VariantData.hpp
index f36fcaf0..86b2adce 100644
--- a/src/ArduinoJson/Variant/VariantData.hpp
+++ b/src/ArduinoJson/Variant/VariantData.hpp
@@ -408,14 +408,7 @@ class VariantData {
   }
 
   template <typename T>
-  void setRawString(SerializedValue<T> value, ResourceManager* resources) {
-    release(resources);
-    auto dup = resources->saveString(adaptString(value.data(), value.size()));
-    if (dup)
-      setRawString(dup);
-    else
-      setNull();
-  }
+  void setRawString(SerializedValue<T> value, ResourceManager* resources);
 
   template <typename T>
   static void setRawString(VariantData* var, SerializedValue<T> value,
@@ -426,25 +419,7 @@ class VariantData {
   }
 
   template <typename TAdaptedString>
-  bool setString(TAdaptedString value, ResourceManager* resources) {
-    setNull(resources);
-
-    if (value.isNull())
-      return false;
-
-    if (value.isLinked()) {
-      setLinkedString(value.data());
-      return true;
-    }
-
-    auto dup = resources->saveString(value);
-    if (dup) {
-      setOwnedString(dup);
-      return true;
-    }
-
-    return false;
-  }
+  bool setString(TAdaptedString value, ResourceManager* resources);
 
   bool setString(StringNode* s, ResourceManager*) {
     setOwnedString(s);
@@ -524,30 +499,7 @@ class VariantData {
   }
 
  private:
-  void release(ResourceManager* resources) {
-    if (type_ & OWNED_VALUE_BIT)
-      resources->dereferenceString(content_.asOwnedString->data);
-
-    auto collection = asCollection();
-    if (collection)
-      collection->clear(resources);
-  }
-};
-
-class VariantWithId : public SlotWithId {
- public:
-  VariantWithId() {}
-  VariantWithId(VariantData* data, SlotId id)
-      : SlotWithId(reinterpret_cast<VariantData*>(data), id) {}
-
-  VariantData* ptr() {
-    return reinterpret_cast<VariantData*>(SlotWithId::ptr());
-  }
-
-  VariantData* operator->() {
-    ARDUINOJSON_ASSERT(ptr() != nullptr);
-    return ptr();
-  }
+  void release(ResourceManager* resources);
 };
 
 ARDUINOJSON_END_PRIVATE_NAMESPACE
diff --git a/src/ArduinoJson/Variant/VariantImpl.hpp b/src/ArduinoJson/Variant/VariantImpl.hpp
new file mode 100644
index 00000000..ae131509
--- /dev/null
+++ b/src/ArduinoJson/Variant/VariantImpl.hpp
@@ -0,0 +1,54 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2024, Benoit BLANCHON
+// MIT License
+
+#pragma once
+
+#include <ArduinoJson/Memory/ResourceManager.hpp>
+#include <ArduinoJson/Variant/VariantData.hpp>
+
+ARDUINOJSON_BEGIN_PRIVATE_NAMESPACE
+
+template <typename T>
+inline void VariantData::setRawString(SerializedValue<T> value,
+                                      ResourceManager* resources) {
+  release(resources);
+  auto dup = resources->saveString(adaptString(value.data(), value.size()));
+  if (dup)
+    setRawString(dup);
+  else
+    setNull();
+}
+
+template <typename TAdaptedString>
+inline bool VariantData::setString(TAdaptedString value,
+                                   ResourceManager* resources) {
+  setNull(resources);
+
+  if (value.isNull())
+    return false;
+
+  if (value.isLinked()) {
+    setLinkedString(value.data());
+    return true;
+  }
+
+  auto dup = resources->saveString(value);
+  if (dup) {
+    setOwnedString(dup);
+    return true;
+  }
+
+  return false;
+}
+
+inline void VariantData::release(ResourceManager* resources) {
+  if (type_ & OWNED_VALUE_BIT)
+    resources->dereferenceString(content_.asOwnedString->data);
+
+  auto collection = asCollection();
+  if (collection)
+    collection->clear(resources);
+}
+
+ARDUINOJSON_END_PRIVATE_NAMESPACE