diff --git a/Libraries/SPTarkov.Server.Core/Controllers/InsuranceController.cs b/Libraries/SPTarkov.Server.Core/Controllers/InsuranceController.cs
index b8b144f8..204e7247 100644
--- a/Libraries/SPTarkov.Server.Core/Controllers/InsuranceController.cs
+++ b/Libraries/SPTarkov.Server.Core/Controllers/InsuranceController.cs
@@ -244,7 +244,7 @@ public class InsuranceController(
     protected Dictionary<string, List<Item>> PopulateParentAttachmentsMap(
         string rootItemParentID,
         Insurance insured,
-        Dictionary<string, Item> itemsMap
+        Dictionary<MongoId, Item> itemsMap
     )
     {
         var mainParentToAttachmentsMap = new Dictionary<string, List<Item>>();
@@ -340,7 +340,7 @@ public class InsuranceController(
     /// <returns></returns>
     protected Dictionary<string, List<Item>> RemoveNonModdableAttachments(
         Dictionary<string, List<Item>> parentAttachmentsMap,
-        Dictionary<string, Item> itemsMap
+        Dictionary<MongoId, Item> itemsMap
     )
     {
         var updatedMap = new Dictionary<string, List<Item>>();
@@ -442,7 +442,7 @@ public class InsuranceController(
     /// <param name="toDelete">Tracked attachment ids to be removed</param>
     protected void ProcessAttachments(
         Dictionary<string, List<Item>> mainParentToAttachmentsMap,
-        Dictionary<string, Item> itemsMap,
+        Dictionary<MongoId, Item> itemsMap,
         string? insuredTraderId,
         HashSet<string> toDelete
     )
diff --git a/Libraries/SPTarkov.Server.Core/Controllers/RagfairController.cs b/Libraries/SPTarkov.Server.Core/Controllers/RagfairController.cs
index f52d0dc7..01132526 100644
--- a/Libraries/SPTarkov.Server.Core/Controllers/RagfairController.cs
+++ b/Libraries/SPTarkov.Server.Core/Controllers/RagfairController.cs
@@ -324,7 +324,7 @@ public class RagfairController
     /// <param name="searchRequest">Client search request data</param>
     /// <param name="offers">Ragfair offers to get categories for</param>
     /// <returns>Record with templates + counts</returns>
-    protected Dictionary<string, int> GetSpecificCategories(
+    protected Dictionary<MongoId, int> GetSpecificCategories(
         PmcData pmcProfile,
         SearchRequestData searchRequest,
         List<RagfairOffer> offers
@@ -352,7 +352,7 @@ public class RagfairController
                 _logger.Debug(_jsonUtil.Serialize(searchRequest));
             }
 
-            return new Dictionary<string, int>();
+            return [];
         }
 
         return _ragfairServer.GetAllActiveCategories(
diff --git a/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs b/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs
index 18c42444..be57b0c0 100644
--- a/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs
+++ b/Libraries/SPTarkov.Server.Core/Extensions/ItemExtensions.cs
@@ -1,4 +1,5 @@
-using SPTarkov.Server.Core.Models.Eft.Common.Tables;
+using SPTarkov.Server.Core.Models.Common;
+using SPTarkov.Server.Core.Models.Eft.Common.Tables;
 
 namespace SPTarkov.Server.Core.Extensions
 {
@@ -119,9 +120,7 @@ namespace SPTarkov.Server.Core.Extensions
         )
         {
             // Get items parent
-            var parent = items.FirstOrDefault(item =>
-                item.Id.Equals(itemToCheck.ParentId, StringComparison.OrdinalIgnoreCase)
-            );
+            var parent = items.FirstOrDefault(item => item.Id.Equals(itemToCheck.ParentId));
             if (parent is null)
             // No parent, end of line, not inside container
             {
@@ -156,7 +155,7 @@ namespace SPTarkov.Server.Core.Extensions
         /// </summary>
         /// <param name="items">Collection of items</param>
         /// <returns>Dictionary of items</returns>
-        public static Dictionary<string, Item> GenerateItemsMap(this IEnumerable<Item> items)
+        public static Dictionary<MongoId, Item> GenerateItemsMap(this IEnumerable<Item> items)
         {
             // Convert list to dictionary, keyed by items Id
             return items.ToDictionary(item => item.Id);
@@ -175,9 +174,7 @@ namespace SPTarkov.Server.Core.Extensions
             foreach (var item in items)
             {
                 // Check if the item's parent exists.
-                var parentExists = items.Any(parentItem =>
-                    parentItem.Id.Equals(item.ParentId, StringComparison.OrdinalIgnoreCase)
-                );
+                var parentExists = items.Any(parentItem => parentItem.Id.Equals(item.ParentId));
 
                 // If the parent does not exist and the item is not already a 'hideout' item, adopt the orphaned item by
                 // setting the parent ID to the PMCs inventory equipment ID, the slot ID to 'hideout', and remove the location.
diff --git a/Libraries/SPTarkov.Server.Core/Generators/LocationLootGenerator.cs b/Libraries/SPTarkov.Server.Core/Generators/LocationLootGenerator.cs
index 1752fe67..aa60da68 100644
--- a/Libraries/SPTarkov.Server.Core/Generators/LocationLootGenerator.cs
+++ b/Libraries/SPTarkov.Server.Core/Generators/LocationLootGenerator.cs
@@ -2,6 +2,7 @@ using System.Text.Json.Serialization;
 using SPTarkov.DI.Annotations;
 using SPTarkov.Server.Core.Extensions;
 using SPTarkov.Server.Core.Helpers;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Eft.Common;
 using SPTarkov.Server.Core.Models.Eft.Common.Tables;
 using SPTarkov.Server.Core.Models.Enums;
@@ -1084,8 +1085,9 @@ public class LocationLootGenerator(
     )
     {
         var chosenItem = items.FirstOrDefault(item => item.Id == chosenComposedKey);
-        var chosenTpl = chosenItem?.Template;
-        if (chosenTpl is null)
+        MongoId chosenTpl = chosenItem?.Template ?? MongoId.Empty();
+
+        if (chosenTpl == null)
         {
             throw new Exception(
                 $"Item for tpl {chosenComposedKey} was not found in the spawn point"
diff --git a/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs b/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs
index acc60e67..b1e0ab51 100644
--- a/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs
+++ b/Libraries/SPTarkov.Server.Core/Helpers/ItemHelper.cs
@@ -1,6 +1,7 @@
 using System.Collections.Frozen;
 using SPTarkov.DI.Annotations;
 using SPTarkov.Server.Core.Extensions;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Eft.Common;
 using SPTarkov.Server.Core.Models.Eft.Common.Tables;
 using SPTarkov.Server.Core.Models.Enums;
@@ -144,9 +145,7 @@ public class ItemHelper(
             );
 
         // Check if any item in the filtered pool matches the provided item
-        return filteredPool.FirstOrDefault(poolItem =>
-            poolItem.Template.Equals(tpl, StringComparison.OrdinalIgnoreCase)
-        );
+        return filteredPool.FirstOrDefault(poolItem => poolItem.Template.Equals(tpl));
     }
 
     /// <summary>
@@ -171,9 +170,7 @@ public class ItemHelper(
 
         foreach (var itemOf1 in item1)
         {
-            var itemOf2 = item2.FirstOrDefault(i2 =>
-                i2.Template.Equals(itemOf1.Template, StringComparison.OrdinalIgnoreCase)
-            );
+            var itemOf2 = item2.FirstOrDefault(i2 => i2.Template.Equals(itemOf1.Template));
             if (itemOf2 is null)
             {
                 return false;
@@ -327,6 +324,24 @@ public class ItemHelper(
         return _itemBaseClassService.ItemHasBaseClass(tpl, baseClassTpls);
     }
 
+    /// <summary>
+    /// Temporary until we have better MongoId handling
+    /// </summary>
+    /// <param name="tpl"></param>
+    /// <param name="baseClassTpls"></param>
+    /// <returns></returns>
+    public bool IsOfBaseclasses(string tpl, ICollection<MongoId> baseClassTpls)
+    {
+        List<string> MongoList = [];
+
+        foreach (var baseTpl in baseClassTpls)
+        {
+            MongoList.Add(baseTpl);
+        }
+
+        return _itemBaseClassService.ItemHasBaseClass(tpl, MongoList);
+    }
+
     /// <summary>
     /// Does the provided item have the chance to require soft armor inserts
     /// Only applies to helmets/vest/armors
@@ -428,7 +443,7 @@ public class ItemHelper(
     /// </summary>
     /// <param name="tpls">item tpls to look up the price of</param>
     /// <returns>Total price in roubles</returns>
-    public double GetItemAndChildrenPrice(IEnumerable<string> tpls)
+    public double GetItemAndChildrenPrice(IEnumerable<MongoId> tpls)
     {
         // Run getItemPrice for each tpl in tpls array, return sum
         return tpls.Aggregate(
@@ -910,9 +925,7 @@ public class ItemHelper(
         {
             var filterResult = itemsToSearch.Where(item =>
             {
-                return by == "tpl"
-                    ? item.Template.Equals(barterId, StringComparison.OrdinalIgnoreCase)
-                    : item.Id.Equals(barterId, StringComparison.OrdinalIgnoreCase);
+                return by == "tpl" ? item.Template.Equals(barterId) : item.Id.Equals(barterId);
             });
 
             matchingItems.AddRange(filterResult);
@@ -1266,7 +1279,7 @@ public class ItemHelper(
     /// <param name="itemId">The unique identifier of the item for which to find the main parent.</param>
     /// <param name="itemsMap">A Dictionary containing item IDs mapped to their corresponding Item objects for quick lookup.</param>
     /// <returns>The Item object representing the top-most parent of the given item, or null if no such parent exists.</returns>
-    public Item? GetAttachmentMainParent(string itemId, Dictionary<string, Item> itemsMap)
+    public Item? GetAttachmentMainParent(string itemId, Dictionary<MongoId, Item> itemsMap)
     {
         var currentItem = itemsMap.FirstOrDefault(x => x.Key == itemId).Value;
 
@@ -1337,10 +1350,7 @@ public class ItemHelper(
     public ItemSize GetItemSize(ICollection<Item> items, string rootItemId)
     {
         var rootTemplate = GetItem(
-            items
-                .Where(x => x.Id.Equals(rootItemId, StringComparison.OrdinalIgnoreCase))
-                .ToList()[0]
-                .Template
+            items.Where(x => x.Id.Equals(rootItemId)).ToList()[0].Template
         ).Value;
         var width = rootTemplate.Properties.Width;
         var height = rootTemplate.Properties.Height;
@@ -1432,11 +1442,7 @@ public class ItemHelper(
         var cartridgeMaxStackSize = cartridgeDetails.Value.Properties.StackMaxSize;
 
         // Exit early if ammo already exists in box
-        if (
-            ammoBox.Any(item =>
-                item.Template.Equals(cartridgeTpl, StringComparison.OrdinalIgnoreCase)
-            )
-        )
+        if (ammoBox.Any(item => item.Template.Equals(cartridgeTpl)))
         {
             return;
         }
@@ -1931,7 +1937,7 @@ public class ItemHelper(
 
             // Has parentId + no remapping exists for its parent
             if (
-                mod.ParentId is not null
+                mod.ParentId != null
                 && (!idMappings.ContainsKey(mod.ParentId) || idMappings?[mod.ParentId] is null)
             )
             // Make remapping for items parentId
@@ -1940,7 +1946,7 @@ public class ItemHelper(
             }
 
             mod.Id = idMappings[mod.Id];
-            if (mod.ParentId is not null)
+            if (mod.ParentId != null)
             {
                 mod.ParentId = idMappings[mod.ParentId];
             }
@@ -1973,7 +1979,7 @@ public class ItemHelper(
         foreach (var item in itemWithChildren)
         {
             // Root, update id
-            if (item.Id.Equals(rootItemExistingId, StringComparison.OrdinalIgnoreCase))
+            if (item.Id.Equals(rootItemExistingId))
             {
                 item.Id = newId;
 
diff --git a/Libraries/SPTarkov.Server.Core/Helpers/PresetHelper.cs b/Libraries/SPTarkov.Server.Core/Helpers/PresetHelper.cs
index b3fd6287..3603799f 100644
--- a/Libraries/SPTarkov.Server.Core/Helpers/PresetHelper.cs
+++ b/Libraries/SPTarkov.Server.Core/Helpers/PresetHelper.cs
@@ -1,4 +1,5 @@
 using SPTarkov.DI.Annotations;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Eft.Common;
 using SPTarkov.Server.Core.Models.Enums;
 using SPTarkov.Server.Core.Models.Spt.Presets;
@@ -39,7 +40,7 @@ public class PresetHelper(DatabaseService _databaseService, ItemHelper _itemHelp
     /// Get weapon and armor default presets, keyed to root items tpl
     /// </summary>
     /// <returns>dictionary of presets keyed by the root items tpl</returns>
-    public Dictionary<string, Preset> GetDefaultPresetsByTplKey()
+    public Dictionary<MongoId, Preset> GetDefaultPresetsByTplKey()
     {
         // Weapons and equipment keyed by their preset id
         var weapons = GetDefaultWeaponPresets().Values;
diff --git a/Libraries/SPTarkov.Server.Core/Models/Common/MongoId.cs b/Libraries/SPTarkov.Server.Core/Models/Common/MongoId.cs
index f8cbdb3a..313e2514 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Common/MongoId.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Common/MongoId.cs
@@ -126,7 +126,17 @@ public readonly partial struct MongoId : IEquatable<MongoId>
         return _stringId.GetHashCode();
     }
 
-    public MongoId Empty()
+    public bool IsEmpty()
+    {
+        if (_stringId == "000000000000000000000000")
+        {
+            return true;
+        }
+
+        return false;
+    }
+
+    public static MongoId Empty()
     {
         return new MongoId("000000000000000000000000");
     }
diff --git a/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Item.cs b/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Item.cs
index a57ad2b3..86e3837a 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Item.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Item.cs
@@ -1,4 +1,5 @@
 using System.Text.Json.Serialization;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Enums;
 using SPTarkov.Server.Core.Utils.Json.Converters;
 
@@ -9,29 +10,17 @@ public record Item
     [JsonExtensionData]
     public Dictionary<string, object>? ExtensionData { get; set; }
 
-    private string? _id;
-
     private string? _parentId;
 
     private string? _SlotId;
 
-    private string? _tpl;
-
     // MongoId
     [JsonPropertyName("_id")]
-    public string? Id
-    {
-        get { return _id; }
-        set { _id = string.Intern(value); }
-    }
+    public required MongoId Id { get; set; }
 
     [JsonPropertyName("_tpl")]
     // MongoId
-    public string? Template
-    {
-        get { return _tpl; }
-        set { _tpl = string.Intern(value); }
-    }
+    public MongoId Template { get; set; }
 
     [JsonPropertyName("parentId")]
     public string? ParentId
@@ -66,7 +55,7 @@ public record HideoutItem
     ///     Hideout inventory id that was used by improvement action
     /// </summary>
     [JsonPropertyName("_id")]
-    public string? _Id
+    public MongoId _Id
     {
         get { return Id; }
         set
@@ -81,10 +70,10 @@ public record HideoutItem
     }
 
     [JsonPropertyName("id")]
-    public string? Id { get; set; }
+    public required MongoId Id { get; set; }
 
     [JsonPropertyName("_tpl")]
-    public string? Template { get; set; }
+    public required MongoId Template { get; set; }
 
     [JsonPropertyName("upd")]
     public Upd? Upd { get; set; }
diff --git a/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Trader.cs b/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Trader.cs
index 565008ee..f1eeebb0 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Trader.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Eft/Common/Tables/Trader.cs
@@ -1,4 +1,5 @@
 using System.Text.Json.Serialization;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Enums;
 using SPTarkov.Server.Core.Models.Spt.Services;
 using SPTarkov.Server.Core.Utils.Json.Converters;
@@ -38,7 +39,7 @@ public record TraderBase
     public bool? RefreshTraderRagfairOffers { get; set; }
 
     [JsonPropertyName("_id")]
-    public string? Id { get; set; }
+    public MongoId Id { get; set; }
 
     [JsonPropertyName("availableInRaid")]
     public bool? AvailableInRaid { get; set; }
@@ -137,11 +138,11 @@ public record ItemBuyData
 
     // MongoId
     [JsonPropertyName("category")]
-    public List<string>? Category { get; set; }
+    public required List<MongoId> Category { get; set; }
 
     // MongoId
     [JsonPropertyName("id_list")]
-    public List<string>? IdList { get; set; }
+    public required List<MongoId> IdList { get; set; }
 }
 
 public record ItemSellData
@@ -150,10 +151,10 @@ public record ItemSellData
     public Dictionary<string, object>? ExtensionData { get; set; }
 
     [JsonPropertyName("category")]
-    public required List<string> Category { get; set; }
+    public required List<MongoId> Category { get; set; }
 
     [JsonPropertyName("id_list")]
-    public required List<string> IdList { get; set; }
+    public required List<MongoId> IdList { get; set; }
 }
 
 public record TraderInsurance
@@ -166,7 +167,7 @@ public record TraderInsurance
 
     // MongoId
     [JsonPropertyName("excluded_category")]
-    public List<string>? ExcludedCategory { get; set; }
+    public List<MongoId>? ExcludedCategory { get; set; }
 
     // Confirmed in client
     [JsonPropertyName("max_return_hour")]
@@ -225,7 +226,7 @@ public record TraderRepair
     public bool? Availability { get; set; }
 
     [JsonPropertyName("currency")]
-    public string? Currency { get; set; }
+    public MongoId Currency { get; set; }
 
     [JsonPropertyName("currency_coefficient")]
     public double? CurrencyCoefficient { get; set; }
diff --git a/Libraries/SPTarkov.Server.Core/Models/Eft/Ragfair/GetOffersResult.cs b/Libraries/SPTarkov.Server.Core/Models/Eft/Ragfair/GetOffersResult.cs
index 8c4f57f7..3683bd12 100644
--- a/Libraries/SPTarkov.Server.Core/Models/Eft/Ragfair/GetOffersResult.cs
+++ b/Libraries/SPTarkov.Server.Core/Models/Eft/Ragfair/GetOffersResult.cs
@@ -1,4 +1,5 @@
 using System.Text.Json.Serialization;
+using SPTarkov.Server.Core.Models.Common;
 
 namespace SPTarkov.Server.Core.Models.Eft.Ragfair;
 
@@ -8,7 +9,7 @@ public record GetOffersResult
     public Dictionary<string, object>? ExtensionData { get; set; }
 
     [JsonPropertyName("categories")]
-    public Dictionary<string, int>? Categories { get; set; }
+    public Dictionary<MongoId, int>? Categories { get; set; }
 
     [JsonPropertyName("offers")]
     public List<RagfairOffer>? Offers { get; set; }
diff --git a/Libraries/SPTarkov.Server.Core/Servers/RagfairServer.cs b/Libraries/SPTarkov.Server.Core/Servers/RagfairServer.cs
index 09f44ce2..fb9f9349 100644
--- a/Libraries/SPTarkov.Server.Core/Servers/RagfairServer.cs
+++ b/Libraries/SPTarkov.Server.Core/Servers/RagfairServer.cs
@@ -1,5 +1,6 @@
 using SPTarkov.DI.Annotations;
 using SPTarkov.Server.Core.Generators;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Eft.Ragfair;
 using SPTarkov.Server.Core.Models.Enums;
 using SPTarkov.Server.Core.Models.Spt.Config;
@@ -81,7 +82,7 @@ public class RagfairServer(
         return _ragfairConfig.Traders.Keys.ToList();
     }
 
-    public Dictionary<string, int> GetAllActiveCategories(
+    public Dictionary<MongoId, int> GetAllActiveCategories(
         bool fleaUnlocked,
         SearchRequestData searchRequestData,
         List<RagfairOffer> offers
diff --git a/Libraries/SPTarkov.Server.Core/Services/CircleOfCultistService.cs b/Libraries/SPTarkov.Server.Core/Services/CircleOfCultistService.cs
index cc3a0450..1f6bea9a 100644
--- a/Libraries/SPTarkov.Server.Core/Services/CircleOfCultistService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/CircleOfCultistService.cs
@@ -2,6 +2,7 @@ using SPTarkov.Common.Extensions;
 using SPTarkov.DI.Annotations;
 using SPTarkov.Server.Core.Extensions;
 using SPTarkov.Server.Core.Helpers;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Eft.Common;
 using SPTarkov.Server.Core.Models.Eft.Common.Tables;
 using SPTarkov.Server.Core.Models.Eft.Hideout;
@@ -552,7 +553,7 @@ public class CircleOfCultistService(
     )
     {
         // Get sacrificed tpls
-        IEnumerable<string> sacrificedItemTpls = sacrificedItems
+        IEnumerable<MongoId> sacrificedItemTpls = sacrificedItems
             .Select(item => item.Template)
             .Where(item => item != null);
         // Create md5 key of the items player sacrificed so we can compare against the direct reward cache
@@ -964,12 +965,23 @@ public class CircleOfCultistService(
         return requirements.Where(requirement => requirement.Type == "Item").ToList();
     }
 
+    /// <summary>
+    /// Temporary until MongoId conversion is done, should be removed and the mongoid one kept in place
+    /// </summary>
+    /// <param name="requiredItems"></param>
+    /// <returns></returns>
     protected string CreateSacrificeCacheKey(IEnumerable<string> requiredItems)
     {
         var concat = string.Join(",", requiredItems.OrderBy(item => item));
         return _hashUtil.GenerateHashForData(HashingAlgorithm.MD5, concat);
     }
 
+    protected string CreateSacrificeCacheKey(IEnumerable<MongoId> requiredItems)
+    {
+        var concat = string.Join(",", requiredItems.OrderBy(item => item));
+        return _hashUtil.GenerateHashForData(HashingAlgorithm.MD5, concat);
+    }
+
     /// <summary>
     ///     Create a map of the possible direct rewards, keyed by the items needed to be sacrificed
     /// </summary>
diff --git a/Libraries/SPTarkov.Server.Core/Services/RagfairCategoriesService.cs b/Libraries/SPTarkov.Server.Core/Services/RagfairCategoriesService.cs
index b42fd63a..72081d93 100644
--- a/Libraries/SPTarkov.Server.Core/Services/RagfairCategoriesService.cs
+++ b/Libraries/SPTarkov.Server.Core/Services/RagfairCategoriesService.cs
@@ -1,5 +1,6 @@
 using SPTarkov.DI.Annotations;
 using SPTarkov.Server.Core.Helpers;
+using SPTarkov.Server.Core.Models.Common;
 using SPTarkov.Server.Core.Models.Eft.Ragfair;
 using SPTarkov.Server.Core.Models.Enums;
 using SPTarkov.Server.Core.Models.Utils;
@@ -19,7 +20,7 @@ public class RagfairCategoriesService(
     /// <param name="searchRequestData">Search criteria requested</param>
     /// <param name="fleaUnlocked">Can player see full flea yet (level 15 by default)</param>
     /// <returns>KVP of item tpls + count of offers</returns>
-    public Dictionary<string, int> GetCategoriesFromOffers(
+    public Dictionary<MongoId, int> GetCategoriesFromOffers(
         List<RagfairOffer> offers,
         SearchRequestData searchRequestData,
         bool fleaUnlocked
diff --git a/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/SptJsonConverterRegistrator.cs b/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/SptJsonConverterRegistrator.cs
index a16f736e..1491f9c5 100644
--- a/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/SptJsonConverterRegistrator.cs
+++ b/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/SptJsonConverterRegistrator.cs
@@ -16,6 +16,7 @@ public class SptJsonConverterRegistrator : IJsonConverterRegistrator
             new DictionaryOrListConverter(),
             new EftEnumConverter<LogLevel>(), // Special case, this belongs to a lib.
             new BaseInteractionRequestDataConverter(),
+            new StringToMongoIdConverter(),
             .. GetGenericJsonConverters(),
         ];
     }
diff --git a/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/StringToMongoIdConverter.cs b/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/StringToMongoIdConverter.cs
new file mode 100644
index 00000000..aa4684aa
--- /dev/null
+++ b/Libraries/SPTarkov.Server.Core/Utils/Json/Converters/StringToMongoIdConverter.cs
@@ -0,0 +1,52 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using SPTarkov.Server.Core.Models.Common;
+
+namespace SPTarkov.Server.Core.Utils.Json.Converters
+{
+    public class StringToMongoIdConverter : JsonConverter<MongoId>
+    {
+        public override MongoId Read(
+            ref Utf8JsonReader reader,
+            Type typeToConvert,
+            JsonSerializerOptions options
+        )
+        {
+            if (reader.TokenType == JsonTokenType.String)
+            {
+                return new MongoId(reader.GetString());
+            }
+
+            throw new JsonException();
+        }
+
+        public override void Write(
+            Utf8JsonWriter writer,
+            MongoId mongoId,
+            JsonSerializerOptions options
+        )
+        {
+            JsonSerializer.Serialize(writer, mongoId.ToString(), options);
+        }
+
+        // Deserialize MongoId as a dictionary key
+        public override MongoId ReadAsPropertyName(
+            ref Utf8JsonReader reader,
+            Type typeToConvert,
+            JsonSerializerOptions options
+        )
+        {
+            return new MongoId(reader.GetString());
+        }
+
+        // Serialize MongoId as a dictionary key
+        public override void WriteAsPropertyName(
+            Utf8JsonWriter writer,
+            MongoId value,
+            JsonSerializerOptions options
+        )
+        {
+            writer.WritePropertyName(value.ToString());
+        }
+    }
+}