diff --git a/src/ProjectOrigin.WalletSystem.IntegrationTests/ApiTests/ApiTests.open_api_specification_not_changed.verified.txt b/src/ProjectOrigin.WalletSystem.IntegrationTests/ApiTests/ApiTests.open_api_specification_not_changed.verified.txt
index 969fbbcb..7dde4053 100644
--- a/src/ProjectOrigin.WalletSystem.IntegrationTests/ApiTests/ApiTests.open_api_specification_not_changed.verified.txt
+++ b/src/ProjectOrigin.WalletSystem.IntegrationTests/ApiTests/ApiTests.open_api_specification_not_changed.verified.txt
@@ -13,7 +13,7 @@
         "summary": "Gets all certificates in the wallet that are <b>available</b> for use.",
         "parameters": [
           {
-            "name": "start",
+            "name": "Start",
             "in": "query",
             "description": "The start of the time range in Unix time in seconds.",
             "schema": {
@@ -22,7 +22,7 @@
             }
           },
           {
-            "name": "end",
+            "name": "End",
             "in": "query",
             "description": "The end of the time range in Unix time in seconds.",
             "schema": {
@@ -31,7 +31,7 @@
             }
           },
           {
-            "name": "type",
+            "name": "Type",
             "in": "query",
             "description": "Filter the type of certificates to return.",
             "schema": {
@@ -39,7 +39,7 @@
             }
           },
           {
-            "name": "limit",
+            "name": "Limit",
             "in": "query",
             "description": "The number of items to return.",
             "schema": {
@@ -48,7 +48,7 @@
             }
           },
           {
-            "name": "skip",
+            "name": "Skip",
             "in": "query",
             "description": "The number of items to skip.",
             "schema": {
@@ -83,15 +83,15 @@
         "summary": "Returns aggregates certificates that are <b>available</b> to use, based on the specified time zone and time range.",
         "parameters": [
           {
-            "name": "timeAggregate",
+            "name": "TimeAggregate",
             "in": "query",
-            "description": "The size of each bucket in the aggregation",
+            "description": "The size of each bucket in the aggregation.",
             "schema": {
               "$ref": "#/components/schemas/TimeAggregate"
             }
           },
           {
-            "name": "timeZone",
+            "name": "TimeZone",
             "in": "query",
             "description": "The time zone. See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of valid time zones.",
             "schema": {
@@ -99,7 +99,7 @@
             }
           },
           {
-            "name": "start",
+            "name": "Start",
             "in": "query",
             "description": "The start of the time range in Unix time in seconds.",
             "schema": {
@@ -108,7 +108,7 @@
             }
           },
           {
-            "name": "end",
+            "name": "End",
             "in": "query",
             "description": "The end of the time range in Unix time in seconds.",
             "schema": {
@@ -117,7 +117,7 @@
             }
           },
           {
-            "name": "type",
+            "name": "Type",
             "in": "query",
             "description": "Filter the type of certificates to return.",
             "schema": {
@@ -125,7 +125,7 @@
             }
           },
           {
-            "name": "limit",
+            "name": "Limit",
             "in": "query",
             "description": "The number of items to return.",
             "schema": {
@@ -134,7 +134,7 @@
             }
           },
           {
-            "name": "skip",
+            "name": "Skip",
             "in": "query",
             "description": "The number of items to skip.",
             "schema": {
@@ -172,7 +172,7 @@
         "summary": "Gets all claims in the wallet",
         "parameters": [
           {
-            "name": "start",
+            "name": "Start",
             "in": "query",
             "description": "The start of the time range in Unix time in seconds.",
             "schema": {
@@ -181,7 +181,7 @@
             }
           },
           {
-            "name": "end",
+            "name": "End",
             "in": "query",
             "description": "The end of the time range in Unix time in seconds.",
             "schema": {
@@ -190,7 +190,7 @@
             }
           },
           {
-            "name": "limit",
+            "name": "Limit",
             "in": "query",
             "description": "The number of items to return.",
             "schema": {
@@ -199,7 +199,7 @@
             }
           },
           {
-            "name": "skip",
+            "name": "Skip",
             "in": "query",
             "description": "The number of items to skip.",
             "schema": {
@@ -275,7 +275,7 @@
         "summary": "Returns a list of aggregates claims for the authenticated user based on the specified time zone and time range.",
         "parameters": [
           {
-            "name": "timeAggregate",
+            "name": "TimeAggregate",
             "in": "query",
             "description": "The size of each bucket in the aggregation",
             "schema": {
@@ -283,7 +283,7 @@
             }
           },
           {
-            "name": "timeZone",
+            "name": "TimeZone",
             "in": "query",
             "description": "The time zone. See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of valid time zones.",
             "schema": {
@@ -291,7 +291,7 @@
             }
           },
           {
-            "name": "start",
+            "name": "Start",
             "in": "query",
             "description": "The start of the time range in Unix time in seconds.",
             "schema": {
@@ -300,7 +300,7 @@
             }
           },
           {
-            "name": "end",
+            "name": "End",
             "in": "query",
             "description": "The end of the time range in Unix time in seconds.",
             "schema": {
@@ -309,7 +309,7 @@
             }
           },
           {
-            "name": "limit",
+            "name": "Limit",
             "in": "query",
             "description": "The number of items to return.",
             "schema": {
@@ -318,7 +318,7 @@
             }
           },
           {
-            "name": "skip",
+            "name": "Skip",
             "in": "query",
             "description": "The number of items to skip.",
             "schema": {
diff --git a/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/CertificatesControllerTests.cs b/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/CertificatesControllerTests.cs
index 06baa14c..356688c4 100644
--- a/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/CertificatesControllerTests.cs
+++ b/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/CertificatesControllerTests.cs
@@ -34,12 +34,7 @@ public async Task Verify_Unauthorized()
         var controller = new CertificatesController();
 
         // Act
-        var result = await controller.GetCertificates(
-            _unitOfWork,
-            null,
-            null,
-            null,
-            null);
+        var result = await controller.GetCertificates(_unitOfWork, new GetCertificatesQueryParameters());
 
         // Assert
         result.Result.Should().BeOfType<UnauthorizedResult>();
@@ -88,12 +83,14 @@ public async Task Test_AggregateCertificates(string timezone, long[] values, Cer
         // Act
         var result = await controller.AggregateCertificates(
             _unitOfWork,
-            TimeAggregate.Day,
-            timezone,
-            queryStartDate.ToUnixTimeSeconds(),
-            queryEndDate.ToUnixTimeSeconds(),
-            type,
-            null);
+            new AggregateCertificatesQueryParameters
+            {
+                TimeAggregate = TimeAggregate.Day,
+                TimeZone = timezone,
+                Start = queryStartDate.ToUnixTimeSeconds(),
+                End = queryEndDate.ToUnixTimeSeconds(),
+                Type = type
+            });
 
         // Assert
         result.Value.Should().NotBeNull();
@@ -116,12 +113,11 @@ public async Task AggregateCertificates_Invalid_TimeZone()
         // Act
         var result = await controller.AggregateCertificates(
             _unitOfWork,
-            TimeAggregate.Day,
-            "invalid-time-zone",
-            null,
-            null,
-            null,
-            null);
+            new AggregateCertificatesQueryParameters
+            {
+                TimeAggregate = TimeAggregate.Day,
+                TimeZone = "invalid-time-zone",
+            });
 
         // Assert
         result.Result.Should().BeOfType<BadRequestObjectResult>();
diff --git a/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/ClaimsControllerTests.cs b/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/ClaimsControllerTests.cs
index 28edff29..68a7a7a9 100644
--- a/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/ClaimsControllerTests.cs
+++ b/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/ClaimsControllerTests.cs
@@ -40,9 +40,7 @@ public async Task Verify_Unauthorized()
         // Act
         var result = await controller.GetClaims(
             _unitOfWork,
-            null,
-            null,
-            null);
+            new GetClaimsQueryParameters());
 
         // Assert
         result.Result.Should().BeOfType<UnauthorizedResult>();
@@ -93,11 +91,13 @@ public async Task Test_AggregateClaims(string timezone, long[] values)
         // Act
         var result = await controller.AggregateClaims(
             _unitOfWork,
-            TimeAggregate.Day,
-            timezone,
-            queryStartDate.ToUnixTimeSeconds(),
-            queryEndDate.ToUnixTimeSeconds(),
-            null);
+            new AggregateClaimsQueryParameters
+            {
+                TimeAggregate = TimeAggregate.Day,
+                TimeZone = timezone,
+                Start = queryStartDate.ToUnixTimeSeconds(),
+                End = queryEndDate.ToUnixTimeSeconds()
+            });
 
         // Assert
         result.Value.Should().NotBeNull();
@@ -120,11 +120,11 @@ public async Task AggregateClaims_Invalid_TimeZone()
         // Act
         var result = await controller.AggregateClaims(
             _unitOfWork,
-            TimeAggregate.Day,
-            "invalid-time-zone",
-            null,
-            null,
-            null);
+            new AggregateClaimsQueryParameters
+            {
+                TimeAggregate = TimeAggregate.Day,
+                TimeZone = "invalid-time-zone"
+            });
 
         // Assert
         result.Result.Should().BeOfType<BadRequestObjectResult>();
diff --git a/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/WalletControllerTests.cs b/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/WalletControllerTests.cs
index 918b7a13..9d4345e6 100644
--- a/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/WalletControllerTests.cs
+++ b/src/ProjectOrigin.WalletSystem.IntegrationTests/REST/WalletControllerTests.cs
@@ -139,7 +139,7 @@ public async Task Verify_Valid()
     }
 
     [Fact]
-    public async Task Verify_OnlySingleAllowedPerSubject()
+    public async Task Verify_MultipleWalletsAllowedPerSubject()
     {
         // Arrange
         var subject = _fixture.Create<string>();
@@ -154,7 +154,8 @@ public async Task Verify_OnlySingleAllowedPerSubject()
             _options,
             new CreateWalletRequest());
 
-        firstCreateResult.Result.Should().BeOfType<CreatedResult>();
+        var firstResponse = firstCreateResult.Result.Should().BeOfType<CreatedResult>()
+                .Which.Value.Should().BeOfType<CreateWalletResponse>().Which;
 
         // Act
         var secondCreateResult = await controller.CreateWallet(
@@ -164,8 +165,9 @@ public async Task Verify_OnlySingleAllowedPerSubject()
             new CreateWalletRequest());
 
         // Assert
-        secondCreateResult.Result.Should().BeOfType<BadRequestObjectResult>()
-            .Which.Value.Should().Be("Wallet already exists.");
+        var secondResponse = secondCreateResult.Result.Should().BeOfType<CreatedResult>()
+                .Which.Value.Should().BeOfType<CreateWalletResponse>().Which;
+        firstResponse.WalletId.Should().NotBe(secondResponse.WalletId);
     }
 
     [Fact]
diff --git a/src/ProjectOrigin.WalletSystem.IntegrationTests/Repositories/CertificateRepositoryTests.cs b/src/ProjectOrigin.WalletSystem.IntegrationTests/Repositories/CertificateRepositoryTests.cs
index 275d4f06..b7f18cdc 100644
--- a/src/ProjectOrigin.WalletSystem.IntegrationTests/Repositories/CertificateRepositoryTests.cs
+++ b/src/ProjectOrigin.WalletSystem.IntegrationTests/Repositories/CertificateRepositoryTests.cs
@@ -417,22 +417,8 @@ public async Task GetAvailableSlice()
     {
         var registry = _fixture.Create<string>();
         var wallet1 = await CreateWallet(_fixture.Create<string>());
-        var endpointPosition = 1;
-        var endpoint = await CreateWalletEndpoint(wallet1);
-        var certificate = await CreateCertificate(registry);
-        var slice = new WalletSlice
-        {
-            Id = Guid.NewGuid(),
-            WalletEndpointId = endpoint.Id,
-            WalletEndpointPosition = endpointPosition,
-            RegistryName = registry,
-            CertificateId = certificate.Id,
-            Quantity = _fixture.Create<int>(),
-            RandomR = _fixture.Create<byte[]>(),
-            State = WalletSliceState.Available
-        };
 
-        await _certRepository.InsertWalletSlice(slice);
+        var slice = await CreateAndInsertCertificateWithSlice(registry, await CreateWalletEndpoint(wallet1), 1);
 
         var sliceDb = await _certRepository.GetOwnersAvailableSlices(registry, slice.CertificateId, wallet1.Owner);
 
@@ -440,6 +426,25 @@ public async Task GetAvailableSlice()
         sliceDb.Should().ContainEquivalentOf(slice);
     }
 
+    [Fact]
+    public async Task QueryAvailableCertificates_MultipleWallets()
+    {
+        var registry = _fixture.Create<string>();
+        var subject = _fixture.Create<string>();
+        var wallet1 = await CreateWallet(subject);
+        var wallet2 = await CreateWallet(subject);
+        var slice1 = await CreateAndInsertCertificateWithSlice(registry, await CreateWalletEndpoint(wallet1), 1);
+        var slice2 = await CreateAndInsertCertificateWithSlice(registry, await CreateWalletEndpoint(wallet2), 1);
+
+        var result = await _certRepository.QueryAvailableCertificates(new CertificatesFilter
+        {
+            Owner = subject
+        });
+
+        result.Count.Should().Be(2);
+        result.Items.Sum(x => x.Quantity).Should().Be(slice1.Quantity + slice2.Quantity);
+    }
+
     [Fact]
     public async Task GetAvailableSlice_WhenSliceStateOtherThanAvailable_ExpectNull()
     {
@@ -513,25 +518,12 @@ public async Task ReserveSlice()
     {
         // Arrange
         var registry = _fixture.Create<string>();
-        var certificate = await CreateCertificate(registry);
         var owner = _fixture.Create<string>();
         var wallet = await CreateWallet(owner);
-        var endpoint = await CreateWalletEndpoint(wallet);
-        var slice = new WalletSlice
-        {
-            Id = Guid.NewGuid(),
-            WalletEndpointId = endpoint.Id,
-            WalletEndpointPosition = 1,
-            RegistryName = registry,
-            CertificateId = certificate.Id,
-            Quantity = 150,
-            RandomR = _fixture.Create<byte[]>(),
-            State = WalletSliceState.Available
-        };
-        await _certRepository.InsertWalletSlice(slice);
+        var slice = await CreateAndInsertCertificateWithSlice(registry, await CreateWalletEndpoint(wallet), 1, quantity: 150);
 
         // Act
-        var reservedSlices = await _certRepository.ReserveQuantity(owner, certificate.RegistryName, certificate.Id, 100);
+        var reservedSlices = await _certRepository.ReserveQuantity(owner, slice.RegistryName, slice.CertificateId, 100);
 
         // Assert
         reservedSlices.Should().ContainEquivalentOf(slice);
@@ -557,25 +549,13 @@ public async Task ReserveSlice_LessThan_ThrowsException()
     {
         // Arrange
         var registry = _fixture.Create<string>();
-        var certificate = await CreateCertificate(registry);
         var owner = _fixture.Create<string>();
         var wallet = await CreateWallet(owner);
         var endpoint = await CreateWalletEndpoint(wallet);
-        var slice = new WalletSlice
-        {
-            Id = Guid.NewGuid(),
-            WalletEndpointId = endpoint.Id,
-            WalletEndpointPosition = 1,
-            RegistryName = registry,
-            CertificateId = certificate.Id,
-            Quantity = 150,
-            RandomR = _fixture.Create<byte[]>(),
-            State = WalletSliceState.Available
-        };
-        await _certRepository.InsertWalletSlice(slice);
+        var slice = await CreateAndInsertCertificateWithSlice(registry, await CreateWalletEndpoint(wallet), 1, quantity: 150);
 
         // Act
-        var act = () => _certRepository.ReserveQuantity(owner, certificate.RegistryName, certificate.Id, 200);
+        var act = () => _certRepository.ReserveQuantity(owner, slice.RegistryName, slice.CertificateId, 200);
 
         // Assert
         await act.Should().ThrowAsync<InvalidOperationException>().WithMessage("Owner has less to reserve than available");
@@ -586,22 +566,10 @@ public async Task ReserveSlice_ToBe_ThrowsException()
     {
         // Arrange
         var registry = _fixture.Create<string>();
-        var certificate = await CreateCertificate(registry);
         var owner = _fixture.Create<string>();
         var wallet = await CreateWallet(owner);
-        var endpoint = await CreateWalletEndpoint(wallet);
-        var slice = new WalletSlice
-        {
-            Id = Guid.NewGuid(),
-            WalletEndpointId = endpoint.Id,
-            WalletEndpointPosition = 1,
-            RegistryName = registry,
-            CertificateId = certificate.Id,
-            Quantity = 150,
-            RandomR = _fixture.Create<byte[]>(),
-            State = WalletSliceState.Available
-        };
-        await _certRepository.InsertWalletSlice(slice);
+
+        var slice = await CreateAndInsertCertificateWithSlice(registry, await CreateWalletEndpoint(wallet), 1, quantity: 150);
         await _certRepository.InsertWalletSlice(slice with
         {
             Id = Guid.NewGuid(),
@@ -611,7 +579,7 @@ await _certRepository.InsertWalletSlice(slice with
         });
 
         // Act
-        var act = () => _certRepository.ReserveQuantity(owner, certificate.RegistryName, certificate.Id, 200);
+        var act = () => _certRepository.ReserveQuantity(owner, slice.RegistryName, slice.CertificateId, 200);
 
         // Assert
         await act.Should().ThrowAsync<TransientException>().WithMessage("Owner has enough quantity, but it is not yet available to reserve");
@@ -748,4 +716,30 @@ private async Task CreateCertificatesAndSlices(Wallet wallet, int numberOfCertif
             await _certRepository.InsertWalletSlice(slice);
         }
     }
+
+    private async Task<WalletSlice> CreateAndInsertCertificateWithSlice(
+        string registry,
+        WalletEndpoint endpoint,
+        int endpointPosition,
+        int? quantity = null)
+    {
+        quantity = quantity ?? _fixture.Create<int>();
+
+        var certificate = await CreateCertificate(registry);
+        var slice = new WalletSlice
+        {
+            Id = Guid.NewGuid(),
+            WalletEndpointId = endpoint.Id,
+            WalletEndpointPosition = endpointPosition,
+            RegistryName = registry,
+            CertificateId = certificate.Id,
+            Quantity = quantity.Value,
+            RandomR = _fixture.Create<byte[]>(),
+            State = WalletSliceState.Available
+        };
+
+        await _certRepository.InsertWalletSlice(slice);
+
+        return slice;
+    }
 }
diff --git a/src/ProjectOrigin.WalletSystem.Server/Database/Postgres/Scripts/v2/v2-0005.sql b/src/ProjectOrigin.WalletSystem.Server/Database/Postgres/Scripts/v2/v2-0005.sql
new file mode 100644
index 00000000..523b5abd
--- /dev/null
+++ b/src/ProjectOrigin.WalletSystem.Server/Database/Postgres/Scripts/v2/v2-0005.sql
@@ -0,0 +1,2 @@
+-- Modify the wallets table to remove the unique constraint on the owner column
+ALTER TABLE wallets DROP CONSTRAINT wallets_owner_key1;
diff --git a/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/CertificatesController.cs b/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/CertificatesController.cs
index 19969fb2..b53e7ebf 100644
--- a/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/CertificatesController.cs
+++ b/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/CertificatesController.cs
@@ -1,6 +1,6 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
+using System.ComponentModel;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Http;
@@ -18,12 +18,6 @@ public class CertificatesController : ControllerBase
     /// <summary>
     /// Gets all certificates in the wallet that are <b>available</b> for use.
     /// </summary>
-    /// <param name="unitOfWork"></param>
-    /// <param name="start">The start of the time range in Unix time in seconds.</param>
-    /// <param name="end">The end of the time range in Unix time in seconds.</param>
-    /// <param name="type">Filter the type of certificates to return.</param>
-    /// <param name="skip">The number of items to skip.</param>
-    /// <param name="limit">The number of items to return.</param>
     /// <response code="200">Returns the aggregated claims.</response>
     /// <response code="401">If the user is not authenticated.</response>
     [HttpGet]
@@ -33,22 +27,18 @@ public class CertificatesController : ControllerBase
     [ProducesResponseType(typeof(void), StatusCodes.Status401Unauthorized)]
     public async Task<ActionResult<ResultList<GranularCertificate>>> GetCertificates(
         [FromServices] IUnitOfWork unitOfWork,
-        [FromQuery] long? start,
-        [FromQuery] long? end,
-        [FromQuery] CertificateType? type,
-        [FromQuery] int? limit,
-        [FromQuery] int skip = 0)
+        [FromQuery] GetCertificatesQueryParameters param)
     {
         if (!User.TryGetSubject(out var subject)) return Unauthorized();
 
         var certificates = await unitOfWork.CertificateRepository.QueryAvailableCertificates(new CertificatesFilter
         {
             Owner = subject,
-            Start = start != null ? DateTimeOffset.FromUnixTimeSeconds(start.Value) : null,
-            End = end != null ? DateTimeOffset.FromUnixTimeSeconds(end.Value) : null,
-            Type = type != null ? (GranularCertificateType)type.Value : null,
-            Skip = skip,
-            Limit = limit ?? int.MaxValue
+            Start = param.Start != null ? DateTimeOffset.FromUnixTimeSeconds(param.Start.Value) : null,
+            End = param.End != null ? DateTimeOffset.FromUnixTimeSeconds(param.End.Value) : null,
+            Type = param.Type != null ? (GranularCertificateType)param.Type.Value : null,
+            Skip = param.Skip,
+            Limit = param.Limit ?? int.MaxValue
         });
 
         return certificates.ToResultList(c => c.MapToV1());
@@ -57,14 +47,6 @@ public async Task<ActionResult<ResultList<GranularCertificate>>> GetCertificates
     /// <summary>
     /// Returns aggregates certificates that are <b>available</b> to use, based on the specified time zone and time range.
     /// </summary>
-    /// <param name="unitOfWork"></param>
-    /// <param name="timeAggregate">The size of each bucket in the aggregation</param>
-    /// <param name="timeZone">The time zone. See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of valid time zones.</param>
-    /// <param name="start">The start of the time range in Unix time in seconds.</param>
-    /// <param name="end">The end of the time range in Unix time in seconds.</param>
-    /// <param name="type">Filter the type of certificates to return.</param>
-    /// <param name="skip">The number of items to skip.</param>
-    /// <param name="limit">The number of items to return.</param>
     /// <response code="200">Returns the aggregated claims.</response>
     /// <response code="400">If the time zone is invalid.</response>
     /// <response code="401">If the user is not authenticated.</response>
@@ -76,26 +58,22 @@ public async Task<ActionResult<ResultList<GranularCertificate>>> GetCertificates
     [ProducesResponseType(typeof(void), StatusCodes.Status401Unauthorized)]
     public async Task<ActionResult<ResultList<AggregatedCertificates>>> AggregateCertificates(
         [FromServices] IUnitOfWork unitOfWork,
-        [FromQuery] TimeAggregate timeAggregate,
-        [FromQuery] string timeZone,
-        [FromQuery] long? start,
-        [FromQuery] long? end,
-        [FromQuery] CertificateType? type,
-        [FromQuery] int? limit,
-        [FromQuery] int skip = 0)
+        [FromQuery] AggregateCertificatesQueryParameters parameters)
     {
         if (!User.TryGetSubject(out var subject)) return Unauthorized();
-        if (!timeZone.TryParseTimeZone(out var timeZoneInfo)) return BadRequest("Invalid time zone");
+        if (!parameters.TimeZone.TryParseTimeZone(out var timeZoneInfo)) return BadRequest("Invalid time zone");
 
         var certificates = await unitOfWork.CertificateRepository.QueryAggregatedAvailableCertificates(new CertificatesFilter
         {
             Owner = subject,
-            Start = start != null ? DateTimeOffset.FromUnixTimeSeconds(start.Value) : null,
-            End = end != null ? DateTimeOffset.FromUnixTimeSeconds(end.Value) : null,
-            Type = type != null ? (GranularCertificateType)type.Value : null,
-            Skip = skip,
-            Limit = limit ?? int.MaxValue
-        }, (Models.TimeAggregate)timeAggregate, timeZone);
+            Start = parameters.Start != null ? DateTimeOffset.FromUnixTimeSeconds(parameters.Start.Value) : null,
+            End = parameters.End != null ? DateTimeOffset.FromUnixTimeSeconds(parameters.End.Value) : null,
+            Type = parameters.Type != null ? (GranularCertificateType)parameters.Type.Value : null,
+            Skip = parameters.Skip,
+            Limit = parameters.Limit ?? int.MaxValue
+        },
+        (Models.TimeAggregate)parameters.TimeAggregate,
+        parameters.TimeZone);
 
         return certificates.ToResultList(c => new AggregatedCertificates
         {
@@ -108,6 +86,73 @@ public async Task<ActionResult<ResultList<AggregatedCertificates>>> AggregateCer
 }
 
 #region Records
+public record GetCertificatesQueryParameters
+{
+    /// <summary>
+    /// The start of the time range in Unix time in seconds.
+    /// </summary>
+    public long? Start { get; init; }
+
+    /// <summary>
+    /// The end of the time range in Unix time in seconds.
+    /// </summary>
+    public long? End { get; init; }
+
+    /// <summary>
+    /// Filter the type of certificates to return.
+    /// </summary>
+    public CertificateType? Type { get; init; }
+
+    /// <summary>
+    /// The number of items to return.
+    /// </summary>
+    public int? Limit { get; init; }
+
+    /// <summary>
+    /// The number of items to skip.
+    /// </summary>
+    [DefaultValue(0)]
+    public int Skip { get; init; }
+}
+
+public record AggregateCertificatesQueryParameters
+{
+    /// <summary>
+    /// The size of each bucket in the aggregation.
+    /// </summary>
+    public required TimeAggregate TimeAggregate { get; init; }
+
+    /// <summary>
+    /// The time zone. See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of valid time zones.
+    /// </summary>
+    public required string TimeZone { get; init; }
+
+    /// <summary>
+    ///The start of the time range in Unix time in seconds.
+    /// </summary>
+    public long? Start { get; init; }
+
+    /// <summary>
+    /// The end of the time range in Unix time in seconds.
+    /// </summary>
+    public long? End { get; init; }
+
+    /// <summary>
+    /// Filter the type of certificates to return.
+    /// </summary>
+    public CertificateType? Type { get; init; }
+
+    /// <summary>
+    /// The number of items to return.
+    /// </summary>
+    public int? Limit { get; init; }
+
+    /// <summary>
+    /// The number of items to skip.
+    /// </summary>
+    [DefaultValue(0)]
+    public int Skip { get; init; }
+}
 
 /// <summary>
 /// A certificate that is available to use in the wallet.
diff --git a/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/ClaimsController.cs b/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/ClaimsController.cs
index c356da44..65742067 100644
--- a/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/ClaimsController.cs
+++ b/src/ProjectOrigin.WalletSystem.Server/Services/REST/v1/ClaimsController.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Linq;
 using System.Threading.Tasks;
 using MassTransit;
@@ -20,11 +21,6 @@ public class ClaimsController : ControllerBase
     /// <summary>
     /// Gets all claims in the wallet
     /// </summary>
-    /// <param name="unitOfWork"></param>
-    /// <param name="start">The start of the time range in Unix time in seconds.</param>
-    /// <param name="end">The end of the time range in Unix time in seconds.</param>
-    /// <param name="skip">The number of items to skip.</param>
-    /// <param name="limit">The number of items to return.</param>
     /// <response code="200">Returns all the indiviual claims.</response>
     /// <response code="401">If the user is not authenticated.</response>
     [HttpGet]
@@ -34,20 +30,17 @@ public class ClaimsController : ControllerBase
     [ProducesResponseType(typeof(void), StatusCodes.Status401Unauthorized)]
     public async Task<ActionResult<ResultList<Claim>>> GetClaims(
         [FromServices] IUnitOfWork unitOfWork,
-        [FromQuery] long? start,
-        [FromQuery] long? end,
-        [FromQuery] int? limit,
-        [FromQuery] int skip = 0)
+        [FromQuery] GetClaimsQueryParameters param)
     {
         if (!User.TryGetSubject(out var subject)) return Unauthorized();
 
         var claims = await unitOfWork.ClaimRepository.QueryClaims(new ClaimFilter
         {
             Owner = subject,
-            Start = start != null ? DateTimeOffset.FromUnixTimeSeconds(start.Value) : null,
-            End = end != null ? DateTimeOffset.FromUnixTimeSeconds(end.Value) : null,
-            Skip = skip,
-            Limit = limit ?? int.MaxValue,
+            Start = param.Start != null ? DateTimeOffset.FromUnixTimeSeconds(param.Start.Value) : null,
+            End = param.End != null ? DateTimeOffset.FromUnixTimeSeconds(param.End.Value) : null,
+            Skip = param.Skip,
+            Limit = param.Limit ?? int.MaxValue,
         });
 
         return claims.ToResultList(c => c.MapToV1());
@@ -56,13 +49,6 @@ public async Task<ActionResult<ResultList<Claim>>> GetClaims(
     /// <summary>
     /// Returns a list of aggregates claims for the authenticated user based on the specified time zone and time range.
     /// </summary>
-    /// <param name="unitOfWork"></param>
-    /// <param name="timeAggregate">The size of each bucket in the aggregation</param>
-    /// <param name="timeZone">The time zone. See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of valid time zones.</param>
-    /// <param name="start">The start of the time range in Unix time in seconds.</param>
-    /// <param name="end">The end of the time range in Unix time in seconds.</param>
-    /// <param name="skip">The number of items to skip.</param>
-    /// <param name="limit">The number of items to return.</param>
     /// <response code="200">Returns the aggregated claims.</response>
     /// <response code="400">If the time zone is invalid.</response>
     /// <response code="401">If the user is not authenticated.</response>
@@ -74,24 +60,19 @@ public async Task<ActionResult<ResultList<Claim>>> GetClaims(
     [ProducesResponseType(typeof(void), StatusCodes.Status401Unauthorized)]
     public async Task<ActionResult<ResultList<AggregatedClaims>>> AggregateClaims(
         [FromServices] IUnitOfWork unitOfWork,
-        [FromQuery] TimeAggregate timeAggregate,
-        [FromQuery] string timeZone,
-        [FromQuery] long? start,
-        [FromQuery] long? end,
-        [FromQuery] int? limit,
-        [FromQuery] int skip = 0)
+        [FromQuery] AggregateClaimsQueryParameters param)
     {
         if (!User.TryGetSubject(out var subject)) return Unauthorized();
-        if (!timeZone.TryParseTimeZone(out var timeZoneInfo)) return BadRequest("Invalid time zone");
+        if (!param.TimeZone.TryParseTimeZone(out var timeZoneInfo)) return BadRequest("Invalid time zone");
 
         var result = await unitOfWork.ClaimRepository.QueryAggregatedClaims(new ClaimFilter
         {
             Owner = subject,
-            Start = start != null ? DateTimeOffset.FromUnixTimeSeconds(start.Value) : null,
-            End = end != null ? DateTimeOffset.FromUnixTimeSeconds(end.Value) : null,
-            Skip = skip,
-            Limit = limit ?? int.MaxValue
-        }, (Models.TimeAggregate)timeAggregate, timeZone);
+            Start = param.Start != null ? DateTimeOffset.FromUnixTimeSeconds(param.Start.Value) : null,
+            End = param.End != null ? DateTimeOffset.FromUnixTimeSeconds(param.End.Value) : null,
+            Skip = param.Skip,
+            Limit = param.Limit ?? int.MaxValue
+        }, (Models.TimeAggregate)param.TimeAggregate, param.TimeZone);
 
         return result.ToResultList(c => new AggregatedClaims()
         {
@@ -142,6 +123,64 @@ [FromBody] ClaimRequest request
 
 #region Records
 
+public record GetClaimsQueryParameters
+{
+    /// <summary>
+    /// The start of the time range in Unix time in seconds.
+    /// </summary>
+    public long? Start { get; init; }
+
+    /// <summary>
+    /// The end of the time range in Unix time in seconds.
+    /// </summary>
+    public long? End { get; init; }
+
+    /// <summary>
+    /// The number of items to return.
+    /// </summary>
+    public int? Limit { get; init; }
+
+    /// <summary>
+    /// The number of items to skip.
+    /// </summary>
+    [DefaultValue(0)]
+    public int Skip { get; init; }
+}
+
+public record AggregateClaimsQueryParameters
+{
+    /// <summary>
+    /// The size of each bucket in the aggregation
+    /// </summary>
+    public required TimeAggregate TimeAggregate { get; init; }
+
+    /// <summary>
+    /// The time zone. See https://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a list of valid time zones.
+    /// </summary>
+    public required string TimeZone { get; init; }
+
+    /// <summary>
+    /// The start of the time range in Unix time in seconds.
+    /// </summary>
+    public long? Start { get; init; }
+
+    /// <summary>
+    /// The end of the time range in Unix time in seconds.
+    /// </summary>
+    public long? End { get; init; }
+
+    /// <summary>
+    /// The number of items to return.
+    /// </summary>
+    public int? Limit { get; init; }
+
+    /// <summary>
+    /// The number of items to skip.
+    /// </summary>
+    [DefaultValue(0)]
+    public int Skip { get; init; }
+}
+
 /// <summary>
 /// A claim record representing a claim of a production and consumption certificate.
 /// </summary>