diff --git a/apps/api/src/app/core/current-rate.service.ts b/apps/api/src/app/core/current-rate.service.ts
index 23996796e..4ca9ff819 100644
--- a/apps/api/src/app/core/current-rate.service.ts
+++ b/apps/api/src/app/core/current-rate.service.ts
@@ -1,6 +1,6 @@
-import { GetValueObject } from '@ghostfolio/api/app/core/get-value-object.interface';
-import { GetValueParams } from '@ghostfolio/api/app/core/get-value-params.interface';
-import { GetValuesParams } from '@ghostfolio/api/app/core/get-values-params.interface';
+import { GetValueObject } from '@ghostfolio/api/app/core/interfaces/get-value-object.interface';
+import { GetValueParams } from '@ghostfolio/api/app/core/interfaces/get-value-params.interface';
+import { GetValuesParams } from '@ghostfolio/api/app/core/interfaces/get-values-params.interface';
 import { DataProviderService } from '@ghostfolio/api/services/data-provider.service';
 import { ExchangeRateDataService } from '@ghostfolio/api/services/exchange-rate-data.service';
 import { resetHours } from '@ghostfolio/common/helper';
diff --git a/apps/api/src/app/core/date-query.interface.ts b/apps/api/src/app/core/interfaces/date-query.interface.ts
similarity index 100%
rename from apps/api/src/app/core/date-query.interface.ts
rename to apps/api/src/app/core/interfaces/date-query.interface.ts
diff --git a/apps/api/src/app/core/get-value-object.interface.ts b/apps/api/src/app/core/interfaces/get-value-object.interface.ts
similarity index 100%
rename from apps/api/src/app/core/get-value-object.interface.ts
rename to apps/api/src/app/core/interfaces/get-value-object.interface.ts
diff --git a/apps/api/src/app/core/get-value-params.interface.ts b/apps/api/src/app/core/interfaces/get-value-params.interface.ts
similarity index 100%
rename from apps/api/src/app/core/get-value-params.interface.ts
rename to apps/api/src/app/core/interfaces/get-value-params.interface.ts
diff --git a/apps/api/src/app/core/get-values-params.interface.ts b/apps/api/src/app/core/interfaces/get-values-params.interface.ts
similarity index 69%
rename from apps/api/src/app/core/get-values-params.interface.ts
rename to apps/api/src/app/core/interfaces/get-values-params.interface.ts
index b09d26af9..9f1338000 100644
--- a/apps/api/src/app/core/get-values-params.interface.ts
+++ b/apps/api/src/app/core/interfaces/get-values-params.interface.ts
@@ -1,4 +1,4 @@
-import { DateQuery } from '@ghostfolio/api/app/core/date-query.interface';
+import { DateQuery } from '@ghostfolio/api/app/core/interfaces/date-query.interface';
 import { Currency } from '@prisma/client';
 
 export interface GetValuesParams {
diff --git a/apps/api/src/app/core/portfolio-order.ts b/apps/api/src/app/core/interfaces/portfolio-order.interface.ts
similarity index 100%
rename from apps/api/src/app/core/portfolio-order.ts
rename to apps/api/src/app/core/interfaces/portfolio-order.interface.ts
diff --git a/apps/api/src/app/core/timeline-period.ts b/apps/api/src/app/core/interfaces/timeline-period.interface.ts
similarity index 100%
rename from apps/api/src/app/core/timeline-period.ts
rename to apps/api/src/app/core/interfaces/timeline-period.interface.ts
diff --git a/apps/api/src/app/core/timeline-specification.ts b/apps/api/src/app/core/interfaces/timeline-specification.interface.ts
similarity index 100%
rename from apps/api/src/app/core/timeline-specification.ts
rename to apps/api/src/app/core/interfaces/timeline-specification.interface.ts
index 78687f0fe..26228a1fa 100644
--- a/apps/api/src/app/core/timeline-specification.ts
+++ b/apps/api/src/app/core/interfaces/timeline-specification.interface.ts
@@ -1,6 +1,6 @@
 export type Accuracy = 'year' | 'month' | 'day';
 
 export interface TimelineSpecification {
-  start: string;
   accuracy: Accuracy;
+  start: string;
 }
diff --git a/apps/api/src/app/core/transaction-point-symbol.ts b/apps/api/src/app/core/interfaces/transaction-point-symbol.interface.ts
similarity index 100%
rename from apps/api/src/app/core/transaction-point-symbol.ts
rename to apps/api/src/app/core/interfaces/transaction-point-symbol.interface.ts
diff --git a/apps/api/src/app/core/transaction-point.ts b/apps/api/src/app/core/interfaces/transaction-point.interface.ts
similarity index 75%
rename from apps/api/src/app/core/transaction-point.ts
rename to apps/api/src/app/core/interfaces/transaction-point.interface.ts
index 815f40b4a..eadc1e63f 100644
--- a/apps/api/src/app/core/transaction-point.ts
+++ b/apps/api/src/app/core/interfaces/transaction-point.interface.ts
@@ -1,4 +1,4 @@
-import { TransactionPointSymbol } from '@ghostfolio/api/app/core/transaction-point-symbol';
+import { TransactionPointSymbol } from '@ghostfolio/api/app/core/interfaces/transaction-point-symbol.interface';
 
 export interface TransactionPoint {
   date: string;
diff --git a/apps/api/src/app/core/market-data.service.ts b/apps/api/src/app/core/market-data.service.ts
index e493b2aa7..b84c31632 100644
--- a/apps/api/src/app/core/market-data.service.ts
+++ b/apps/api/src/app/core/market-data.service.ts
@@ -2,7 +2,7 @@ import { PrismaService } from '@ghostfolio/api/services/prisma.service';
 import { resetHours } from '@ghostfolio/common/helper';
 import { Injectable } from '@nestjs/common';
 import { MarketData } from '@prisma/client';
-import { DateQuery } from './date-query.interface';
+import { DateQuery } from './interfaces/date-query.interface';
 
 @Injectable()
 export class MarketDataService {
diff --git a/apps/api/src/app/core/portfolio-calculator.spec.ts b/apps/api/src/app/core/portfolio-calculator.spec.ts
index 9e0675fd9..47cae8b5d 100644
--- a/apps/api/src/app/core/portfolio-calculator.spec.ts
+++ b/apps/api/src/app/core/portfolio-calculator.spec.ts
@@ -1,11 +1,11 @@
 import { CurrentRateService } from '@ghostfolio/api/app/core/current-rate.service';
-import { GetValueParams } from '@ghostfolio/api/app/core/get-value-params.interface';
-import { GetValuesParams } from '@ghostfolio/api/app/core/get-values-params.interface';
+import { GetValueParams } from '@ghostfolio/api/app/core/interfaces/get-value-params.interface';
+import { GetValuesParams } from '@ghostfolio/api/app/core/interfaces/get-values-params.interface';
 import { PortfolioCalculator } from '@ghostfolio/api/app/core/portfolio-calculator';
-import { PortfolioOrder } from '@ghostfolio/api/app/core/portfolio-order';
-import { TimelinePeriod } from '@ghostfolio/api/app/core/timeline-period';
-import { TimelineSpecification } from '@ghostfolio/api/app/core/timeline-specification';
-import { TransactionPoint } from '@ghostfolio/api/app/core/transaction-point';
+import { PortfolioOrder } from '@ghostfolio/api/app/core/interfaces/portfolio-order.interface';
+import { TimelinePeriod } from '@ghostfolio/api/app/core/interfaces/timeline-period.interface';
+import { TimelineSpecification } from '@ghostfolio/api/app/core/interfaces/timeline-specification.interface';
+import { TransactionPoint } from '@ghostfolio/api/app/core/interfaces/transaction-point.interface';
 import { OrderType } from '@ghostfolio/api/models/order-type';
 import { resetHours } from '@ghostfolio/common/helper';
 import { Currency } from '@prisma/client';
diff --git a/apps/api/src/app/core/portfolio-calculator.ts b/apps/api/src/app/core/portfolio-calculator.ts
index d68bf4bfb..3a4421988 100644
--- a/apps/api/src/app/core/portfolio-calculator.ts
+++ b/apps/api/src/app/core/portfolio-calculator.ts
@@ -1,13 +1,13 @@
 import { CurrentRateService } from '@ghostfolio/api/app/core/current-rate.service';
-import { GetValueObject } from '@ghostfolio/api/app/core/get-value-object.interface';
-import { PortfolioOrder } from '@ghostfolio/api/app/core/portfolio-order';
-import { TimelinePeriod } from '@ghostfolio/api/app/core/timeline-period';
+import { GetValueObject } from '@ghostfolio/api/app/core/interfaces/get-value-object.interface';
+import { PortfolioOrder } from '@ghostfolio/api/app/core/interfaces/portfolio-order.interface';
+import { TimelinePeriod } from '@ghostfolio/api/app/core/interfaces/timeline-period.interface';
 import {
   Accuracy,
   TimelineSpecification
-} from '@ghostfolio/api/app/core/timeline-specification';
-import { TransactionPoint } from '@ghostfolio/api/app/core/transaction-point';
-import { TransactionPointSymbol } from '@ghostfolio/api/app/core/transaction-point-symbol';
+} from '@ghostfolio/api/app/core/interfaces/timeline-specification.interface';
+import { TransactionPoint } from '@ghostfolio/api/app/core/interfaces/transaction-point.interface';
+import { TransactionPointSymbol } from '@ghostfolio/api/app/core/interfaces/transaction-point-symbol.interface';
 import { OrderType } from '@ghostfolio/api/models/order-type';
 import { DATE_FORMAT, parseDate, resetHours } from '@ghostfolio/common/helper';
 import { TimelinePosition } from '@ghostfolio/common/interfaces';
diff --git a/apps/api/src/app/portfolio/portfolio.service.ts b/apps/api/src/app/portfolio/portfolio.service.ts
index dc6684843..b2df36924 100644
--- a/apps/api/src/app/portfolio/portfolio.service.ts
+++ b/apps/api/src/app/portfolio/portfolio.service.ts
@@ -1,8 +1,8 @@
 import { AccountService } from '@ghostfolio/api/app/account/account.service';
 import { CurrentRateService } from '@ghostfolio/api/app/core/current-rate.service';
 import { PortfolioCalculator } from '@ghostfolio/api/app/core/portfolio-calculator';
-import { PortfolioOrder } from '@ghostfolio/api/app/core/portfolio-order';
-import { TimelineSpecification } from '@ghostfolio/api/app/core/timeline-specification';
+import { PortfolioOrder } from '@ghostfolio/api/app/core/interfaces/portfolio-order.interface';
+import { TimelineSpecification } from '@ghostfolio/api/app/core/interfaces/timeline-specification.interface';
 import { OrderService } from '@ghostfolio/api/app/order/order.service';
 import { RedisCacheService } from '@ghostfolio/api/app/redis-cache/redis-cache.service';
 import { UserService } from '@ghostfolio/api/app/user/user.service';