diff --git a/backend/src/auth/auth-token.dto.ts b/backend/src/auth/auth-token.dto.ts
index 07859dd9a..d86d31ad6 100644
--- a/backend/src/auth/auth-token.dto.ts
+++ b/backend/src/auth/auth-token.dto.ts
@@ -40,5 +40,6 @@ export class AuthTokenCreateDto extends BaseDto {
   label: string;
 
   @IsNumber()
+  @Type(() => Number)
   validUntil: TimestampMillis;
 }
diff --git a/backend/src/auth/auth.module.ts b/backend/src/auth/auth.module.ts
index d47d6a812..874805b5a 100644
--- a/backend/src/auth/auth.module.ts
+++ b/backend/src/auth/auth.module.ts
@@ -11,7 +11,8 @@ import { LoggerModule } from '../logger/logger.module';
 import { UsersModule } from '../users/users.module';
 import { AuthToken } from './auth-token.entity';
 import { AuthService } from './auth.service';
-import { TokenStrategy } from './token.strategy';
+import { MockAuthGuard } from './mock-auth.guard';
+import { TokenAuthGuard, TokenStrategy } from './token.strategy';
 
 @Module({
   imports: [
@@ -20,7 +21,7 @@ import { TokenStrategy } from './token.strategy';
     LoggerModule,
     TypeOrmModule.forFeature([AuthToken]),
   ],
-  providers: [AuthService, TokenStrategy],
+  providers: [AuthService, TokenStrategy, MockAuthGuard, TokenAuthGuard],
   exports: [AuthService],
 })
 export class AuthModule {}
diff --git a/backend/src/frontend-config/frontend-config.dto.ts b/backend/src/frontend-config/frontend-config.dto.ts
index 223af14f3..3cfe29b5c 100644
--- a/backend/src/frontend-config/frontend-config.dto.ts
+++ b/backend/src/frontend-config/frontend-config.dto.ts
@@ -3,6 +3,7 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import { Type } from 'class-transformer';
 import {
   IsArray,
   IsBoolean,
@@ -50,6 +51,7 @@ export class AuthProviderWithoutCustomNameDto extends BaseDto {
    * The type of the auth provider.
    */
   @IsString()
+  @Type(() => String)
   type: AuthProviderTypeWithoutCustomName;
 }
 
@@ -58,6 +60,7 @@ export class AuthProviderWithCustomNameDto extends BaseDto {
    * The type of the auth provider.
    */
   @IsString()
+  @Type(() => String)
   type: AuthProviderTypeWithCustomName;
 
   /**
@@ -94,6 +97,7 @@ export class BrandingDto extends BaseDto {
    */
   @IsUrl()
   @IsOptional()
+  @Type(() => URL)
   logo?: URL;
 }
 
@@ -104,6 +108,7 @@ export class SpecialUrlsDto extends BaseDto {
    */
   @IsUrl()
   @IsOptional()
+  @Type(() => URL)
   privacy?: URL;
 
   /**
@@ -112,6 +117,7 @@ export class SpecialUrlsDto extends BaseDto {
    */
   @IsUrl()
   @IsOptional()
+  @Type(() => URL)
   termsOfUse?: URL;
 
   /**
@@ -120,6 +126,7 @@ export class SpecialUrlsDto extends BaseDto {
    */
   @IsUrl()
   @IsOptional()
+  @Type(() => URL)
   imprint?: URL;
 }
 
@@ -139,6 +146,7 @@ export class FrontendConfigDto extends BaseDto {
   /**
    * Which auth providers are enabled and how are they configured?
    */
+  // eslint-disable-next-line @darraghor/nestjs-typed/validated-non-primitive-property-needs-type-decorator
   @IsArray()
   @ValidateNested({ each: true })
   authProviders: AuthProviderDto[];
@@ -147,6 +155,7 @@ export class FrontendConfigDto extends BaseDto {
    * Individual branding information
    */
   @ValidateNested()
+  @Type(() => BrandingDto)
   branding: BrandingDto;
 
   /**
@@ -159,12 +168,14 @@ export class FrontendConfigDto extends BaseDto {
    * Links to some special pages
    */
   @ValidateNested()
+  @Type(() => SpecialUrlsDto)
   specialUrls: SpecialUrlsDto;
 
   /**
    * The version of HedgeDoc
    */
   @ValidateNested()
+  @Type(() => ServerVersion)
   version: ServerVersion;
 
   /**
@@ -172,6 +183,7 @@ export class FrontendConfigDto extends BaseDto {
    */
   @IsUrl()
   @IsOptional()
+  @Type(() => URL)
   plantUmlServer?: URL;
 
   /**
diff --git a/backend/src/history/history-entry.dto.ts b/backend/src/history/history-entry.dto.ts
index 9f75ba9f5..eaf2e1b5a 100644
--- a/backend/src/history/history-entry.dto.ts
+++ b/backend/src/history/history-entry.dto.ts
@@ -37,7 +37,7 @@ export class HistoryEntryDto extends BaseDto {
 
   @IsArray()
   @IsString({ each: true })
-  @ApiProperty()
+  @ApiProperty({ isArray: true, type: String })
   tags: string[];
 
   /**
diff --git a/backend/src/identity/identity.module.ts b/backend/src/identity/identity.module.ts
index dfbf9bb68..57794f4ce 100644
--- a/backend/src/identity/identity.module.ts
+++ b/backend/src/identity/identity.module.ts
@@ -12,8 +12,8 @@ import { User } from '../users/user.entity';
 import { UsersModule } from '../users/users.module';
 import { Identity } from './identity.entity';
 import { IdentityService } from './identity.service';
-import { LdapStrategy } from './ldap/ldap.strategy';
-import { LocalStrategy } from './local/local.strategy';
+import { LdapAuthGuard, LdapStrategy } from './ldap/ldap.strategy';
+import { LocalAuthGuard, LocalStrategy } from './local/local.strategy';
 
 @Module({
   imports: [
@@ -23,7 +23,13 @@ import { LocalStrategy } from './local/local.strategy';
     LoggerModule,
   ],
   controllers: [],
-  providers: [IdentityService, LocalStrategy, LdapStrategy],
+  providers: [
+    IdentityService,
+    LocalStrategy,
+    LdapStrategy,
+    LdapAuthGuard,
+    LocalAuthGuard,
+  ],
   exports: [IdentityService, LocalStrategy, LdapStrategy],
 })
 export class IdentityModule {}
diff --git a/backend/src/identity/local/login.dto.ts b/backend/src/identity/local/login.dto.ts
index 2e4d91a88..7ec9af2a7 100644
--- a/backend/src/identity/local/login.dto.ts
+++ b/backend/src/identity/local/login.dto.ts
@@ -3,11 +3,13 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import { Type } from 'class-transformer';
 import { IsLowercase, IsString } from 'class-validator';
 
 import { Username } from '../../utils/username';
 
 export class LoginDto {
+  @Type(() => String)
   @IsString()
   @IsLowercase()
   username: Username;
diff --git a/backend/src/identity/local/register.dto.ts b/backend/src/identity/local/register.dto.ts
index 54bc61cf9..7a375b8c0 100644
--- a/backend/src/identity/local/register.dto.ts
+++ b/backend/src/identity/local/register.dto.ts
@@ -3,11 +3,13 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import { Type } from 'class-transformer';
 import { IsLowercase, IsString } from 'class-validator';
 
 import { Username } from '../../utils/username';
 
 export class RegisterDto {
+  @Type(() => String)
   @IsString()
   @IsLowercase()
   username: Username;
diff --git a/backend/src/media/media-upload.dto.ts b/backend/src/media/media-upload.dto.ts
index bb4044920..f625bae19 100644
--- a/backend/src/media/media-upload.dto.ts
+++ b/backend/src/media/media-upload.dto.ts
@@ -43,6 +43,7 @@ export class MediaUploadDto extends BaseDto {
    */
   @IsString()
   @IsLowercase()
+  @IsOptional()
   @ApiProperty()
   username: Username | null;
 }
diff --git a/backend/src/monitoring/server-status.dto.ts b/backend/src/monitoring/server-status.dto.ts
index a4fd7a3a0..af20ec836 100644
--- a/backend/src/monitoring/server-status.dto.ts
+++ b/backend/src/monitoring/server-status.dto.ts
@@ -3,7 +3,7 @@
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
-import { ApiProperty } from '@nestjs/swagger';
+import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
 
 import { BaseDto } from '../utils/base.dto.';
 
@@ -14,9 +14,9 @@ export class ServerVersion {
   minor: number;
   @ApiProperty()
   patch: number;
-  @ApiProperty()
+  @ApiPropertyOptional()
   preRelease?: string;
-  @ApiProperty()
+  @ApiPropertyOptional()
   commit?: string;
   @ApiProperty()
   fullString: string;
diff --git a/backend/src/notes/note-metadata.dto.ts b/backend/src/notes/note-metadata.dto.ts
index deeef526b..cbb6a5e78 100644
--- a/backend/src/notes/note-metadata.dto.ts
+++ b/backend/src/notes/note-metadata.dto.ts
@@ -29,9 +29,10 @@ export class NoteMetadataDto extends BaseDto {
   /**
    * All aliases of the note (including the primaryAlias)
    */
+  @Type(() => AliasDto)
   @IsArray()
-  @ValidateNested()
-  @ApiProperty()
+  @ValidateNested({ each: true })
+  @ApiProperty({ isArray: true, type: AliasDto })
   aliases: AliasDto[];
 
   /**
@@ -67,7 +68,7 @@ export class NoteMetadataDto extends BaseDto {
    */
   @IsArray()
   @IsString({ each: true })
-  @ApiProperty()
+  @ApiProperty({ isArray: true, type: String })
   tags: string[];
 
   @IsNumber()
@@ -86,8 +87,9 @@ export class NoteMetadataDto extends BaseDto {
   /**
    * User that last edited the note
    */
-  @IsString()
+  // eslint-disable-next-line @darraghor/nestjs-typed/api-property-matches-property-optionality
   @ApiPropertyOptional()
+  @IsString()
   @IsOptional()
   updateUsername: string | null;
 
@@ -114,13 +116,13 @@ export class NoteMetadataDto extends BaseDto {
    */
   @IsArray()
   @IsString({ each: true })
-  @ApiProperty()
+  @ApiProperty({ isArray: true, type: String })
   editedBy: string[];
 
   /**
    * Permissions currently in effect for the note
    */
-  @ValidateNested({ each: true })
+  @ValidateNested()
   @Type(() => NotePermissionsDto)
   @ApiProperty({ type: NotePermissionsDto })
   permissions: NotePermissionsDto;
@@ -151,6 +153,6 @@ export class NoteMetadataUpdateDto {
    */
   @IsArray()
   @IsString({ each: true })
-  @ApiProperty()
+  @ApiProperty({ isArray: true, type: String })
   tags: string[];
 }
diff --git a/backend/src/notes/note-permissions.dto.ts b/backend/src/notes/note-permissions.dto.ts
index 30372010e..b462d79df 100644
--- a/backend/src/notes/note-permissions.dto.ts
+++ b/backend/src/notes/note-permissions.dto.ts
@@ -21,6 +21,7 @@ export class NoteUserPermissionEntryDto extends BaseDto {
   /**
    * Username of the User this permission applies to
    */
+  @Type(() => String)
   @IsString()
   @IsLowercase()
   @ApiProperty()
@@ -40,6 +41,7 @@ export class NoteUserPermissionUpdateDto {
    * Username of the user this permission should apply to
    * @example "john.smith"
    */
+  @Type(() => String)
   @IsString()
   @IsLowercase()
   @ApiProperty()
@@ -93,6 +95,9 @@ export class NotePermissionsDto {
   /**
    * Username of the User this permission applies to
    */
+  // nestjs-typed does not detect '| null' types as optional
+  // eslint-disable-next-line @darraghor/nestjs-typed/api-property-matches-property-optionality
+  @Type(() => String)
   @IsString()
   @ApiPropertyOptional()
   @IsOptional()
diff --git a/backend/src/notes/note.dto.ts b/backend/src/notes/note.dto.ts
index ddba4d72e..deff740f4 100644
--- a/backend/src/notes/note.dto.ts
+++ b/backend/src/notes/note.dto.ts
@@ -23,6 +23,7 @@ export class NoteDto extends BaseDto {
   /**
    * Metadata of the note
    */
+  @Type(() => NoteMetadataDto)
   @ValidateNested()
   @ApiProperty({ type: NoteMetadataDto })
   metadata: NoteMetadataDto;
diff --git a/backend/src/revisions/edit.dto.ts b/backend/src/revisions/edit.dto.ts
index 156254a8c..fcc6facdf 100644
--- a/backend/src/revisions/edit.dto.ts
+++ b/backend/src/revisions/edit.dto.ts
@@ -16,6 +16,8 @@ export class EditDto extends BaseDto {
    * Is `null` if the user is anonymous
    * @example "john.smith"
    */
+  // nestjs-typed does not detect '| null' types as optional
+  // eslint-disable-next-line @darraghor/nestjs-typed/api-property-matches-property-optionality
   @IsString()
   @IsOptional()
   @ApiPropertyOptional()
diff --git a/backend/src/revisions/revision-metadata.dto.ts b/backend/src/revisions/revision-metadata.dto.ts
index 19b5a0f2f..347edf470 100644
--- a/backend/src/revisions/revision-metadata.dto.ts
+++ b/backend/src/revisions/revision-metadata.dto.ts
@@ -15,6 +15,7 @@ export class RevisionMetadataDto extends BaseDto {
    * ID of this revision
    * @example 13
    */
+  @Type(() => Number)
   @IsNumber()
   @ApiProperty()
   id: Revision['id'];
@@ -41,7 +42,7 @@ export class RevisionMetadataDto extends BaseDto {
    * Does not include anonymous users
    */
   @IsString()
-  @ApiProperty()
+  @ApiProperty({ isArray: true, type: String })
   authorUsernames: string[];
 
   /**
@@ -75,6 +76,6 @@ export class RevisionMetadataDto extends BaseDto {
    */
   @IsArray()
   @IsString({ each: true })
-  @ApiProperty()
+  @ApiProperty({ isArray: true, type: String })
   tags: string[];
 }
diff --git a/backend/src/revisions/revision.dto.ts b/backend/src/revisions/revision.dto.ts
index 1744230dd..53269b8be 100644
--- a/backend/src/revisions/revision.dto.ts
+++ b/backend/src/revisions/revision.dto.ts
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { ApiProperty } from '@nestjs/swagger';
+import { Type } from 'class-transformer';
 import { IsString, ValidateNested } from 'class-validator';
 
 import { EditDto } from './edit.dto';
@@ -28,7 +29,8 @@ export class RevisionDto extends RevisionMetadataDto {
   /**
    * All edit objects which are used in the revision.
    */
-  @ValidateNested()
-  @ApiProperty()
+  @Type(() => EditDto)
+  @ValidateNested({ each: true })
+  @ApiProperty({ isArray: true, type: EditDto })
   edits: EditDto[];
 }
diff --git a/backend/src/users/user-info.dto.ts b/backend/src/users/user-info.dto.ts
index d26937da8..af4b057bc 100644
--- a/backend/src/users/user-info.dto.ts
+++ b/backend/src/users/user-info.dto.ts
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 import { ApiProperty } from '@nestjs/swagger';
+import { Type } from 'class-transformer';
 import { IsLowercase, IsString } from 'class-validator';
 
 import { BaseDto } from '../utils/base.dto.';
@@ -14,6 +15,7 @@ export class UserInfoDto extends BaseDto {
    * The username
    * @example "john.smith"
    */
+  @Type(() => String)
   @IsString()
   @IsLowercase()
   @ApiProperty()