diff --git a/src/etapi/attachments.js b/src/etapi/attachments.js
index e39dee81f..6ea042db1 100644
--- a/src/etapi/attachments.js
+++ b/src/etapi/attachments.js
@@ -1,7 +1,7 @@
 const becca = require('../becca/becca');
 const eu = require('./etapi_utils');
 const mappers = require('./mappers');
-const v = require('./validators.js');
+const v = require('./validators');
 const utils = require('../services/utils');
 
 function register(router) {
diff --git a/src/etapi/attributes.js b/src/etapi/attributes.js
index db1c8f129..5a7fb1e53 100644
--- a/src/etapi/attributes.js
+++ b/src/etapi/attributes.js
@@ -2,7 +2,7 @@ const becca = require('../becca/becca');
 const eu = require('./etapi_utils');
 const mappers = require('./mappers');
 const attributeService = require('../services/attributes');
-const v = require('./validators.js');
+const v = require('./validators');
 
 function register(router) {
     eu.route(router, 'get', '/etapi/attributes/:attributeId', (req, res, next) => {
diff --git a/src/etapi/branches.js b/src/etapi/branches.js
index efd8b3ae9..9408b84e1 100644
--- a/src/etapi/branches.js
+++ b/src/etapi/branches.js
@@ -3,7 +3,7 @@ const eu = require('./etapi_utils');
 const mappers = require('./mappers');
 const BBranch = require('../becca/entities/bbranch');
 const entityChangesService = require('../services/entity_changes');
-const v = require('./validators.js');
+const v = require('./validators');
 
 function register(router) {
     eu.route(router, 'get', '/etapi/branches/:branchId', (req, res, next) => {
diff --git a/src/etapi/notes.js b/src/etapi/notes.js
index 101b9c55a..71485388e 100644
--- a/src/etapi/notes.js
+++ b/src/etapi/notes.js
@@ -4,7 +4,7 @@ const eu = require('./etapi_utils');
 const mappers = require('./mappers');
 const noteService = require('../services/notes');
 const TaskContext = require('../services/task_context');
-const v = require('./validators.js');
+const v = require('./validators');
 const searchService = require('../services/search/services/search');
 const SearchContext = require('../services/search/search_context');
 const zipExportService = require('../services/export/zip');
diff --git a/src/etapi/validators.js b/src/etapi/validators.ts
similarity index 64%
rename from src/etapi/validators.js
rename to src/etapi/validators.ts
index bcca288ca..7119a5319 100644
--- a/src/etapi/validators.js
+++ b/src/etapi/validators.ts
@@ -1,19 +1,19 @@
-const noteTypeService = require('../services/note_types');
-const dateUtils = require('../services/date_utils');
+import noteTypeService = require('../services/note_types');
+import dateUtils = require('../services/date_utils');
 
-function mandatory(obj) {
-    if (obj === undefined ) {
+function mandatory(obj: any | undefined) {
+    if (obj === undefined) {
         return `mandatory, but not set`;
     }
 }
 
-function notNull(obj) {
+function notNull(obj: any | null) {
     if (obj === null) {
         return `cannot be null`;
     }
 }
 
-function isString(obj) {
+function isString(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
@@ -23,23 +23,23 @@ function isString(obj) {
     }
 }
 
-function isLocalDateTime(obj) {
-    if (obj === undefined || obj === null) {
+function isLocalDateTime(obj: object | undefined | null) {
+    if (obj === undefined || obj === null || typeof obj !== "string") {
         return;
     }
 
     return dateUtils.validateLocalDateTime(obj);
 }
 
-function isUtcDateTime(obj) {
-    if (obj === undefined || obj === null) {
+function isUtcDateTime(obj: object | undefined | null) {
+    if (obj === undefined || obj === null || typeof obj !== "string") {
         return;
     }
 
     return dateUtils.validateUtcDateTime(obj);
 }
 
-function isBoolean(obj) {
+function isBoolean(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
@@ -49,7 +49,7 @@ function isBoolean(obj) {
     }
 }
 
-function isInteger(obj) {
+function isInteger(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
@@ -59,7 +59,7 @@ function isInteger(obj) {
     }
 }
 
-function isNoteId(obj) {
+function isNoteId(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
@@ -75,29 +75,29 @@ function isNoteId(obj) {
     }
 }
 
-function isNoteType(obj) {
+function isNoteType(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
 
     const noteTypes = noteTypeService.getNoteTypeNames();
 
-    if (!noteTypes.includes(obj)) {
+    if (typeof obj !== "string" || !noteTypes.includes(obj)) {
         return `'${obj}' is not a valid note type, allowed types are: ${noteTypes.join(", ")}`;
     }
 }
 
-function isAttributeType(obj) {
+function isAttributeType(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
 
-    if (!['label', 'relation'].includes(obj)) {
+    if (typeof obj !== "string" || !['label', 'relation'].includes(obj)) {
         return `'${obj}' is not a valid attribute type, allowed types are: label, relation`;
     }
 }
 
-function isValidEntityId(obj) {
+function isValidEntityId(obj: object | undefined | null) {
     if (obj === undefined || obj === null) {
         return;
     }
@@ -107,7 +107,7 @@ function isValidEntityId(obj) {
     }
 }
 
-module.exports = {
+export = {
     mandatory,
     notNull,
     isString,