diff --git a/src/lib/components/JSONEditor.svelte b/src/lib/components/JSONEditor.svelte
index 98b4fb27..a51e270d 100644
--- a/src/lib/components/JSONEditor.svelte
+++ b/src/lib/components/JSONEditor.svelte
@@ -9,7 +9,7 @@
   import AbsolutePopup from './modals/popup/AbsolutePopup.svelte'
   import CodeMode from './modes/codemode/CodeMode.svelte'
   import TreeMode from './modes/treemode/TreeMode.svelte'
-  import { javascriptQueryLanguage } from '../plugins/query/javascriptQueryLanguage.ts'
+  import { javascriptQueryLanguage } from '../plugins/query/javascriptQueryLanguage.js'
   import { renderValue } from '$lib/plugins/value/renderValue'
   import { tick } from 'svelte'
   import TransformModal from './modals/TransformModal.svelte'
diff --git a/src/lib/components/modals/SortModal.svelte b/src/lib/components/modals/SortModal.svelte
index e3a1fbdf..4b8a4db9 100644
--- a/src/lib/components/modals/SortModal.svelte
+++ b/src/lib/components/modals/SortModal.svelte
@@ -5,13 +5,13 @@
   import { getContext } from 'svelte'
   import Select from 'svelte-select'
   import Header from './Header.svelte'
-  import { getNestedPaths } from '../../utils/arrayUtils.ts'
-  import { isObject } from '../../utils/typeUtils.ts'
+  import { getNestedPaths } from '../../utils/arrayUtils.js'
+  import { isObject } from '../../utils/typeUtils.js'
   import { stringifyPath } from '../../utils/pathUtils.js'
   import { sortArray, sortObjectKeys } from '../../logic/sort.js'
   import { sortModalState } from './sortModalState.js'
   import { compileJSONPointer, getIn } from 'immutable-json-patch'
-  import { createDebug } from '$lib/utils/debug.js'
+  import { createDebug } from '$lib/utils/debug'
 
   const debug = createDebug('jsoneditor:SortModal')
 
diff --git a/src/lib/components/modals/TransformWizard.svelte b/src/lib/components/modals/TransformWizard.svelte
index f57b1ab1..ea0afaa9 100644
--- a/src/lib/components/modals/TransformWizard.svelte
+++ b/src/lib/components/modals/TransformWizard.svelte
@@ -2,11 +2,11 @@
 
 <script>
   import Select from 'svelte-select'
-  import { getNestedPaths } from '../../utils/arrayUtils.ts'
   import { stringifyPath } from '../../utils/pathUtils.js'
   import { createDebug } from '../../utils/debug.js'
   import { isEmpty, isEqual } from 'lodash-es'
   import { setIn } from 'immutable-json-patch'
+  import { getNestedPaths } from '../../utils/arrayUtils.js'
 
   const debug = createDebug('jsoneditor:TransformWizard')
 
diff --git a/src/lib/components/modals/repair/JSONRepairComponent.svelte b/src/lib/components/modals/repair/JSONRepairComponent.svelte
index aaa29f95..92dc71d4 100644
--- a/src/lib/components/modals/repair/JSONRepairComponent.svelte
+++ b/src/lib/components/modals/repair/JSONRepairComponent.svelte
@@ -12,7 +12,7 @@
   import Message from '../../controls/Message.svelte'
   import { onDestroy, onMount } from 'svelte'
   import { activeElementIsChildOf, getWindow } from '../../../utils/domUtils'
-  import { normalizeJsonParseError } from '../../../utils/jsonUtils.ts'
+  import { normalizeJsonParseError } from '../../../utils/jsonUtils.js'
   import { createFocusTracker } from '../../controls/createFocusTracker.js'
   import Menu from '../../controls/Menu.svelte'
   import { noop } from 'lodash-es'
diff --git a/src/lib/components/modes/codemode/CodeMode.svelte b/src/lib/components/modes/codemode/CodeMode.svelte
index 9d738bb0..2cf2f192 100644
--- a/src/lib/components/modes/codemode/CodeMode.svelte
+++ b/src/lib/components/modes/codemode/CodeMode.svelte
@@ -36,7 +36,7 @@
   import { Compartment } from '@codemirror/state'
   import { closeSearchPanel, openSearchPanel, search } from '@codemirror/search'
   import { redo, redoDepth, undo, undoDepth } from '@codemirror/history'
-  import { normalizeJsonParseError } from '../../../utils/jsonUtils.ts'
+  import { normalizeJsonParseError } from '../../../utils/jsonUtils.js'
   import { MAX_VALIDATABLE_SIZE } from '../../../constants.js'
   import { measure } from '../../../utils/timeUtils.js'
   import jsonSourceMap from 'json-source-map'
diff --git a/src/lib/components/modes/treemode/JSONNode.svelte b/src/lib/components/modes/treemode/JSONNode.svelte
index 203169e2..702d08d5 100644
--- a/src/lib/components/modes/treemode/JSONNode.svelte
+++ b/src/lib/components/modes/treemode/JSONNode.svelte
@@ -41,7 +41,7 @@
   import { createDebug } from '$lib/utils/debug'
   import { forEachKey } from '../../../logic/documentState.js'
   import { onMoveSelection } from '../../../logic/dragging.js'
-  import { forEachIndex } from '../../../utils/arrayUtils.ts'
+  import { forEachIndex } from '../../../utils/arrayUtils.js'
   import { getDataPathFromTarget } from '../../../utils/domUtils'
   import { createMemoizePath } from '../../../utils/pathUtils.js'
   import { keyIsSelected } from '../../../logic/selection.js'
diff --git a/src/lib/components/modes/treemode/TreeMode.svelte b/src/lib/components/modes/treemode/TreeMode.svelte
index c5fdba78..b07861d6 100644
--- a/src/lib/components/modes/treemode/TreeMode.svelte
+++ b/src/lib/components/modes/treemode/TreeMode.svelte
@@ -89,7 +89,7 @@
   import Welcome from './Welcome.svelte'
   import NavigationBar from '../../../components/controls/navigationBar/NavigationBar.svelte'
   import SearchBox from '../../../components/modes/treemode/menu/SearchBox.svelte'
-  import { convertValue, isLargeContent } from '../../../utils/jsonUtils.ts'
+  import { convertValue, isLargeContent } from '../../../utils/jsonUtils.js'
   import { MAX_DOCUMENT_SIZE_EXPAND_ALL } from '../../../constants.js'
   import { canConvert, createSelectionFromOperations } from '../../../logic/selection.js'
   import { collapse, expandWithCallback } from '../../../logic/documentState.js'
diff --git a/src/lib/components/modes/treemode/contextmenu/ContextMenu.svelte b/src/lib/components/modes/treemode/contextmenu/ContextMenu.svelte
index 4abdce6f..8287e1e7 100644
--- a/src/lib/components/modes/treemode/contextmenu/ContextMenu.svelte
+++ b/src/lib/components/modes/treemode/contextmenu/ContextMenu.svelte
@@ -21,10 +21,9 @@
   import DropdownButton from '../../../../components/controls/DropdownButton.svelte'
   import { SELECTION_TYPE } from '$lib/logic/selection'
   import { keyComboFromEvent } from '$lib/utils/keyBindings'
-  import { isObjectOrArray } from '$lib/utils/typeUtils'
+  import { isObject, isObjectOrArray } from '$lib/utils/typeUtils.js'
   import { faCheckSquare, faLightbulb, faSquare } from '@fortawesome/free-regular-svg-icons'
   import { STATE_ENFORCE_STRING } from '$lib/constants'
-  import { isObject } from '../../../../utils/typeUtils.ts'
   import { canConvert, singleItemSelected } from '../../../../logic/selection.js'
   import { findNearestElement } from '../../../../utils/domUtils'
 
diff --git a/src/lib/index.js b/src/lib/index.js
index 20c38447..b5c31e83 100644
--- a/src/lib/index.js
+++ b/src/lib/index.js
@@ -11,7 +11,7 @@ import _TimestampTag from './plugins/value/components/TimestampTag.svelte'
 export const JSONEditor = _JSONEditor
 
 // value plugins
-export { renderValue } from './plugins/value/renderValue.ts'
+export { renderValue } from './plugins/value/renderValue.js'
 export { renderJSONSchemaEnum } from './plugins/value/renderJSONSchemaEnum.js'
 export const BooleanToggle = _BooleanToggle
 export const ColorPicker = _ColorPicker
@@ -21,19 +21,19 @@ export const ReadonlyValue = _ReadonlyValue
 export const TimestampTag = _TimestampTag
 
 // validator plugins
-export { createAjvValidator } from './plugins/validator/createAjvValidator.ts'
+export { createAjvValidator } from './plugins/validator/createAjvValidator.js'
 
 // query plugins
-export { lodashQueryLanguage } from './plugins/query/lodashQueryLanguage.ts'
-export { javascriptQueryLanguage } from './plugins/query/javascriptQueryLanguage.ts'
-export { jmespathQueryLanguage } from './plugins/query/jmespathQueryLanguage.ts'
+export { lodashQueryLanguage } from './plugins/query/lodashQueryLanguage.js'
+export { javascriptQueryLanguage } from './plugins/query/javascriptQueryLanguage.js'
+export { jmespathQueryLanguage } from './plugins/query/jmespathQueryLanguage.js'
 
 // utils
 export const SortModal = _SortModal
 export const TransformModal = _TransformModal
 export { getJSONSchemaOptions, findSchema, findEnum } from './utils/jsonSchemaUtils.js'
 export { parseJSONPointerWithArrayIndices } from './utils/jsonPointer.js'
-export { isTextContent, isLargeContent, estimateSerializedSize } from './utils/jsonUtils.ts'
+export { isTextContent, isLargeContent, estimateSerializedSize } from './utils/jsonUtils'
 export {
   parseJSONPointer,
   compileJSONPointer,
diff --git a/src/lib/logic/documentState.js b/src/lib/logic/documentState.js
index 0f75f393..818025c9 100644
--- a/src/lib/logic/documentState.js
+++ b/src/lib/logic/documentState.js
@@ -15,9 +15,9 @@ import {
   STATE_KEYS,
   STATE_VISIBLE_SECTIONS
 } from '../constants.js'
-import { forEachIndex } from '../utils/arrayUtils.ts'
+import { forEachIndex } from '../utils/arrayUtils.js'
 import { parseJSONPointerWithArrayIndices } from '../utils/jsonPointer.js'
-import { isObject, isStringContainingPrimitiveValue } from '../utils/typeUtils.ts'
+import { isObject, isStringContainingPrimitiveValue } from '../utils/typeUtils.js'
 import {
   currentRoundNumber,
   inVisibleSection,
diff --git a/src/lib/logic/documentState.test.js b/src/lib/logic/documentState.test.js
index 5b3f5f43..f7436f8e 100644
--- a/src/lib/logic/documentState.test.js
+++ b/src/lib/logic/documentState.test.js
@@ -9,7 +9,7 @@ import {
   STATE_KEYS,
   STATE_VISIBLE_SECTIONS
 } from '../constants.js'
-import { isObject } from '../utils/typeUtils.ts'
+import { isObject } from '../utils/typeUtils.js'
 import {
   CARET_POSITION,
   collapseSinglePath,
diff --git a/src/lib/logic/operations.js b/src/lib/logic/operations.js
index f102ad80..a83df82e 100644
--- a/src/lib/logic/operations.js
+++ b/src/lib/logic/operations.js
@@ -1,8 +1,8 @@
 import { cloneDeepWith, first, initial, isEmpty, last, times } from 'lodash-es'
 import { compileJSONPointer, getIn } from 'immutable-json-patch'
-import { parseAndRepair, parseAndRepairOrUndefined, parsePartialJson } from '../utils/jsonUtils.ts'
+import { parseAndRepair, parseAndRepairOrUndefined, parsePartialJson } from '../utils/jsonUtils.js'
 import { findUniqueName } from '../utils/stringUtils.js'
-import { isObject, isObjectOrArray } from '../utils/typeUtils.ts'
+import { isObject, isObjectOrArray } from '../utils/typeUtils.js'
 import { getKeys, getNextKeys } from './documentState.js'
 import {
   createSelection,
diff --git a/src/lib/logic/search.js b/src/lib/logic/search.js
index 432ea243..11c924c5 100644
--- a/src/lib/logic/search.js
+++ b/src/lib/logic/search.js
@@ -9,7 +9,7 @@ import {
 import { getKeys } from './documentState.js'
 import { createSelectionFromOperations } from './selection.js'
 import { rename } from './operations.js'
-import { stringConvert } from '../utils/typeUtils.ts'
+import { stringConvert } from '../utils/typeUtils.js'
 
 // TODO: comment
 export function updateSearchResult(json, flatResults, previousResult) {
diff --git a/src/lib/logic/selection.js b/src/lib/logic/selection.js
index e8303e94..924c2f9d 100644
--- a/src/lib/logic/selection.js
+++ b/src/lib/logic/selection.js
@@ -2,7 +2,7 @@ import { compileJSONPointer, existsIn, getIn, setIn } from 'immutable-json-patch
 import { first, initial, isEmpty, isEqual, last } from 'lodash-es'
 import { STATE_EXPANDED, STATE_KEYS, STATE_SELECTION } from '../constants.js'
 import { parseJSONPointerWithArrayIndices } from '../utils/jsonPointer.js'
-import { isObject, isObjectOrArray } from '../utils/typeUtils.ts'
+import { isObject, isObjectOrArray } from '../utils/typeUtils.js'
 import {
   getNextVisiblePath,
   getPreviousVisiblePath,