Supported File Types (Strings)

.JSON - Chrome Messages (Strings)

File Extensions


API Extension






Plural forms support


Description support


Format options


Google provides internationalization support for Chrome extensions. Localized strings for Chrome extensions are stored in a .JSON file often named messages.json. Chrome JSON files have a slightly different structure than .JSON files used for localization on other platforms. For Chrome JSON, strings that need translation are placed in the sub-key message nested under each unit key-value pair. A description may also be added to each key-value pair.

Code Sample

  "boolean_key": {
    "message": "--- true\n"
  "empty_string_translation": {
    "message": ""
  "key_with_description": {
    "message": "Check it! Key has a description! (In some formats)",
    "description": "I'm a very important description for this key!"
  "key_with_line-break": {
    "message": "This translations contains\na line-break."
  "nested.deeply.key": {
    "message": "  I'm nested deeply."
  "nested.key": {
    "message": "This key is nested inside a namespace."
  "null_translation": {
    "message": null
  "": {
    "message": "Only one pluralization found."
  "pluralized_key.other": {
    "message": "Wow, you have %s pluralizations!"
  "": {
    "message": "You have no pluralization."
  "sample_collection": {
    "message": "---\n- first item\n- second item\n- third item\n"
  "simple_key": {
    "message": "I am a simple key with a simple message."
  "unverified_key": {
    "message": "Not yet verified waiting for it. (In some formats we also export this status)"

Plurals for JSON files

The most common format of plural key messages on various libraries:

"messages": {
    "one": "One message received.",
    "other": "%s messages received.",
    "zero": "No messages received."
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