diff --git a/packages/cozy-scripts/bin/cozy-scripts.js b/packages/cozy-scripts/bin/cozy-scripts.js
index 2e30cd2f3..945d6cf83 100755
--- a/packages/cozy-scripts/bin/cozy-scripts.js
+++ b/packages/cozy-scripts/bin/cozy-scripts.js
@@ -124,7 +124,8 @@ if (program.showConfig) {
     'test',
     'publish',
     'release',
-    'lint'
+    'lint',
+    'check-locales'
   ]
 
   if (availableScripts.includes(actionName)) {
diff --git a/packages/cozy-scripts/scripts/check-locales.js b/packages/cozy-scripts/scripts/check-locales.js
new file mode 100644
index 000000000..614133f32
--- /dev/null
+++ b/packages/cozy-scripts/scripts/check-locales.js
@@ -0,0 +1,79 @@
+const fs = require('fs')
+const { ArgumentParser } = require('argparse')
+
+const setDiff = (set1, set2) => {
+  const res = []
+  for (const v of set1) {
+    if (!set2.has(v)) {
+      res.push(v)
+    }
+  }
+  return res
+}
+
+const diff = (obj1, obj2) => {
+  const paths1 = new Set(paths(obj1))
+  const paths2 = new Set(paths(obj2))
+  const removed = Array.from(setDiff(paths1, paths2))
+  const added = Array.from(setDiff(paths2, paths1))
+  return [
+    ...added.map(x => ({ type: 'add', value: x })),
+    ...removed.map(x => ({ type: 'remove', value: x }))
+  ]
+}
+
+/** Outputs all the dotted paths of an object */
+const paths = (obj, current = '') => {
+  let res = []
+  for (let [k, v] of Object.entries(obj)) {
+    if (typeof v === 'object') {
+      for (const leaf of paths(v, current ? `${current}.${k}` : k)) {
+        res.push(`${leaf}`)
+      }
+    } else {
+      res.push(`${current}.${k}`)
+    }
+  }
+  return res
+}
+
+const main = () => {
+  const parser = new ArgumentParser({
+    description: `This scripts checks for differing keys between two locale files
+It is used to check if a given locale file (file2) is up to date
+with respect to another locale file (file1).
+Usage: check-locales.js en.json fr.json`
+  })
+  parser.addArgument('file1', {
+    nargs: '?',
+    defaultValue: 'src/locales/en.json'
+  })
+  parser.addArgument('file2', {
+    nargs: '?',
+    defaultValue: 'src/locales/fr.json'
+  })
+
+  // argv[0] will be node
+  // argv[1] will be cozy-scripts
+  // argv[2] will be check-locales
+  const args = parser.parseArgs(process.argv.slice(3))
+
+  const { file1, file2 } = args
+  const diffs = diff(
+    JSON.parse(fs.readFileSync(file1)),
+    JSON.parse(fs.readFileSync(file2))
+  )
+
+  if (diffs.length > 0) {
+    for (let d of diffs) {
+      console.log(d.type === 'add' ? '+' : '-', d.value)
+    }
+    console.warn(`Locales ${file1} and ${file2} mismatch, see diff above`)
+    process.exit(1)
+  } else {
+    console.log('Locales have the same keys, everything OK')
+    process.exit(0)
+  }
+}
+
+module.exports = main