diff --git a/server.js b/server.js
index b2eeeff70..d38c5830f 100644
--- a/server.js
+++ b/server.js
@@ -53,7 +53,7 @@ app.use(bodyParser.json())
 app.use(bodyParser.urlencoded({ extended: false }))
 // Validate some params for the API
 app.use(expressValidator({
-  customValidators: customValidators
+  customValidators: Object.assign({}, customValidators.misc, customValidators.users, customValidators.videos)
 }))
 
 // ----------- Views, routes and static files -----------
diff --git a/server/helpers/custom-validators/index.js b/server/helpers/custom-validators/index.js
new file mode 100644
index 000000000..ab3066822
--- /dev/null
+++ b/server/helpers/custom-validators/index.js
@@ -0,0 +1,15 @@
+'use strict'
+
+const miscValidators = require('./misc')
+const usersValidators = require('./users')
+const videosValidators = require('./videos')
+
+const validators = {
+  misc: miscValidators,
+  users: usersValidators,
+  videos: videosValidators
+}
+
+// ---------------------------------------------------------------------------
+
+module.exports = validators
diff --git a/server/helpers/custom-validators/misc.js b/server/helpers/custom-validators/misc.js
new file mode 100644
index 000000000..782ae3dee
--- /dev/null
+++ b/server/helpers/custom-validators/misc.js
@@ -0,0 +1,18 @@
+'use strict'
+
+const miscValidators = {
+  exists: exists,
+  isArray: isArray
+}
+
+function exists (value) {
+  return value !== undefined && value !== null
+}
+
+function isArray (value) {
+  return Array.isArray(value)
+}
+
+// ---------------------------------------------------------------------------
+
+module.exports = miscValidators
diff --git a/server/helpers/custom-validators/users.js b/server/helpers/custom-validators/users.js
new file mode 100644
index 000000000..41e00d046
--- /dev/null
+++ b/server/helpers/custom-validators/users.js
@@ -0,0 +1,18 @@
+'use strict'
+
+const validator = require('express-validator').validator
+
+const constants = require('../../initializers/constants')
+const USERS_CONSTRAINTS_FIELDS = constants.CONSTRAINTS_FIELDS.USERS
+
+const usersValidators = {
+  isUserUsernameValid: isUserUsernameValid
+}
+
+function isUserUsernameValid (value) {
+  return validator.isLength(value, USERS_CONSTRAINTS_FIELDS.USERNAME)
+}
+
+// ---------------------------------------------------------------------------
+
+module.exports = usersValidators
diff --git a/server/helpers/custom-validators.js b/server/helpers/custom-validators/videos.js
similarity index 86%
rename from server/helpers/custom-validators.js
rename to server/helpers/custom-validators/videos.js
index b666644c0..39a19cbd7 100644
--- a/server/helpers/custom-validators.js
+++ b/server/helpers/custom-validators/videos.js
@@ -2,13 +2,13 @@
 
 const validator = require('express-validator').validator
 
-const constants = require('../initializers/constants')
-const VIDEOS_CONSTRAINTS_FIELDS = constants.VIDEOS_CONSTRAINTS_FIELDS
+const constants = require('../../initializers/constants')
+const usersValidators = require('./users')
+const miscValidators = require('./misc')
+const VIDEOS_CONSTRAINTS_FIELDS = constants.CONSTRAINTS_FIELDS.VIDEOS
 
-const customValidators = {
-  exists: exists,
+const videosValidators = {
   isEachRemoteVideosValid: isEachRemoteVideosValid,
-  isArray: isArray,
   isVideoAuthorValid: isVideoAuthorValid,
   isVideoDateValid: isVideoDateValid,
   isVideoDescriptionValid: isVideoDescriptionValid,
@@ -21,10 +21,6 @@ const customValidators = {
   isVideoThumbnail64Valid: isVideoThumbnail64Valid
 }
 
-function exists (value) {
-  return value !== undefined && value !== null
-}
-
 function isEachRemoteVideosValid (requests) {
   return requests.every(function (request) {
     const video = request.data
@@ -48,20 +44,8 @@ function isEachRemoteVideosValid (requests) {
   })
 }
 
-function isArray (value) {
-  return Array.isArray(value)
-}
-
-function isRequestTypeAddValid (value) {
-  return value === 'add'
-}
-
-function isRequestTypeRemoveValid (value) {
-  return value === 'remove'
-}
-
 function isVideoAuthorValid (value) {
-  return validator.isLength(value, VIDEOS_CONSTRAINTS_FIELDS.AUTHOR)
+  return usersValidators.isUserUsernameValid(usersValidators)
 }
 
 function isVideoDateValid (value) {
@@ -90,7 +74,7 @@ function isVideoPodUrlValid (value) {
 }
 
 function isVideoTagsValid (tags) {
-  return isArray(tags) &&
+  return miscValidators.isArray(tags) &&
          validator.isInt(tags.length, VIDEOS_CONSTRAINTS_FIELDS.TAGS) &&
          tags.every(function (tag) {
            return validator.isAlphanumeric(tag) &&
@@ -109,6 +93,14 @@ function isVideoThumbnail64Valid (value) {
 
 // ---------------------------------------------------------------------------
 
-module.exports = customValidators
+module.exports = videosValidators
 
 // ---------------------------------------------------------------------------
+
+function isRequestTypeAddValid (value) {
+  return value === 'add'
+}
+
+function isRequestTypeRemoveValid (value) {
+  return value === 'remove'
+}
diff --git a/server/initializers/constants.js b/server/initializers/constants.js
index 467816f2c..5f4aeccc6 100644
--- a/server/initializers/constants.js
+++ b/server/initializers/constants.js
@@ -3,6 +3,23 @@
 // API version of our pod
 const API_VERSION = 'v1'
 
+const CONSTRAINTS_FIELDS = {
+  USERS: {
+    USERNAME: { min: 3, max: 20 }, // Length
+    PASSWORD: { min: 6, max: 255 } // Length
+  },
+  VIDEOS: {
+    NAME: { min: 3, max: 50 }, // Length
+    DESCRIPTION: { min: 3, max: 250 }, // Length
+    MAGNET_URI: { min: 10 }, // Length
+    DURATION: { min: 1, max: 7200 }, // Number
+    TAGS: { min: 1, max: 3 }, // Number of total tags
+    TAG: { min: 2, max: 10 }, // Length
+    THUMBNAIL: { min: 2, max: 30 },
+    THUMBNAIL64: { min: 0, max: 20000 } // Bytes
+  }
+}
+
 // Score a pod has when we create it as a friend
 const FRIEND_SCORE = {
   BASE: 100,
@@ -55,29 +72,18 @@ const THUMBNAILS_SIZE = '200x110'
 // Path for access to thumbnails with express router
 const THUMBNAILS_STATIC_PATH = '/static/thumbnails'
 
-const VIDEOS_CONSTRAINTS_FIELDS = {
-  NAME: { min: 3, max: 50 }, // Length
-  DESCRIPTION: { min: 3, max: 250 }, // Length
-  MAGNET_URI: { min: 10 }, // Length
-  DURATION: { min: 1, max: 7200 }, // Number
-  AUTHOR: { min: 3, max: 20 }, // Length
-  TAGS: { min: 1, max: 3 }, // Number of total tags
-  TAG: { min: 2, max: 10 }, // Length
-  THUMBNAIL: { min: 2, max: 30 },
-  THUMBNAIL64: { min: 0, max: 20000 } // Bytes
-}
-
 // Special constants for a test instance
 if (isTestInstance() === true) {
   FRIEND_SCORE.BASE = 20
   INTERVAL = 10000
-  VIDEOS_CONSTRAINTS_FIELDS.DURATION.max = 14
+  CONSTRAINTS_FIELDS.VIDEOS.DURATION.max = 14
 }
 
 // ---------------------------------------------------------------------------
 
 module.exports = {
   API_VERSION: API_VERSION,
+  CONSTRAINTS_FIELDS: CONSTRAINTS_FIELDS,
   FRIEND_SCORE: FRIEND_SCORE,
   INTERVAL: INTERVAL,
   OAUTH_LIFETIME: OAUTH_LIFETIME,
@@ -90,8 +96,7 @@ module.exports = {
   SEEDS_IN_PARALLEL: SEEDS_IN_PARALLEL,
   SORTABLE_COLUMNS: SORTABLE_COLUMNS,
   THUMBNAILS_SIZE: THUMBNAILS_SIZE,
-  THUMBNAILS_STATIC_PATH: THUMBNAILS_STATIC_PATH,
-  VIDEOS_CONSTRAINTS_FIELDS: VIDEOS_CONSTRAINTS_FIELDS
+  THUMBNAILS_STATIC_PATH: THUMBNAILS_STATIC_PATH
 }
 
 // ---------------------------------------------------------------------------
diff --git a/server/middlewares/validators/videos.js b/server/middlewares/validators/videos.js
index 3e2af06fb..422f3642f 100644
--- a/server/middlewares/validators/videos.js
+++ b/server/middlewares/validators/videos.js
@@ -4,7 +4,7 @@ const mongoose = require('mongoose')
 
 const checkErrors = require('./utils').checkErrors
 const constants = require('../../initializers/constants')
-const customValidators = require('../../helpers/custom-validators')
+const customVideosValidators = require('../../helpers/custom-validators').videos
 const logger = require('../../helpers/logger')
 
 const Video = mongoose.model('Video')
@@ -33,8 +33,8 @@ function videosAdd (req, res, next) {
         return res.status(400).send('Cannot retrieve metadata of the file.')
       }
 
-      if (!customValidators.isVideoDurationValid(duration)) {
-        return res.status(400).send('Duration of the video file is too big (max: ' + constants.VIDEOS_CONSTRAINTS_FIELDS.DURATION.max + 's).')
+      if (!customVideosValidators.isVideoDurationValid(duration)) {
+        return res.status(400).send('Duration of the video file is too big (max: ' + constants.CONSTRAINTS_FIELDS.VIDEOS.DURATION.max + 's).')
       }
 
       videoFile.duration = duration
diff --git a/server/models/video.js b/server/models/video.js
index 396aa505d..acb8353c2 100644
--- a/server/models/video.js
+++ b/server/models/video.js
@@ -9,7 +9,7 @@ const pathUtils = require('path')
 const mongoose = require('mongoose')
 
 const constants = require('../initializers/constants')
-const customValidators = require('../helpers/custom-validators')
+const customVideosValidators = require('../helpers/custom-validators').videos
 const logger = require('../helpers/logger')
 const utils = require('../helpers/utils')
 const webtorrent = require('../lib/webtorrent')
@@ -39,18 +39,18 @@ const VideoSchema = mongoose.Schema({
   }
 })
 
-VideoSchema.path('name').validate(customValidators.isVideoNameValid)
-VideoSchema.path('description').validate(customValidators.isVideoDescriptionValid)
-VideoSchema.path('magnetUri').validate(customValidators.isVideoMagnetUriValid)
-VideoSchema.path('podUrl').validate(customValidators.isVideoPodUrlValid)
-VideoSchema.path('author').validate(customValidators.isVideoAuthorValid)
-VideoSchema.path('duration').validate(customValidators.isVideoDurationValid)
+VideoSchema.path('name').validate(customVideosValidators.isVideoNameValid)
+VideoSchema.path('description').validate(customVideosValidators.isVideoDescriptionValid)
+VideoSchema.path('magnetUri').validate(customVideosValidators.isVideoMagnetUriValid)
+VideoSchema.path('podUrl').validate(customVideosValidators.isVideoPodUrlValid)
+VideoSchema.path('author').validate(customVideosValidators.isVideoAuthorValid)
+VideoSchema.path('duration').validate(customVideosValidators.isVideoDurationValid)
 // The tumbnail can be the path or the data in base 64
 // The pre save hook will convert the base 64 data in a file on disk and replace the thumbnail key by the filename
 VideoSchema.path('thumbnail').validate(function (value) {
-  return customValidators.isVideoThumbnailValid(value) || customValidators.isVideoThumbnail64Valid(value)
+  return customVideosValidators.isVideoThumbnailValid(value) || customVideosValidators.isVideoThumbnail64Valid(value)
 })
-VideoSchema.path('tags').validate(customValidators.isVideoTagsValid)
+VideoSchema.path('tags').validate(customVideosValidators.isVideoTagsValid)
 
 VideoSchema.methods = {
   isOwned: isOwned,