diff --git a/.gitignore b/.gitignore
index af45a45..fe3192f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,4 +33,3 @@ npm-debug.log*
 
 # misc
 .DS_Store
-uploads
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index e9408b7..203308a 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -9,12 +9,12 @@ generator client {
 
 model User {
   id                       Int            @id @default(autoincrement())
-  name                     String         @unique @db.VarChar(255)
-  email                    String?        @unique @db.VarChar(255)
+  name                     String         @unique @db.VarChar(30)
+  email                    String?        @unique @db.VarChar(254)
   password                 String?        @db.Text
   logo                     String?        @db.Text
-  status                   String?        @db.VarChar(255)
-  biography                String?        @db.Text
+  status                   String?        @db.VarChar(50)
+  biography                String?        @db.VarChar(160)
   website                  String?        @db.VarChar(255)
   isConfirmed              Boolean        @default(false)
   temporaryToken           String?
@@ -29,8 +29,8 @@ model User {
 
 model UserSetting {
   id             Int      @id @default(autoincrement())
-  language       String   @default("en") @db.VarChar(255)
-  theme          String   @default("dark") @db.VarChar(255)
+  language       String   @default("en") @db.VarChar(10)
+  theme          String   @default("dark") @db.VarChar(10)
   isPublicEmail  Boolean  @default(false)
   isPublicGuilds Boolean  @default(false)
   createdAt      DateTime @default(now())
@@ -51,7 +51,7 @@ model RefreshToken {
 model OAuth {
   id         Int      @id @default(autoincrement())
   providerId String   @db.Text
-  provider   String   @db.VarChar(255)
+  provider   String   @db.VarChar(20)
   createdAt  DateTime @default(now())
   updatedAt  DateTime @default(now()) @updatedAt
   userId     Int      @unique
@@ -72,7 +72,7 @@ model Member {
 
 model Guild {
   id          Int       @id @default(autoincrement())
-  name        String    @db.VarChar(255)
+  name        String    @db.VarChar(30)
   icon        String?   @db.Text
   description String?   @db.Text
   createdAt   DateTime  @default(now())
@@ -83,7 +83,7 @@ model Guild {
 
 model Channel {
   id        Int       @id @default(autoincrement())
-  name      String    @db.VarChar(255)
+  name      String    @db.VarChar(20)
   createdAt DateTime  @default(now())
   updatedAt DateTime  @default(now()) @updatedAt
   guildId   Int       @unique
@@ -94,8 +94,8 @@ model Channel {
 model Message {
   id        Int      @id @default(autoincrement())
   value     String   @db.Text
-  type      String   @default("text") @db.VarChar(255)
-  mimetype  String   @default("text/plain") @db.VarChar(255)
+  type      String   @default("text") @db.VarChar(10)
+  mimetype  String   @default("text/plain") @db.VarChar(127)
   createdAt DateTime @default(now())
   updatedAt DateTime @default(now()) @updatedAt
   memberId  Int      @unique
diff --git a/src/models/Channel.ts b/src/models/Channel.ts
index ae00345..385e283 100644
--- a/src/models/Channel.ts
+++ b/src/models/Channel.ts
@@ -8,7 +8,7 @@ export const types = [Type.Literal('text')]
 
 export const channelSchema = {
   id,
-  name: Type.String({ maxLength: 255 }),
+  name: Type.String({ minLength: 1, maxLength: 20 }),
   createdAt: date.createdAt,
   updatedAt: date.updatedAt,
   guildId: id
diff --git a/src/models/Guild.ts b/src/models/Guild.ts
index 362863a..1f6caac 100644
--- a/src/models/Guild.ts
+++ b/src/models/Guild.ts
@@ -5,9 +5,9 @@ import { date, id } from './utils.js'
 
 export const guildSchema = {
   id,
-  name: Type.String({ minLength: 3, maxLength: 30 }),
-  icon: Type.String({ format: 'uri-reference' }),
-  description: Type.String({ maxLength: 160 }),
+  name: Type.String({ minLength: 1, maxLength: 30 }),
+  icon: Type.Union([Type.String({ format: 'uri-reference' }), Type.Null()]),
+  description: Type.Union([Type.String({ maxLength: 160 }), Type.Null()]),
   createdAt: date.createdAt,
   updatedAt: date.updatedAt
 }
diff --git a/src/models/Message.ts b/src/models/Message.ts
index 9197a52..fbe6d59 100644
--- a/src/models/Message.ts
+++ b/src/models/Message.ts
@@ -6,10 +6,13 @@ export const types = [Type.Literal('text'), Type.Literal('file')]
 
 export const messageSchema = {
   id,
-  value: Type.String(),
+  value: Type.String({
+    minLength: 1,
+    maxLength: 20_000
+  }),
   type: Type.Union(types, { default: 'text' }),
   mimetype: Type.String({
-    maxLength: 255,
+    maxLength: 127,
     default: 'text/plain',
     format: 'mimetype'
   }),
diff --git a/src/models/User.ts b/src/models/User.ts
index 91effd8..05b322d 100644
--- a/src/models/User.ts
+++ b/src/models/User.ts
@@ -19,11 +19,11 @@ export interface UserRequest {
 export const userSchema = {
   id,
   name: Type.String({ minLength: 1, maxLength: 30 }),
-  email: Type.String({ minLength: 1, maxLength: 255, format: 'email' }),
+  email: Type.String({ minLength: 1, maxLength: 254, format: 'email' }),
   password: Type.String(),
   logo: Type.String({ format: 'uri-reference' }),
-  status: Type.String({ maxLength: 255 }),
-  biography: Type.String(),
+  status: Type.String({ maxLength: 50 }),
+  biography: Type.String({ maxLength: 160 }),
   website: Type.String({ maxLength: 255, format: 'uri-reference' }),
   isConfirmed: Type.Boolean({ default: false }),
   temporaryToken: Type.String(),
@@ -32,18 +32,22 @@ export const userSchema = {
   updatedAt: date.updatedAt
 }
 
-export const userPublicSchema = {
+export const userPublicWithoutSettingsSchema = {
   id,
   name: userSchema.name,
-  email: Type.Optional(userSchema.email),
-  logo: Type.Optional(userSchema.logo),
-  status: Type.Optional(userSchema.status),
-  biography: Type.Optional(userSchema.biography),
-  website: Type.Optional(userSchema.website),
+  email: Type.Union([userSchema.email, Type.Null()]),
+  logo: Type.Union([userSchema.logo, Type.Null()]),
+  status: Type.Union([userSchema.status, Type.Null()]),
+  biography: Type.Union([userSchema.biography, Type.Null()]),
+  website: Type.Union([userSchema.website, Type.Null()]),
   isConfirmed: userSchema.isConfirmed,
   createdAt: date.createdAt,
-  updatedAt: date.updatedAt,
-  settings: Type.Optional(Type.Object(userSettingsSchema))
+  updatedAt: date.updatedAt
+}
+
+export const userPublicSchema = {
+  ...userPublicWithoutSettingsSchema,
+  settings: Type.Object(userSettingsSchema)
 }
 
 export const userCurrentSchema = Type.Object({
diff --git a/src/services/guilds/[guildId]/icon/put.ts b/src/services/guilds/[guildId]/icon/put.ts
new file mode 100644
index 0000000..480214a
--- /dev/null
+++ b/src/services/guilds/[guildId]/icon/put.ts
@@ -0,0 +1,80 @@
+import { Static, Type } from '@sinclair/typebox'
+import { FastifyPluginAsync, FastifySchema } from 'fastify'
+
+import authenticateUser from '../../../../tools/plugins/authenticateUser.js'
+import { fastifyErrors } from '../../../../models/utils.js'
+import fastifyMultipart from 'fastify-multipart'
+import prisma from '../../../../tools/database/prisma.js'
+import { uploadImage } from '../../../../tools/utils/uploadImage.js'
+import { guildSchema } from '../../../../models/Guild.js'
+
+const parametersSchema = Type.Object({
+  guildId: guildSchema.id
+})
+
+type Parameters = Static<typeof parametersSchema>
+
+const putServiceSchema: FastifySchema = {
+  description: 'Edit the icon of the guild with its id',
+  tags: ['guilds'] as string[],
+  consumes: ['multipart/form-data'] as string[],
+  produces: ['application/json'] as string[],
+  security: [
+    {
+      bearerAuth: []
+    }
+  ] as Array<{ [key: string]: [] }>,
+  params: parametersSchema,
+  response: {
+    200: Type.Object({
+      guild: Type.Object({
+        icon: Type.String()
+      })
+    }),
+    400: fastifyErrors[400],
+    401: fastifyErrors[401],
+    403: fastifyErrors[403],
+    404: fastifyErrors[404],
+    431: fastifyErrors[431],
+    500: fastifyErrors[500]
+  }
+} as const
+
+export const putGuildIconById: FastifyPluginAsync = async (fastify) => {
+  await fastify.register(authenticateUser)
+
+  await fastify.register(fastifyMultipart)
+
+  fastify.route<{
+    Params: Parameters
+  }>({
+    method: 'PUT',
+    url: '/guilds/:guildId/icon',
+    schema: putServiceSchema,
+    handler: async (request, reply) => {
+      if (request.user == null) {
+        throw fastify.httpErrors.forbidden()
+      }
+      const { guildId } = request.params
+      const guild = await prisma.guild.findUnique({ where: { id: guildId } })
+      if (guild == null) {
+        throw fastify.httpErrors.notFound()
+      }
+      const icon = await uploadImage({
+        fastify,
+        request,
+        folderInUploadsFolder: 'guilds'
+      })
+      await prisma.guild.update({
+        where: { id: guildId },
+        data: { icon }
+      })
+      reply.statusCode = 200
+      return {
+        guild: {
+          icon
+        }
+      }
+    }
+  })
+}
diff --git a/src/services/guilds/index.ts b/src/services/guilds/index.ts
index 034d5e1..5fff260 100644
--- a/src/services/guilds/index.ts
+++ b/src/services/guilds/index.ts
@@ -1,7 +1,9 @@
 import { FastifyPluginAsync } from 'fastify'
 
 import { postGuilds } from './post.js'
+import { putGuildIconById } from './[guildId]/icon/put.js'
 
 export const guildsService: FastifyPluginAsync = async (fastify) => {
   await fastify.register(postGuilds)
+  await fastify.register(putGuildIconById)
 }
diff --git a/src/services/guilds/post.ts b/src/services/guilds/post.ts
index ef7a6fc..a3804ec 100644
--- a/src/services/guilds/post.ts
+++ b/src/services/guilds/post.ts
@@ -7,7 +7,8 @@ import authenticateUser from '../../tools/plugins/authenticateUser.js'
 import { guildSchema } from '../../models/Guild.js'
 import { channelSchema } from '../../models/Channel.js'
 import { memberSchema } from '../../models/Member.js'
-import { userPublicSchema } from '../../models/User.js'
+import { userPublicWithoutSettingsSchema } from '../../models/User.js'
+import { parseStringNullish } from '../../tools/utils/parseStringNullish.js'
 
 const bodyPostServiceSchema = Type.Object({
   name: guildSchema.name,
@@ -33,7 +34,7 @@ const postServiceSchema: FastifySchema = {
         members: Type.Array(
           Type.Object({
             ...memberSchema,
-            user: Type.Object(userPublicSchema)
+            user: Type.Object(userPublicWithoutSettingsSchema)
           })
         )
       })
@@ -59,7 +60,9 @@ export const postGuilds: FastifyPluginAsync = async (fastify) => {
         throw fastify.httpErrors.forbidden()
       }
       const { name, description } = request.body
-      const guild = await prisma.guild.create({ data: { name, description } })
+      const guild = await prisma.guild.create({
+        data: { name, description: parseStringNullish(description) }
+      })
       const channel = await prisma.channel.create({
         data: { name: 'general', guildId: guild.id }
       })
diff --git a/src/services/users/[userId]/get.ts b/src/services/users/[userId]/get.ts
index 18c3f05..0e6acb1 100644
--- a/src/services/users/[userId]/get.ts
+++ b/src/services/users/[userId]/get.ts
@@ -10,7 +10,7 @@ const parametersGetUserSchema = Type.Object({
   userId: userPublicSchema.id
 })
 
-export type ParametersGetUser = Static<typeof parametersGetUserSchema>
+type ParametersGetUser = Static<typeof parametersGetUserSchema>
 
 const getServiceSchema: FastifySchema = {
   description: 'GET the public user informations with its id',
diff --git a/src/services/users/current/logo/put.ts b/src/services/users/current/logo/put.ts
index 63a951e..f0369e5 100644
--- a/src/services/users/current/logo/put.ts
+++ b/src/services/users/current/logo/put.ts
@@ -1,19 +1,11 @@
-import fs from 'node:fs'
-import { URL } from 'node:url'
-import { randomUUID } from 'node:crypto'
-
 import { Type } from '@sinclair/typebox'
 import { FastifyPluginAsync, FastifySchema } from 'fastify'
 
 import authenticateUser from '../../../../tools/plugins/authenticateUser.js'
 import { fastifyErrors } from '../../../../models/utils.js'
-import fastifyMultipart, { Multipart } from 'fastify-multipart'
-import {
-  maximumImageSize,
-  supportedImageMimetype,
-  ROOT_URL
-} from '../../../../tools/configurations'
+import fastifyMultipart from 'fastify-multipart'
 import prisma from '../../../../tools/database/prisma.js'
+import { uploadImage } from '../../../../tools/utils/uploadImage.js'
 
 const putServiceSchema: FastifySchema = {
   description: 'Edit the current connected user logo',
@@ -52,36 +44,11 @@ export const putCurrentUserLogo: FastifyPluginAsync = async (fastify) => {
       if (request.user == null) {
         throw fastify.httpErrors.forbidden()
       }
-      let files: Multipart[] = []
-      try {
-        files = await request.saveRequestFiles({
-          limits: {
-            files: 1,
-            fileSize: maximumImageSize * 1024 * 1024
-          }
-        })
-      } catch (error) {
-        throw fastify.httpErrors.requestHeaderFieldsTooLarge(
-          `body.logo should be less than ${maximumImageSize}mb.`
-        )
-      }
-      if (files.length !== 1) {
-        throw fastify.httpErrors.badRequest('You must upload at most one file.')
-      }
-      const image = files[0]
-      if (!supportedImageMimetype.includes(image.mimetype)) {
-        throw fastify.httpErrors.badRequest(
-          `The file must have a valid type (${supportedImageMimetype.join(
-            ', '
-          )}).`
-        )
-      }
-      const splitedMimetype = image.mimetype.split('/')
-      const imageExtension = splitedMimetype[1]
-      const logoPath = `uploads/users/${randomUUID()}.${imageExtension}`
-      const logoURL = new URL(logoPath, ROOT_URL)
-      const logo = `/${logoPath}`
-      await fs.promises.copyFile(image.filepath, logoURL)
+      const logo = await uploadImage({
+        fastify,
+        request,
+        folderInUploadsFolder: 'users'
+      })
       await prisma.user.update({
         where: { id: request.user.current.id },
         data: { logo }
diff --git a/src/services/users/current/put.ts b/src/services/users/current/put.ts
index 68d375c..af915d0 100644
--- a/src/services/users/current/put.ts
+++ b/src/services/users/current/put.ts
@@ -10,6 +10,7 @@ import { userCurrentSchema, userSchema } from '../../../models/User.js'
 import { sendEmail } from '../../../tools/email/sendEmail.js'
 import { HOST, PORT } from '../../../tools/configurations/index.js'
 import { Language, Theme } from '../../../models/UserSettings.js'
+import { parseStringNullish } from '../../../tools/utils/parseStringNullish.js'
 
 const bodyPutServiceSchema = Type.Object({
   name: Type.Optional(userSchema.name),
@@ -117,9 +118,12 @@ export const putCurrentUser: FastifyPluginAsync = async (fastify) => {
         where: { id: request.user.current.id },
         data: {
           name: name ?? request.user.current.name,
-          status: status ?? request.user.current.status,
-          biography: biography ?? request.user.current.biography,
-          website: website ?? request.user.current.website
+          status: parseStringNullish(request.user.current.status, status),
+          biography: parseStringNullish(
+            request.user.current.biography,
+            biography
+          ),
+          website: parseStringNullish(request.user.current.website, website)
         }
       })
       reply.statusCode = 200
diff --git a/src/tools/utils/__test__/OAuthStrategy.test.ts b/src/tools/utils/__test__/OAuthStrategy.test.ts
index 1b63df4..d2e8a60 100644
--- a/src/tools/utils/__test__/OAuthStrategy.test.ts
+++ b/src/tools/utils/__test__/OAuthStrategy.test.ts
@@ -5,7 +5,7 @@ import { OAuthStrategy } from '../OAuthStrategy.js'
 
 const oauthStrategy = new OAuthStrategy('discord')
 
-describe('/utils/OAuthStrategy - callbackSignin', () => {
+describe('/tools/utils/OAuthStrategy - callbackSignin', () => {
   it('should signup the user', async () => {
     const name = 'Martin'
     const id = '12345'
@@ -52,7 +52,7 @@ describe('/utils/OAuthStrategy - callbackSignin', () => {
   })
 })
 
-describe('/utils/OAuthStrategy - callbackAddStrategy', () => {
+describe('/tools/utils/OAuthStrategy - callbackAddStrategy', () => {
   it('should add the strategy to the user', async () => {
     const name = userExample.name
     const id = '12345'
diff --git a/src/tools/utils/__test__/buildQueryURL.test.ts b/src/tools/utils/__test__/buildQueryURL.test.ts
index 79611e2..9f554b9 100644
--- a/src/tools/utils/__test__/buildQueryURL.test.ts
+++ b/src/tools/utils/__test__/buildQueryURL.test.ts
@@ -1,6 +1,6 @@
 import { buildQueryURL } from '../buildQueryURL.js'
 
-test('controllers/users/utils/buildQueryUrl', () => {
+test('/tools/utils/buildQueryUrl', () => {
   expect(
     buildQueryURL('http://localhost:8080', {
       test: 'query'
diff --git a/src/tools/utils/__test__/parseStringNullish.test.ts b/src/tools/utils/__test__/parseStringNullish.test.ts
new file mode 100644
index 0000000..65801d4
--- /dev/null
+++ b/src/tools/utils/__test__/parseStringNullish.test.ts
@@ -0,0 +1,17 @@
+import { parseStringNullish } from '../parseStringNullish'
+
+const defaultString = 'defaultString'
+
+describe('/tools/utils/parseStringNullish', () => {
+  it('returns `null` if `string.length === 0`', () => {
+    expect(parseStringNullish(defaultString, '')).toEqual(null)
+  })
+
+  it('returns `defaultString` if `string == null`', () => {
+    expect(parseStringNullish(defaultString)).toEqual(defaultString)
+  })
+
+  it('returns `string` if `string.length > 0`', () => {
+    expect(parseStringNullish(defaultString, 'string')).toEqual('string')
+  })
+})
diff --git a/src/tools/utils/parseStringNullish.ts b/src/tools/utils/parseStringNullish.ts
new file mode 100644
index 0000000..b49e895
--- /dev/null
+++ b/src/tools/utils/parseStringNullish.ts
@@ -0,0 +1,21 @@
+/**
+ * Parse a nullish string:
+ *  - if `string.length === 0`, it returns `null`
+ *  - if `string == null`, it returns `defaultString`
+ *  - if `string.length > 0`, it returns `string`
+ * @param defaultString
+ * @param string
+ * @returns
+ */
+export const parseStringNullish = (
+  defaultString: string | null,
+  string?: string
+): string | null => {
+  if (string != null) {
+    if (string.length > 0) {
+      return string
+    }
+    return null
+  }
+  return defaultString
+}
diff --git a/src/tools/utils/uploadImage.ts b/src/tools/utils/uploadImage.ts
new file mode 100644
index 0000000..91a4cc0
--- /dev/null
+++ b/src/tools/utils/uploadImage.ts
@@ -0,0 +1,54 @@
+import fs from 'node:fs'
+import { URL } from 'node:url'
+import { randomUUID } from 'node:crypto'
+
+import { FastifyInstance, FastifyRequest } from 'fastify'
+
+import { Multipart } from 'fastify-multipart'
+
+import {
+  maximumImageSize,
+  supportedImageMimetype,
+  ROOT_URL
+} from '../configurations'
+
+export interface UploadImageOptions {
+  folderInUploadsFolder: 'guilds' | 'messages' | 'users'
+  request: FastifyRequest
+  fastify: FastifyInstance
+}
+
+export const uploadImage = async (
+  options: UploadImageOptions
+): Promise<string> => {
+  const { fastify, request, folderInUploadsFolder } = options
+  let files: Multipart[] = []
+  try {
+    files = await request.saveRequestFiles({
+      limits: {
+        files: 1,
+        fileSize: maximumImageSize * 1024 * 1024
+      }
+    })
+  } catch (error) {
+    throw fastify.httpErrors.requestHeaderFieldsTooLarge(
+      `Image should be less than ${maximumImageSize}mb.`
+    )
+  }
+  if (files.length !== 1) {
+    throw fastify.httpErrors.badRequest('You must upload at most one file.')
+  }
+  const image = files[0]
+  if (!supportedImageMimetype.includes(image.mimetype)) {
+    throw fastify.httpErrors.badRequest(
+      `The file must have a valid type (${supportedImageMimetype.join(', ')}).`
+    )
+  }
+  const splitedMimetype = image.mimetype.split('/')
+  const imageExtension = splitedMimetype[1]
+  const imagePath = `uploads/${folderInUploadsFolder}/${randomUUID()}.${imageExtension}`
+  const imageURL = new URL(imagePath, ROOT_URL)
+  const imagePathToStoreInDatabase = `/${imagePath}`
+  await fs.promises.copyFile(image.filepath, imageURL)
+  return imagePathToStoreInDatabase
+}
diff --git a/uploads/guilds/.gitkeep b/uploads/guilds/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/uploads/guilds/default.png b/uploads/guilds/default.png
deleted file mode 100644
index 826659b..0000000
Binary files a/uploads/guilds/default.png and /dev/null differ
diff --git a/uploads/users/.gitkeep b/uploads/users/.gitkeep
new file mode 100644
index 0000000..e69de29
diff --git a/uploads/users/default.png b/uploads/users/default.png
deleted file mode 100644
index d3d6fbe..0000000
Binary files a/uploads/users/default.png and /dev/null differ