diff --git a/app/src/main/graphql/org/ddnss/sfs/schema.graphqls b/app/src/main/graphql/org/ddnss/sfs/schema.graphqls
new file mode 100644
index 0000000..0e45734
--- /dev/null
+++ b/app/src/main/graphql/org/ddnss/sfs/schema.graphqls
@@ -0,0 +1,166 @@
+type Message {
+  id: ID!
+
+  timestamp: String!
+
+  sender: ID!
+
+  msgType: MsgType!
+
+  content: String
+
+  hideFor: [ID!]
+
+  seenBy: [ID!]!
+}
+
+type ExternalServersPreferences {
+  privacyPreferences: PrivacyPreferences!
+
+  externalServers: RestrictionPolicy!
+
+  externalServersLimit: [Url!]!
+}
+
+type Mutation {
+  newUser(newUser: NewUser!): ID!
+
+  newChat(user: ID!, passwordHash: String!, with: ID!): ID!
+
+  newGroupChat(user: ID!, passwordHash: String!, title: String!, description: String, with: [ID!]!): ID!
+
+  sendMessage(user: ID!, passwordHash: String!, chat: ID!, msg: MessageInput!): ID!
+}
+
+enum RestrictionPolicy {
+  EVERYONE
+
+  EXCLUDING
+
+  INCLUDING
+
+  NONE
+}
+
+type NotificationPreferences {
+  lockDetails: Boolean!
+
+  doNotDisturb: Boolean!
+}
+
+"""
+DateTime
+"""
+scalar DateTimeUtc
+
+"""
+Url
+"""
+scalar Url
+
+type Query {
+  getUserID(username: String!): ID!
+
+  isUsernameUsed(username: String!): Boolean!
+
+  users: [User!]!
+
+  userPreferences(id: ID!, passwordHash: String!): UserPreferences!
+
+  chats(user: ID!, passwordHash: String!): [Chat!]!
+
+  groupChats(user: ID!, passwordHash: String!): [GroupChat!]!
+
+  getMessages(user: ID!, passwordHash: String!, chat: ID!, lastMsg: ID, limit: Int): [Message!]!
+}
+
+type SecurityPreferences {
+  accountTokens: [ID!]!
+
+  passwordHash: String!
+}
+
+type PrivacyPreferences {
+  discovery: RestrictionPolicy!
+
+  discoveryUserLimit: [String!]!
+
+  discoveryServerLimit: [Url!]!
+
+  lastSeen: RestrictionPolicy!
+
+  lastSeenUserLimit: [String!]!
+
+  lastSeenServerLimit: [Url!]!
+
+  lastSeenCourse: Boolean!
+
+  info: RestrictionPolicy!
+
+  infoUserLimit: [String!]!
+
+  infoServerLimit: [Url!]!
+}
+
+type UserPreferences {
+  privacyPreferences: PrivacyPreferences!
+
+  notificationPreferences: NotificationPreferences!
+
+  securityPreferences: SecurityPreferences!
+
+  externalServersPreferences: ExternalServersPreferences!
+}
+
+input NewUser {
+  userName: String!
+
+  displayName: String
+
+  passwordHash: String!
+}
+
+input MessageInput {
+  msgType: MsgType!
+
+  content: String
+}
+
+type User {
+  id: ID!
+
+  userName: String!
+
+  displayName: String
+
+  activated: Boolean!
+
+  created: DateTimeUtc!
+
+  lastOnline: DateTimeUtc
+}
+
+enum MsgType {
+  TEXT
+}
+
+type Chat {
+  id: ID!
+
+  users: [ID!]!
+}
+
+type GroupChat {
+  id: ID!
+
+  title: String!
+
+  description: String
+
+  users: [ID!]!
+}
+
+schema {
+  query: Query
+  mutation: Mutation
+}