diff --git a/src/permissions/permissions.module.ts b/src/permissions/permissions.module.ts
index 9d0d334e2..16e4e0db8 100644
--- a/src/permissions/permissions.module.ts
+++ b/src/permissions/permissions.module.ts
@@ -9,11 +9,10 @@ import { TypeOrmModule } from '@nestjs/typeorm';
 import { LoggerModule } from '../logger/logger.module';
 import { NoteGroupPermission } from './note-group-permission.entity';
 import { NoteUserPermission } from './note-user-permission.entity';
+import { PermissionsService } from './permissions.service';
 
 @Module({
-  imports: [
-    TypeOrmModule.forFeature([NoteUserPermission, NoteGroupPermission]),
-    LoggerModule,
-  ],
+  exports: [PermissionsService],
+  providers: [PermissionsService],
 })
 export class PermissionsModule {}
diff --git a/src/permissions/permissions.service.ts b/src/permissions/permissions.service.ts
new file mode 100644
index 000000000..8c5edf585
--- /dev/null
+++ b/src/permissions/permissions.service.ts
@@ -0,0 +1,100 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Injectable } from '@nestjs/common';
+import { User } from '../users/user.entity';
+import { Note } from '../notes/note.entity';
+import { ConsoleLoggerService } from '../logger/console-logger.service';
+
+@Injectable()
+export class PermissionsService {
+  constructor(private readonly logger: ConsoleLoggerService) {}
+  mayRead(user: User, note: Note): boolean {
+    if (this.isOwner(user, note)) return true;
+
+    if (this.hasPermissionUser(user, note, false)) return true;
+
+    if (this.hasPermissionGroup(user, note, false)) return true;
+
+    return false;
+  }
+
+  mayWrite(user: User, note: Note): boolean {
+    if (this.isOwner(user, note)) return true;
+
+    if (this.hasPermissionUser(user, note, true)) return true;
+
+    if (this.hasPermissionGroup(user, note, true)) return true;
+
+    return false;
+  }
+  mayCreate(user: User): boolean {
+    if (user) {
+      // TODO: (config.guestPermission == "create")
+      return true;
+    }
+    return false;
+  }
+  isOwner(user: User, note: Note): boolean {
+    if (!user) return false;
+    return note.owner.id === user.id;
+  }
+
+  private hasPermissionUser(
+    user: User,
+    note: Note,
+    wantEdit: boolean,
+  ): boolean {
+    if (!user) {
+      return false;
+    }
+    for (const userPermission of note.userPermissions) {
+      if (
+        userPermission.user.id === user.id &&
+        (userPermission.canEdit || !wantEdit)
+      ) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  private hasPermissionGroup(
+    user: User,
+    note: Note,
+    wantEdit: boolean,
+  ): boolean {
+    // TODO: Get real config value
+    const guestsAllowed = false; // (config.guestPermission == "write" || config.guestPermission == "read" && !wantEdit)
+    for (const groupPermission of note.groupPermissions) {
+      if (groupPermission.canEdit || !wantEdit) {
+        // Handle special groups
+        if (groupPermission.group.special) {
+          if (groupPermission.group.name == 'loggedIn') {
+            // TODO: Name of group for logged in users
+            return true;
+          }
+          if (
+            groupPermission.group.name == 'everybody' &&
+            (groupPermission.canEdit || !wantEdit) &&
+            guestsAllowed
+          ) {
+            // TODO: Name of group in which everybody even guests can edit
+            return true;
+          }
+        } else {
+          // Handle normal groups
+          if (user) {
+            for (const member of groupPermission.group.members) {
+              if (member.id === user.id) return true;
+            }
+          }
+        }
+      }
+    }
+    return false;
+  }
+}