Todo App Backend Template
Schema, API & AI Agent

Key Takeaways

Overview

A Todo app is one of the most common starting points for learning backend development. Under the hood it needs user registration, task CRUD, ownership-based access control, and optionally real-time sync.

The schema below defines two classes — _User (built-in) and Todo — connected by a Pointer. With the Back4app SDK for your chosen technology, you can interact with this backend — querying, creating, updating, and deleting objects — without writing a custom API layer.

Why Build Your Todo Backend with Back4app?

Back4app gives you a ready backend with SDKs for every major platform so you can build your Todo app without writing REST glue or managing auth yourself.

• •SDKs for every stack Flutter, React, Android, iOS, Vue, Angular, .NET — or use REST / GraphQL from any language.
• •Auth & ACLs out of the box user sign-up, login, session tokens, and row-level access control with no custom middleware.
• •Real-time & offline Live Queries over WebSockets for instant UI updates; supported SDKs offer local datastore pinning for offline-first apps.
• •Flexible schema add fields from the dashboard or API at any time — no migrations, no downtime.

Same schema and APIs for every stack — switch clients later without changing the backend.

Core Benefits

A production-ready Todo backend so you can ship faster and focus on your app.

Technical Stack

Everything powering this Todo app template at a glance.

ER Diagram

Entity-Relationship diagram for the Todo app data model.

erDiagram
    _User {
        String objectId PK
        String username
        String email
        String password
        Date createdAt
        Date updatedAt
    }

    Todo {
        String objectId PK
        String title
        Boolean done
        Date dueDate
        Number priority
        Pointer owner FK
        Date createdAt
        Date updatedAt
    }

    _User ||--o{ Todo : "owns"

Integration Flow

Auth-to-CRUD sequence: how your app talks to Back4app — login, then query and create todos.

sequenceDiagram
  participant User
  participant App as Your App
  participant Back4app as Back4app Cloud

  User->>App: Login
  App->>Back4app: POST /login (username, password)
  Back4app-->>App: Session token
  App-->>User: Logged in

  User->>App: Load todos
  App->>Back4app: GET /classes/Todo
  Back4app-->>App: List of Todo objects
  App-->>User: Show list

  User->>App: Create todo
  App->>Back4app: POST /classes/Todo
  Back4app-->>App: Todo (objectId)
  App-->>User: Updated list

Data Dictionary

Complete field reference for every class in the schema.

Security & Permissions

How ownership, ACLs, and class-level permissions protect data in this schema.

Schema (JSON)

Raw JSON schema definition — copy and use in your Back4app app or import via the API.

{
  "classes": [
    {
      "className": "Todo",
      "fields": {
        "objectId": {
          "type": "String",
          "required": false
        },
        "title": {
          "type": "String",
          "required": true
        },
        "done": {
          "type": "Boolean",
          "required": false,
          "defaultValue": false
        },
        "dueDate": {
          "type": "Date",
          "required": false
        },
        "priority": {
          "type": "Number",
          "required": false,
          "defaultValue": 3
        },
        "owner": {
          "type": "Pointer",
          "targetClass": "_User",
          "required": false
        },
        "createdAt": {
          "type": "Date",
          "required": false
        },
        "updatedAt": {
          "type": "Date",
          "required": false
        }
      }
    },
    {
      "className": "_User",
      "fields": {
        "objectId": {
          "type": "String",
          "required": false
        },
        "username": {
          "type": "String",
          "required": true
        },
        "email": {
          "type": "String",
          "required": true
        },
        "password": {
          "type": "String",
          "required": true
        },
        "createdAt": {
          "type": "Date",
          "required": false
        },
        "updatedAt": {
          "type": "Date",
          "required": false
        }
      }
    }
  ]
}

API Playground

Try the REST and GraphQL endpoints for the Todo schema. Responses from the example data above — no Back4app account needed.

Uses the same Todo schema as this template.

What You Get with Every Technology

No matter which technology you pick, every guide and deployment shares this backend.

Frequently Asked Questions

Common questions about the Todo app backend template.