Backend

Databases, APIs, Cloud Code, and the managed Parse platform.

• How to Link Multiple Sign-In Methods to One Account

  tutorial

  Let a signed-in user link Google, a guest id and a password to one account on a Parse backend. What the server stores, what expires, what breaks. Measured.

• Android Expense Tracker App With Source Code: Kotlin, Jetpack Compose and Offline Sync That Is Actually Specified [Full Repo]

  tutorial

  A complete Android expense tracker to download and run: Kotlin, Compose, Room, WorkManager and a Parse backend, with an offline sync spec tested cell by cell.

• How to Build a Scalable Game Backend: Leaderboards & Cloud Saves

  tutorial

  Can a general backend-as-a-service run a game's accounts, leaderboards and saves? Built on Parse Server, seeded with a million scores, every query timed.

• Why Vibe-Coded Apps Break: 13 Problems From 130,000 Posts, Ranked, With the Fix for Each

  report

  Why vibe-coded apps break: the 13 problems vibe coders hit most, ranked from annoying to app-killing from 130,000 posts, with the fix for each.

• How to Turn a Gantt Spreadsheet Into a Project Tracker Your Team Can Query [Full Repo]

  tutorial

  Import the schedule, then ask it what is late and what that blocks. Twelve activities imported in 502 ms, four answers in under half a second each. Oct 2026.

• How to Ban and Unban Users in Your App, and Make the Ban Stick [Full Repo]

  tutorial

  A flag and one trigger blocks the next login — and leaves the banned user signed in, able to clear the flag. The three triggers that close both. Sept 2026.

• How to Find the Nearest Driver in an Uber-Style App [Full Repo]

  tutorial

  Store each driver's location and let the database answer who is closest, and how far the trip is. Built and checked in under five seconds, Sept 2026.

• How to Build the Backend for a Flutter App: Login, Data and Push Notifications [Full Repo]

  tutorial

  Accounts, per-user notes and push registration for a Flutter app over REST with package:http, no SDK. Create 440 ms, list 420 ms, measured Sept 2026.

• How to Upload and Serve Images From an App Without S3 [Full Repo]

  tutorial

  Upload user images from a web page with two REST calls to a managed backend and serve them from a CDN URL. 1 MB in 6.8 s, 25 MB accepted. Measured Sept 2026.

• Why Does the API Return 101, 119, 142 or 209? Every Backend Error Code, Reproduced [Full Repo]

  error-guide

  Every error code a backend API returns, reproduced with curl: 101, 119, 141, 142, 202, 203, 206, 209 and more, with HTTP status, cause and fix. Sept 2026.

• Build and Deploy a Node.js REST API in 15 Minutes — Without Owning a Server [Full Code Inside]

  tutorial

  The same Task API two ways: 105 lines of Express you maintain forever, or 24 lines on Back4app. Measured comparison, every command tested August 2026.

• How to Add Authentication to a Web or Flutter App Without Writing an Auth Server [Full Repo]

  tutorial

  Add signup, login, logout and password reset to a web or Flutter app with six REST calls to a managed backend and no auth server. Signup 597 ms, login 245 ms.

• Your Frontend Talks Straight to the Database. Here Is How to Lock It Down [Full Repo]

  tutorial

  Twelve requests from four identities against one class, before and after class-level permissions, an owner ACL from a hook and a role. Measured Sept 2026.