5 Buck Charlie

Project Overview

5 Buck Charlie is a mobile application backend platform that connects advertisers with users through job postings, advertisements, and news content. As a Backend Developer on this company project, I architected and developed a comprehensive backend system supporting dual user roles (Advertisers and Normal Users), referral point tracking, device ID management, and content distribution. The platform incentivizes user engagement through a referral reward system where both users and advertisers earn points.

The backend handles job posting management, advertisement distribution, news content, referral code generation and tracking, device-based user identification, and a sophisticated points system that rewards both content creators (advertisers) and content consumers (users) for platform engagement.

Key Achievements & Impact

User Types

Device ID

User Tracking

Referral

Points System

Mobile

App Backend

Technical Stack

Django Django REST Framework Python PostgreSQL RESTful APIs JWT Authentication Device ID Tracking Referral System Points Management File Upload Mobile Backend

Backend Development Responsibilities

Dual User Role System: Designed and implemented a comprehensive user management system supporting two distinct user types: Advertisers (who post jobs, advertisements, and news) and Normal Users (who view content and earn referral points). Implemented role-based access control ensuring advertisers can only post content while users can only view and interact.
Job Posting Management: Developed complete job posting system allowing advertisers to create, update, and manage job listings. Implemented job categorization, filtering, search functionality, and expiration management. Built endpoints for job applications and job status tracking.
Advertisement System: Created advertisement management platform where advertisers can post various types of advertisements (banner ads, sponsored content, promotional posts). Implemented ad scheduling, targeting, and performance tracking. Built content moderation and approval workflow.
News Content Management: Developed news posting system allowing advertisers to publish news articles and updates. Implemented content categorization, tagging, and featured news functionality. Built content distribution endpoints for mobile app consumption.
Device ID Tracking System: Implemented device ID-based user identification and tracking system. Each user account is associated with unique device IDs, enabling multi-device support while maintaining user identity. Built device registration, validation, and management endpoints.
Referral Code System: Developed comprehensive referral system where each advertiser gets a unique referral code. Implemented referral code generation, validation, and tracking. Built endpoints for users to enter referral codes and for advertisers to track referral performance.
Points Management System: Created sophisticated points tracking system where users earn referral points for viewing advertisements and engaging with content. Advertisers also earn points when their referral codes are used. Implemented points balance tracking, transaction history, and points redemption functionality.
Content Access Control: Designed permission system ensuring users can view advertisements, jobs, and news while only advertisers can create and manage content. Implemented content visibility rules and access logging for analytics.
User Engagement Tracking: Built analytics system tracking user interactions with advertisements, job views, referral code usage, and points earned. Implemented endpoints for advertisers to view engagement metrics and performance analytics.
Mobile API Optimization: Optimized all API endpoints for mobile app consumption with efficient data serialization, pagination, and caching strategies. Implemented mobile-specific endpoints for push notifications and in-app messaging.

Core Features Implemented

👥 Dual User System

Advertisers: Can post jobs, advertisements, and news content. Normal Users: Can view content, earn referral points, and interact with posts.

💼 Job Posting Platform

Complete job management system with posting, categorization, search, filtering, and application tracking. Advertisers can manage multiple job listings.

📢 Advertisement Management

Advertisement creation, scheduling, targeting, and performance tracking. Support for various ad types including banners, sponsored content, and promotional posts.

📰 News Content System

News posting and distribution system allowing advertisers to publish articles and updates. Features categorization, tagging, and featured content management.

📱 Device ID Tracking

Unique device ID system for user identification and multi-device support. Tracks user activity across devices while maintaining unified account identity.

🎁 Referral Code System

Unique referral codes for each advertiser. Users can enter codes to earn points, and advertisers track referral performance and earn rewards.

⭐ Points Management

Comprehensive points system where users earn points for viewing ads and engaging with content. Advertisers earn points when their referral codes are used.

📊 Analytics & Tracking

User engagement tracking, content performance analytics, referral code usage statistics, and points transaction history for both user types.

Technical Challenges & Solutions

Challenge: Device ID-Based User Management

Problem: Implementing a reliable user identification system using device IDs while supporting multi-device access, preventing duplicate accounts, and maintaining user identity across device changes.

Solution: Created a device management system that associates multiple device IDs with a single user account. Implemented device registration endpoint that validates device IDs and links them to user accounts. Built device validation middleware that checks device ID on each request. Added device history tracking to prevent account duplication while allowing legitimate multi-device access. Implemented device change detection and account migration logic.

Challenge: Referral Code Tracking & Points Distribution

Problem: Tracking referral code usage accurately, preventing code reuse, ensuring fair points distribution to both users and advertisers, and handling concurrent referral code entries.

Solution: Implemented atomic database transactions for referral code processing to prevent race conditions. Created referral code validation system that checks code uniqueness, expiration, and usage limits. Built points distribution logic that awards points to users for entering codes and to advertisers when their codes are used. Added referral transaction tracking with timestamps and user associations. Implemented duplicate prevention by tracking device ID and user combinations for each referral code.

Challenge: Role-Based Content Access Control

Problem: Implementing secure access control ensuring only advertisers can create posts (jobs, ads, news) while users can only view content, with proper permission validation at API level.

Solution: Created custom Django permission classes (`IsAdvertiser`, `IsNormalUser`) that validate user roles before allowing actions. Implemented ViewSet-level permissions that restrict POST/PUT/DELETE operations to advertisers only. Built serializer-level validation that checks user role before processing requests. Added middleware to validate user permissions on content creation endpoints. Ensured all content viewing endpoints are accessible to both user types while creation endpoints are advertiser-exclusive.

Challenge: Points System Integrity

Problem: Maintaining accurate points balances, preventing points manipulation, handling concurrent point transactions, and ensuring fair distribution of referral rewards.

Solution: Implemented database-level constraints and atomic transactions for all points operations. Created points transaction model that logs every points change with timestamp, user, reason, and amount. Built points balance calculation that aggregates transactions rather than storing mutable balance. Added validation to prevent negative balances and ensure points are only awarded for legitimate actions. Implemented idempotent points operations to prevent duplicate point awards from retries or concurrent requests.

Challenge: Content Distribution & Performance

Problem: Efficiently serving jobs, advertisements, and news content to mobile app users with proper filtering, pagination, and performance optimization for large content volumes.

Solution: Implemented efficient database queries using `select_related()` and `prefetch_related()` to minimize database hits. Created pagination system for content endpoints to handle large datasets. Built filtering and search functionality at database level for optimal performance. Implemented caching strategy for frequently accessed content. Added content prioritization logic (featured content, recent posts) to improve user experience. Optimized API responses with selective field serialization to reduce payload size for mobile apps.

Database Architecture

User Model: Extended Django user model with role field (Advertiser/Normal User), device IDs association, points balance, and profile information. Includes referral code for advertisers.
Device Model: Tracks device IDs associated with user accounts, device type, registration timestamp, and last active time for multi-device support.
Job Model: Stores job postings with title, description, category, location, salary, requirements, advertiser reference, posting date, and expiration date.
Advertisement Model: Manages advertisements with type (banner/sponsored/promotional), content, images, target audience, scheduling, and advertiser association.
News Model: Stores news articles with title, content, images, category, tags, featured status, and advertiser reference.
ReferralCode Model: Tracks referral codes with unique code string, advertiser association, creation date, usage count, and expiration date.
PointsTransaction Model: Logs all points transactions with user, amount, transaction type (earned/spent/referred), reason, timestamp, and related referral code if applicable.
UserEngagement Model: Tracks user interactions with content including views, clicks, time spent, and engagement metrics for analytics.

API Endpoints Developed

User Management

POST /api/users/register/ - User registration with role selection
POST /api/users/login/ - User authentication
GET /api/users/profile/ - Get user profile
PUT /api/users/profile/ - Update profile
POST /api/users/device/register/ - Register device ID
GET /api/users/points/ - Get points balance
GET /api/users/points/history/ - Get points transaction history

Job Management

GET /api/jobs/ - List all jobs (users can view)
POST /api/jobs/ - Create job (advertisers only)
GET /api/jobs/{id}/ - Get job details
PUT /api/jobs/{id}/ - Update job (advertiser only)
DELETE /api/jobs/{id}/ - Delete job (advertiser only)
GET /api/jobs/search/ - Search jobs
GET /api/jobs/my/ - Get advertiser's jobs

Advertisement Management

GET /api/advertisements/ - List advertisements
POST /api/advertisements/ - Create advertisement (advertisers only)
GET /api/advertisements/{id}/ - Get advertisement details
POST /api/advertisements/{id}/view/ - Track ad view and award points
GET /api/advertisements/my/ - Get advertiser's ads

News Management

GET /api/news/ - List news articles
POST /api/news/ - Create news post (advertisers only)
GET /api/news/{id}/ - Get news article
GET /api/news/featured/ - Get featured news

Referral System

GET /api/referral/code/ - Get advertiser's referral code
POST /api/referral/enter/ - Enter referral code (users)
GET /api/referral/stats/ - Get referral statistics (advertisers)
GET /api/referral/usage/ - Get referral code usage history

Business Model Implementation

Platform Mechanics

Advertiser Benefits: Advertisers can post jobs, advertisements, and news to reach users. They receive referral codes and earn points when users enter their codes.
User Benefits: Users can view all content (jobs, ads, news) and earn referral points for engagement. Points can be redeemed or accumulated for rewards.
Referral Incentive: Both parties benefit - users get points for entering codes, advertisers get points when their codes are used, creating a viral growth mechanism.
Device-Based Tracking: Device ID system ensures accurate user tracking and prevents abuse while supporting legitimate multi-device usage.

Security & Performance

Role-Based Access Control: Custom permission classes ensure only advertisers can create content while users can view. API-level validation prevents unauthorized actions.
Device ID Validation: Device ID verification on each request ensures user identity and prevents unauthorized access. Device registration requires authentication.
Points System Security: Atomic transactions prevent points manipulation. All points operations are logged and auditable. Balance calculations are transaction-based, not mutable fields.
Database Optimization: Strategic indexing on frequently queried fields (user role, device ID, referral codes, points transactions). Query optimization using select_related and prefetch_related.
Mobile API Optimization: Efficient serialization, pagination, and caching strategies optimized for mobile app consumption. Reduced payload sizes and improved response times.

Project Details

Project: 5 Buck Charlie - Job Posting & Advertisement Platform
Role: Backend Developer
Company: ENIGMATIX
Type: Company Project, Mobile App Backend
Tech Stack: Django, Django REST Framework, Python, PostgreSQL
Key Features: Dual User Roles, Job Posting, Advertisements, News, Device ID Tracking, Referral System, Points Management

Key Achievement

Successfully architected and implemented a comprehensive mobile app backend supporting dual user roles, referral-based engagement system, and device ID tracking. The platform enables advertisers to reach users through job postings and advertisements while incentivizing user engagement through a sophisticated points and referral reward system.

Connect Advertisers with Users Through Referral Rewards