Projects
40 Java backend project ideas for your resume
Portfolio-ready projects from fresher CRUD APIs to staff-level distributed platforms. Each idea includes scope, tech stack, and interview talking points.
Personal Expense Tracker API
Build a REST API where users register, log in, and track daily expenses by category. Supports monthly summaries, budget limits per category, and filtering by date range. A complete portfolio piece demonstrating CRUD, auth, and SQL aggregations.
Beginner · 2–3 weeks
View project guideLibrary Management System
Digital library backend: manage books, members, borrow/return transactions, and fine calculation for overdue returns. Librarian role can add books; members can search catalog and view borrowing history.
Beginner · 2–3 weeks
View project guideStudent Course Registration Portal
Students browse courses, check seat availability, register/drop courses, and view their timetable. Admins manage courses, instructors, and enrollment caps. Enforces prerequisite courses and prevents double registration.
Beginner · 2–3 weeks
View project guideEmployee Directory REST API
HR-style directory API: departments, employees, managers, and org hierarchy. Supports search by name/department, org chart retrieval, and CRUD with audit fields (createdAt, updatedAt).
Beginner · 1–2 weeks
View project guideTask Manager with Categories & Priorities
Personal task API with projects, categories, priorities (LOW/MEDIUM/HIGH), due dates, and status workflow (TODO → IN_PROGRESS → DONE). Filter and sort tasks; mark overdue tasks automatically.
Beginner · 1–2 weeks
View project guideProduct Catalog with Search & Filters
E-commerce style catalog: products, categories, brands, price, stock. Full-text search by name/description, filter by price range and category, sort by price/rating. Admin CRUD for products.
Beginner · 2–3 weeks
View project guideBlog Platform Backend
Authors publish posts with tags, drafts vs published status, and comments. Readers browse published posts, search by tag, and comment (with moderation flag). Slug-based URLs for posts.
Beginner · 2–3 weeks
View project guideEvent RSVP Manager
Create events with date, venue, capacity. Attendees RSVP (YES/NO/MAYBE), waitlist when full, and organizers view attendee lists. Email reminder hook (log only or integrate SendGrid stub).
Beginner · 2 weeks
View project guideRecipe Management API
Store recipes with ingredients (quantity, unit), steps, cuisine type, and prep time. Search by ingredient or cuisine. Users save favorite recipes. Scale ingredient quantities for different serving sizes.
Beginner · 2 weeks
View project guideSmall Shop Inventory Management
Track products, stock levels, suppliers, and stock-in/stock-out movements. Low-stock alerts, movement history audit trail, and simple sales recording that decrements inventory.
Beginner · 2–3 weeks
View project guideMulti-Tenant SaaS Billing Platform
B2B SaaS billing: tenants, subscription plans, usage metering, invoicing, and payment webhook handling. Tenant isolation at DB level, plan upgrades/downgrades, and prorated billing logic.
Advanced · 4–6 weeks
View project guideReal-Time Order Processing with Kafka
Order service publishes OrderCreated events. Inventory, payment, and notification services consume and react. Saga-style flow with compensating actions on payment failure.
Advanced · 4–5 weeks
View project guideE-Commerce Microservices Platform
Decompose e-commerce into catalog, cart, order, user, and payment services behind an API gateway. Service discovery, centralized config, and distributed tracing across services.
Advanced · 5–6 weeks
View project guideBanking Transaction System with ACID Guarantees
Accounts, transfers, double-entry ledger, and balance inquiries. Enforce ACID transfers with pessimistic locking, prevent overdrafts, and maintain immutable transaction log.
Advanced · 3–4 weeks
View project guideMulti-Channel Notification Platform
Unified API to send email, SMS, and push notifications. Template engine, user preferences, delivery status tracking, retry with exponential backoff, and rate limiting per channel.
Advanced · 3–4 weeks
View project guideProduct Search Service with Elasticsearch
Catalog service writes to PostgreSQL; CDC or events sync to Elasticsearch. Search API with facets, autocomplete, fuzzy matching, and relevance tuning.
Advanced · 3–4 weeks
View project guideDistributed Rate Limiter as a Service
Standalone rate limiting microservice using token bucket or sliding window in Redis. REST/gRPC API for other services to check quotas. Per-API-key and per-IP limits with configurable tiers.
Advanced · 2–3 weeks
View project guideFile Storage Service (S3 Abstraction)
Upload/download files with metadata in DB and blobs in S3. Pre-signed URLs, multipart upload, virus scan hook, and access control per file owner.
Advanced · 3 weeks
View project guideAPI Gateway with Auth, Routing & Resilience
Central gateway routing to downstream microservices. JWT validation, request logging, rate limiting, circuit breaker, and request/response transformation.
Advanced · 3–4 weeks
View project guideCI/CD Pipeline for Java Microservices
Multi-module Maven/Gradle repo with 3+ services. Automated build, test, Docker image per service, deploy to Kubernetes staging on merge, manual promote to production.
Advanced · 2–3 weeks
View project guideEvent-Driven Order Fulfillment Platform
End-to-end fulfillment: order placement, warehouse allocation, shipping label generation, tracking updates. Event sourcing for order state, CQRS read models, and chaos testing for consumer failures.
Expert · 6–8 weeks
View project guideMulti-Region Payment Platform
Payment processing with active-passive multi-region setup, idempotent payment APIs, reconciliation with payment provider, and PCI-minded design (no raw card storage).
Expert · 6–8 weeks
View project guideInternal Developer Portal (Platform Engineering)
Service catalog, API documentation aggregation, environment provisioning templates, and deployment status dashboard. Integrates with GitHub and Kubernetes API.
Expert · 5–6 weeks
View project guideCDC Analytics Pipeline
Capture changes from operational PostgreSQL via Debezium → Kafka → stream processing → analytics warehouse (or ClickHouse). Near-real-time dashboards without impacting OLTP.
Expert · 5–6 weeks
View project guideZero-Downtime Database Migration Platform
Tooling and runbooks to migrate from monolith DB to service-owned DBs using expand-contract, dual-write, and verification jobs — demonstrated on a sample schema split.
Expert · 4–5 weeks
View project guideUnified Observability Integration
Instrument 3+ Java microservices with OpenTelemetry traces, metrics, and structured logs. Unified dashboards, SLO definitions, and alert rules with runbooks.
Expert · 3–4 weeks
View project guideIdentity & Access Management Platform
Central auth server issuing OAuth2 tokens, RBAC + ABAC policies, service-to-service mTLS or client credentials, and admin UI for role management.
Expert · 5–6 weeks
View project guideMulti-Vendor Marketplace with Saga Orchestration
Marketplace checkout splits order across vendors. Orchestrated saga: reserve inventory per vendor, charge once, partial failure handling, and split payouts.
Expert · 6–8 weeks
View project guideFeature Flag & Experimentation Platform
Central feature flag service with targeting rules (user segment, percentage rollout), Java SDK for services, audit log, and kill switch API.
Expert · 4–5 weeks
View project guideHybrid Serverless + Containers Workload Platform
Event-triggered Lambda for bursty workloads; ECS Fargate for steady-state APIs. Shared event bus, unified observability, and cost analysis dashboard.
Expert · 5–6 weeks
View project guideRAG-Powered Internal Knowledge Base
Ingest company docs (Markdown/PDF), chunk and embed into vector DB, expose chat API that retrieves relevant context and answers with citations. Admin UI to re-index documents.
Advanced · 4–5 weeks
View project guideAI Code Review Assistant for Pull Requests
GitHub webhook triggers review on PR open. Send diff + team coding standards (via RAG) to LLM. Post inline comments with severity tags. Rate limit and cost tracking per repo.
Advanced · 3–4 weeks
View project guideIntelligent Support Chatbot with Escalation
Customer support bot using RAG on FAQ and ticket history. Confidence scoring routes to human agent with full transcript. Conversation memory per session.
Advanced · 4–5 weeks
View project guideDocument Summarization Pipeline
Batch and on-demand summarization of long documents (reports, contracts). Map-reduce for docs exceeding context window. Store summaries with link to source version.
Advanced · 3 weeks
View project guideSemantic Search over Product Catalog
Natural language product search: 'comfortable running shoes under $100'. Hybrid search combining keyword filters with embedding similarity. Re-rank top results.
Advanced · 3–4 weeks
View project guideAI Resume & Job Description Matcher
Upload resume and JD; extract skills and experience; compute match score with explanation of gaps and strengths. Bias-aware design — score breakdown transparent.
Advanced · 3–4 weeks
View project guideMeeting Notes & Action Items Extractor
Upload meeting transcript (or integrate speech-to-text API). Generate summary, decisions, and action items with assignees and due dates. Export to Jira/Linear stub.
Advanced · 3–4 weeks
View project guideFraud Detection with Rules + ML Hybrid
Real-time transaction scoring: rule engine (velocity, geo mismatch) + ML model score (Drools + exported model or external API). Explainable decline reasons and analyst review queue.
Expert · 5–6 weeks
View project guideNatural Language to SQL Query Assistant
Ask questions in plain English against a known schema; LLM generates read-only SQL; execute against sandbox DB; return results as table/chart spec. Block destructive queries.
Advanced · 3–4 weeks
View project guideAI API Gateway with Cost Controls & Routing
Central gateway for all LLM calls: auth, per-team quotas, prompt versioning, model routing (cheap vs premium), PII scrubbing, and token usage analytics.
Expert · 4–5 weeks
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