Free interactive career roadmap

Backend Developer Roadmap

A complete six-month beginner-to-intermediate backend engineering roadmap built around Java, Spring Boot and PostgreSQL. Learn by shipping one production-style commerce backend through APIs, data modelling, security, caching, messaging, testing, observability, deployment and system-design decisions. The plan assumes basic programming familiarity and uses mostly official documentation.

6 months duration24 guided weeks10–12 hours per week

Your progress0 / 24 weeks

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01Month 1 — Java and Engineering Foundations

02Month 2 — Spring Boot APIs and Relational Data

03Month 3 — Security, Caching and Deployment

04Month 4 — Reliability, Messaging and Observability

05Month 5 — System Design and Scale

06Month 6 — Portfolio and Backend Interview Readiness

Java and Engineering Foundations

Build dependable Java foundations and learn the workflow used to change, test and explain backend code.

W01

Modern Java FundamentalsUse modern Java syntax confidently enough to express domain rules without hiding behind frameworks.

10–12 hours per week0/5

Learn: Study types, control flow, methods, records, packages and exceptions.Practise: Solve small order, price and inventory exercises with edge cases.Build: Create Money, Product and Order domain types with validation.Verify: Run examples from the command line and explain every public method.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A small Java domain library that creates and prices valid orders.

W02

OOP, Collections and Clean DesignModel business behaviour with cohesive objects and choose collections by access pattern.

10–12 hours per week0/5

Learn: Study classes, interfaces, composition, generics, collections and streams.Practise: Implement lookup, grouping, sorting and totals over realistic order data.Build: Add inventory reservation and order-status rules without a god class.Verify: Write a short note defending collection and object-boundary choices.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Order and inventory services with focused responsibilities and useful collection operations.

W03

Git, Build Tools and Unit TestingMake changes safely and prove important business behaviour remains correct.

10–12 hours per week0/5

Learn: Learn Git branches, Maven lifecycle, dependency management and JUnit structure.Practise: Create focused tests for valid, invalid and boundary cases.Build: Convert the project to Maven and add repeatable unit tests.Verify: Clone into a clean folder and make the build pass with one command.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A Maven project with meaningful commits and a green automated test suite.

W04

Month 1 Project: Order DomainCombine language, modelling and tests into a reviewable backend foundation.

10–12 hours per week0/5

Learn: Review domain invariants, error boundaries and repository structure.Practise: Ask another person to run the project only from the README.Build: Finish create-order, reserve-stock, price-order and cancel-order flows.Verify: Demonstrate one rejected invalid transition and the test that protects it.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Version 1 of the commerce-order platform with tests, README and a two-minute walkthrough.

MONTH 01 MILESTONEA tested command-line order domain with clear objects, validation, Git history and documentation.

Spring Boot APIs and Relational Data

Turn the domain into a well-structured HTTP API backed by PostgreSQL and verified at multiple test levels.

W05

HTTP and Spring Boot RESTTrace an HTTP request through controller, service and response instead of treating annotations as magic.

10–12 hours per week0/5

Learn: Study HTTP methods, status codes, JSON, dependency injection and Spring Boot structure.Practise: Design resource-oriented endpoints and test them with curl or an API client.Build: Expose product and order endpoints with request and response DTOs.Verify: Show correct success and failure status codes for five scenarios.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Validated REST endpoints for products, inventory and orders.

W06

PostgreSQL, SQL and Schema DesignModel transactional data with keys, constraints and queries that reflect real access patterns.

10–12 hours per week0/5

Learn: Study tables, joins, aggregates, constraints, normalisation and transactions.Practise: Write SQL for order history, revenue, low stock and customer summaries.Build: Design Product, Customer, Order, OrderItem and Inventory tables.Verify: Use EXPLAIN on one slow query and justify any index added.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A PostgreSQL schema, seed data and query notebook for the order domain.

W07

Spring Data JPA and TransactionsPersist domain state without leaking ORM behaviour across the application.

10–12 hours per week0/5

Learn: Study entities, repositories, mappings, fetching and transaction boundaries.Practise: Reproduce N+1 or lazy-loading behaviour and correct it deliberately.Build: Connect the API to PostgreSQL and implement atomic order placement.Verify: Force a failure mid-order and prove the transaction rolls back.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A transactional persistence layer with migrations and explicit mappings.

W08

API Validation, Errors and Integration TestsGive clients predictable contracts and catch failures across web, service and database layers.

10–12 hours per week0/5

Learn: Study Bean Validation, exception handlers, test slices and containerised integration tests.Practise: Test malformed bodies, missing records, conflicts and database constraints.Build: Add one error format, request validation and end-to-end API tests.Verify: Run the complete suite against a clean database in CI-like conditions.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Version 2 with stable error contracts, API tests and a reproducible PostgreSQL test environment.

MONTH 02 MILESTONEA documented Order API with migrations, transactions, validation and integration tests.

Security, Caching and Deployment

Protect the API, improve hot paths responsibly and ship the service in a repeatable containerised environment.

W09

Authentication and AuthorizationSeparate identity from permissions and enforce access at the server boundary.

10–12 hours per week0/5

Learn: Study password handling, sessions/tokens, OAuth concepts and role-based authorization.Practise: Write an authorization matrix before implementing checks.Build: Add customer and administrator access rules with Spring Security.Verify: Attempt horizontal and vertical privilege violations and record results.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A complete sign-in flow and server-enforced authorization tests.

W10

API Contracts and EvolutionMake the API easy to consume and safe to change.

10–12 hours per week0/5

Learn: Study OpenAPI, pagination, filtering, idempotency and compatibility.Practise: Review the API from a client developer's perspective.Build: Publish an OpenAPI contract and add pagination plus idempotent order creation.Verify: Run contract examples and document one backward-compatible change.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A versioned, documented API contract with pagination and idempotency behaviour.

W11

Redis and Performance BasicsUse caching only after measuring a repeated expensive read.

10–12 hours per week0/5

Learn: Study Redis data types, expiration, cache-aside and invalidation trade-offs.Practise: Measure uncached and cached product reads under a simple load.Build: Cache product catalogue reads and invalidate them on updates.Verify: Demonstrate stale-data prevention and cache failure fallback.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A measured cache implementation with explicit key, TTL and invalidation rules.

W12

Docker, CI and First DeploymentCreate the same runnable system locally, in CI and in a hosted environment.

10–12 hours per week0/5

Learn: Study images, containers, Compose, configuration and CI workflows.Practise: Run API, PostgreSQL and Redis as a clean multi-service stack.Build: Containerise the service and add build-plus-test automation.Verify: Deploy from a clean commit and verify health, logs and database connectivity.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Version 3 deployed with Docker, CI, environment configuration and runbook.

MONTH 03 MILESTONEA deployed authenticated API with role checks, Redis caching, OpenAPI documentation and CI.

Reliability, Messaging and Observability

Design for repeated requests, failed dependencies, background work and production diagnosis.

W13

Concurrency and Background WorkRecognise shared-state risks and move suitable work outside the request path.

10–12 hours per week0/5

Learn: Study threads, executors, virtual threads, futures and safe concurrency.Practise: Reproduce and fix one race condition in a controlled exercise.Build: Move receipt generation or stock reconciliation into background work.Verify: Test cancellation, timeout and duplicate execution behaviour.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A bounded background workflow with documented concurrency and failure semantics.

W14

Kafka and Event-Driven WorkflowsUse events for decoupling while accepting delivery and ordering realities.

10–12 hours per week0/5

Learn: Study topics, partitions, consumer groups, offsets and delivery guarantees.Practise: Trace duplicate, delayed and out-of-order event scenarios.Build: Publish OrderPlaced events and consume them in a notification component.Verify: Restart the consumer and prove processing resumes without corrupting state.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

An event-driven order notification flow with idempotent consumer logic.

W15

Resilience and External IntegrationsKeep dependency failures from cascading through the application.

10–12 hours per week0/5

Learn: Study timeouts, retries, backoff, circuit breakers and bulkheads.Practise: Simulate slow, unavailable and rate-limited payment responses.Build: Integrate a mock payment API with bounded resilience policies.Verify: Show which failures retry, fail fast or open the circuit and why.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A payment integration with explicit timeouts, retry rules and failure mapping.

W16

Logs, Metrics and Production DiagnosisObserve user-impacting behaviour and debug failures using evidence.

10–12 hours per week0/5

Learn: Study structured logs, correlation IDs, health checks, metrics and traces.Practise: Create dashboards or queries for latency, errors and order throughput.Build: Instrument the critical order path with Actuator and Micrometer.Verify: Diagnose a planted failure using only logs and metrics.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Version 4 with health checks, structured logs, service metrics and a diagnosis note.

MONTH 04 MILESTONEAn observable order workflow using asynchronous events, retries, metrics and tested failure handling.

System Design and Scale

Connect implementation choices to capacity, consistency, data access and service boundaries.

W17

Performance and Database TuningFind bottlenecks with measurements instead of guessing.

10–12 hours per week0/5

Learn: Study query plans, connection pools, pagination and profiling.Practise: Load-test representative read and write paths and capture a baseline.Build: Fix the highest-impact query or application bottleneck.Verify: Compare before-and-after latency, throughput and resource use.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A performance report with reproducible load, bottleneck evidence and measured improvement.

W18

Consistency and Distributed DataChoose correctness boundaries when work spans databases and services.

10–12 hours per week0/5

Learn: Study ACID, isolation, optimistic locking, outbox and eventual consistency.Practise: Model double-submit, overselling and lost-update failures.Build: Add optimistic locking and an outbox-style event publication path.Verify: Demonstrate recovery from a failure between database commit and event delivery.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A consistency design with working protection against one realistic race or dual-write failure.

W19

Service Boundaries and ArchitectureSplit systems only where ownership, scaling or failure isolation justifies the cost.

10–12 hours per week0/5

Learn: Study modular monoliths, microservices trade-offs, sync versus async calls and API gateways.Practise: Draw request, data and failure paths for the current system.Build: Extract one small notification or catalogue boundary without duplicating core data.Verify: Explain why the remaining system should stay together for now.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

An architecture decision record and one justified boundary implemented or simulated.

W20

Cloud Architecture and DeliveryOperate the service with repeatable releases, backups and rollback thinking.

10–12 hours per week0/5

Learn: Study managed compute, databases, secrets, networking and deployment strategies.Practise: Create a threat-and-failure checklist for the hosted system.Build: Automate deployment and document backup, restore and rollback paths.Verify: Perform one rollback or restore drill and record the result.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Version 5 with an architecture diagram, automated release and tested operational procedure.

MONTH 05 MILESTONEA defensible scale plan backed by measurements and one carefully extracted service boundary.

Portfolio and Backend Interview Readiness

Harden the system, communicate its decisions and prepare for practical backend interviews.

W21

Security and Production HardeningRemove avoidable risk before calling the project production-ready.

10–12 hours per week0/5

Learn: Study OWASP web and API risks, secret handling, dependency scanning and least privilege.Practise: Threat-model the highest-value order and admin actions.Build: Fix the most important authorization, validation or configuration gaps.Verify: Run a security checklist and retain evidence of fixes and accepted risks.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A short threat model, hardened configuration and security verification report.

W22

System Design Case StudiesPractise turning requirements into APIs, data models, components and trade-offs.

10–12 hours per week0/5

Learn: Study requirement clarification, capacity estimates, bottlenecks and failure modes.Practise: Design an order system, notification system and rate limiter on paper.Build: Write one complete design using the project as a concrete reference.Verify: Defend data, cache, queue and consistency choices under follow-up questions.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A concise backend design document with requirements, estimates, APIs, data and failure handling.

W23

Coding, SQL and Debugging InterviewsPrepare for the tasks backend candidates are actually asked to perform.

10–12 hours per week0/5

Learn: Review practical data structures, Java behaviour, SQL and debugging workflow.Practise: Complete timed coding, query-writing and broken-API exercises.Build: Create a reusable interview notebook of mistakes and corrected solutions.Verify: Explain complexity, tests and production implications for each solution.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

Three recorded mocks: Java coding, SQL/data modelling and backend debugging.

W24

Final Capstone and Role EvidencePresent one coherent engineering story instead of a pile of disconnected technologies.

10–12 hours per week0/5

Learn: Review architecture, reliability, security, performance and delivery decisions.Practise: Ask a reviewer to run, use and challenge the system.Build: Polish the repository, deployment, demo data, diagrams and case study.Verify: Fix the top three review issues and map evidence to job requirements.Document the decisions, evidence and remaining limitations for this week.

DELIVERABLE

A live commerce backend, public repository, architecture diagram, case study and five-minute walkthrough.

MONTH 06 MILESTONEA production-style flagship backend, evidence-led case study and focused interview portfolio.