Free Learning Roadmap

How to Become a Backend Engineer

API design, databases, caching, message queues, distributed systems — the server-side half of every product.

Topics
12
Resources
51
Cost
Free
Most resources are free or freemium
Format
Self-paced

1. Language & Runtime

core
A Backend Language, Deeply

Node.js, Python, Go, Java/Kotlin, Rust, C#. Pick one and know its concurrency, memory, and error models.

Async & Concurrency

Event loops, coroutines, goroutines, threads, actor model. Understanding backpressure and cancellation matters more than syntax.

2. API Design

core
REST

Resources, verbs, status codes, versioning, pagination, idempotency. The 90% case for public APIs.

GraphQL

Schema-first design, N+1 problems, DataLoader, persistent queries. Pick GraphQL when aggregating many backends into one client.

gRPC / Protobuf

Schema-first RPC over HTTP/2. The right tool for internal service-to-service.

3. Databases

core
PostgreSQL

The default relational DB. Master indexes, JSONB, transactions, and the query planner.

ORMs vs Raw SQL

SQLAlchemy, Prisma, ActiveRecord, Hibernate. When ORMs help, when they hurt, and how to drop to raw SQL cleanly.

Schema Migrations

Alembic, Flyway, Prisma Migrate, Rails migrations. Zero-downtime migration patterns for production DBs.

NoSQL Options

Redis (cache/queue), MongoDB (document), DynamoDB (key-value at scale), Elasticsearch (search).

4. Distributed Systems

core
Consistency & CAP

Strong vs eventual, linearizability, serializability. Every design interview probes this.

Message Queues

Kafka, RabbitMQ, SQS, NATS. Understand delivery guarantees, ordering, and consumer groups.

5. Caching

core
Cache Patterns

Cache-aside, write-through, write-behind, TTLs, stampede prevention, cache invalidation.

CDN & Edge Caching

CloudFront, Cloudflare, Fastly. HTTP cache-control headers, cache keys, purging.

6. Authentication & Security

core
AuthN vs AuthZ

Sessions, JWTs, OAuth2, OIDC, RBAC vs ABAC. Foundational for every user-facing backend.

OWASP Top 10

SQL injection, XSS, CSRF, SSRF, IDOR — the everyday attack surface for backends.

7. Web Frameworks

core
Framework Deep-dive

FastAPI/Django (Python), Express/Nest (Node), Spring Boot (Java), ASP.NET (C#), Gin/Fiber (Go). Pick and master the idioms.

8. Testing

core
Unit + Integration Tests

Mock/fake external deps at the boundary; integrate with real DBs via testcontainers.

Load & Performance Testing

k6, Locust, JMeter. Test SLOs before shipping, not after the first 500.

9. Observability

core
OpenTelemetry

The vendor-neutral standard. Instrument once, export to Datadog / New Relic / Grafana Cloud / self-hosted.

SLIs, SLOs, Error Budgets

The Google SRE way of defining reliability without perfectionism.

10. Containers & Deployment

recommended
Docker

Multi-stage builds, layer caching, image size hygiene, healthchecks.

Kubernetes Basics

Pods, Deployments, Services, Ingress, ConfigMaps, Secrets. Enough to deploy and debug your own service.

11. Cloud Platforms

recommended
AWS for Backends

EC2, ECS/EKS, RDS, S3, SQS, SNS, Lambda, API Gateway, IAM, VPC. The default enterprise stack.

12. Career & Craft

optional
Reading Open-Source Code

Best free education for a senior backend engineer. Pick one library you use daily, read its source.

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Curated by WhatTNext Ai · methodology · all roadmaps · last updated 2026-07-29