Skip to content
Free · Self-paced · No signup required

Complex topics, explained simply

Clear articles and structured courses on system design, microservices, databases, LLM internals, and AI engineering — built so you actually understand, not just memorize.

Pick a learning pathBrowse articles

8

Courses

59

Lessons

376

Articles

Not sure where to start?

Pick the path that matches your goal — every option is free and self-paced.

New to backend?

Follow the Backend Engineer path — databases, caching, messaging, and system design in order.

Start the path
Interview prep?

CAP theorem, load balancing, microservices patterns — everything you need for system design interviews.

View interview path
Prefer reading first?

Start with a popular comparison article — REST vs GraphQL vs gRPC, explained in plain language.

Read the article

Built for understanding, not buzzwords

CoreConcept is a free educational site for backend, system design, and AI engineering. Guides emphasize mechanisms, failure modes, and decision rules — with original diagrams you can study at your own pace. No signup wall. Corrections and topic ideas are welcome via contact; who we are and how we write is on About.

What's New

Latest articles and updates

New
PostgreSQL Table Partitioning vs Sharding: Scaling Guide

As relational databases grow beyond millions to billions of rows, single-table query performance degrades due to massive…

3 min read

New
Vector Search HNSW vs IVFFlat Indexing Mechanics

Approximate Nearest Neighbor (ANN) search is the engine behind Retrieval-Augmented Generation (RAG) and semantic search.…

3 min read

New
ClickHouse vs PostgreSQL: OLAP Columnar vs OLTP Engines

Relational databases like PostgreSQL excel at Online Transaction Processing (OLTP)—handling frequent single-row reads, u…

3 min read

Browse by Topic

Courses and articles grouped by subject

DevOps & LinuxMicroservices & Distributed SystemsAI, LLM & Agentic SystemsDatabases & Data StorageSystem DesignAPIs & SecurityPerformance & CachingWeb DevelopmentEngineering Career Growth

Structured Curriculum

Each course is broken into bite-sized lessons you can complete in one sitting.

Hands-on Learning

Practice with real-world examples and build projects as you learn.

Learning Paths

Follow curated paths for backend, AI, full-stack, and system design interview prep.

Learning Paths

Curated sequences to guide your learning journey

Intermediate~25 hours
Backend Engineer Path

Build a strong backend foundation — databases, caching, inter-service communication, and system design.

View path
Intermediate~11 hours
AI Engineer Path

From RAG pipelines to agentic architectures — understand how AI fits into modern application stacks.

View path
Beginner~8 hours
Full-Stack Developer Path

Start with TypeScript and React, then Next.js and UI systems — the core modern web stack.

View path
Advanced~21 hours
System Design Interview Path

Prepare for system design interviews with fundamentals, patterns, and classic problem walkthroughs.

View path

Featured Courses

Popular courses to get you started

Performance
Intermediate
Caching
From fundamentals to production — caching strategies, eviction policies, invalidation, Redis, CDN caching, and multi-level architectures. Practical patterns and a guided final project you build in your own stack (no bundled starter repo).
~6.5 hours

14 lessons

View Course
Architecture
Intermediate
System Design Fundamentals
Learn how to design scalable, reliable, and maintainable systems — from single servers to distributed architectures used by millions of users.
~5 hours

12 lessons

View Course
Distributed Systems
Intermediate
Communication Between Services
Master how microservices talk to each other — synchronous REST and gRPC, async messaging, event-driven patterns, resilience, and distributed consistency.
~4.5 hours

10 lessons

View Course

Stay in the loop

New courses and articles delivered to your inbox. No spam, unsubscribe any time.