SDE & AI @Amazon | Simplifying software engineering, system design, and generative AI | Building Hungry Minds: the newsletter to stay ahead in software 👇

Tell me about the last time you felt growing as a software engineer. Really.

𝙽𝚞𝚕𝚕𝙿𝚘𝚒𝚗𝚝𝚎𝚛𝙴𝚡𝚌𝚎𝚙𝚝𝚒𝚘𝚗? Here's why:

We all face information overload as software engineers. 
There's too much content and too little time.
You have to stay relevant, but it's hard.

Right now, you're either working or taking a break.

You are hoping to get a dopamine shot from scrolling your feed.

You can find:

💡 A practical tip to implement
📚 An inspirational quote
😆 Something funny

And then what?

→ Scroll past it? 
→ Forward it blindly to a friend?
→ Forget about it in the bookmarks?

The harsh truth: nothing.

What you consume passively doesn't make you learn.

How do I know?
It was the same for me for years.

How do you stay updated with AI, stay relevant in the job market, and continuously grow?

That's the problem I set out to solve with Hungry Minds - a free weekly newsletter to help software engineers learn and stay updated, without the noise.

I'm doing that by:

1. Writing to you daily on LinkedIn to 40K+ followers and over 5M impressions last year
2. Compressing 1 week of software deep dives and trends in 1 free newsletter issue
3. Sharing my thoughts and learnings being promoted to SDE II in 1.5y at Amazon

If that sounds interesting, check out Hungry Minds or DM me! I'm always down for a chat.

Save 50+ hours of your week here: 𝗵𝘁𝘁𝗽𝘀://𝗵𝘂𝗻𝗴𝗿𝘆𝗺𝗶𝗻𝗱𝘀.𝗱𝗲𝘃 (6K+ engineers from startups to big tech are reading already)

DISCLAIMER: Opinions expressed are solely my own and do not express the views or opinions of my employer.

My career background:

I'm currently an L5 software engineer at Amazon in Madrid, working on core Search CX and Personalization. 
In 2022/2023, I delivered 2 successful billion-scale projects with multiple teams across different time zones.

I have worked with multiple code languages (although this doesn't make a difference), and with tech stack in the lines of AWS CDK, React applications, scheduling systems, backends with GraphQL, and simple AI applications.

My education background:

- I finished a Master's in Machine Learning and AI with l'Ecole Polytechnique and IPP
- I completed a Master's in Computer Science and Data Science with ESILV Paris
- I got a Master's in business development and marketing with EMLV Paris

Alexandre Zajac

𝗖𝗼𝗱𝗲 𝗱𝗼𝗰𝘂𝗺𝗲𝗻𝘁𝗮𝘁𝗶𝗼𝗻 𝗶𝘀 𝗡𝗢𝗧 𝗔𝗯𝗼𝘂𝘁:


→ One senior gate-keeping all the knowledge. 

Code documentation is ALL about:

→ Sharing knowledge so the whole team knows how the system works.

1-person docs = single point of failure.

Whole-team docs = redundancy + knowledge multiplication.

Remember:
You NEED documentation to manage a system through people and time.


How do you manage docs effectively?


P.S: Documente my personal interview cheatsheet: https://lnkd.in/d_eCGEJR

SDE & AI @Amazon | Building Hungry Minds to 1M+ | Daily Posts on Software Engineering, System Design, and AI ⚡

No alternative text description for this image

10+1 System Design Patterns Every Engineer Should Know in 2026:


___
btw, my personal interview cheatsheet: https://lnkd.in/d_eCGEJR
___


0.💡Load Balancer: 

Distributes incoming traffic across multiple servers to ensure no single server gets overwhelmed.

➡️ Useful when: You're scaling web applications or ensuring high availability.

1.💡CDN (Content Delivery Network):

Caches content at edge locations worldwide, reducing latency by serving users from the nearest node.

➡️ Useful when: You're serving static assets globally or streaming media at scale.

2.💡Message Queue:

Decouples services by letting them communicate asynchronously through a queue (like RabbitMQ or Kafka).

➡️ Useful when: You need reliable communication between microservices or handling traffic spikes.

3.💡Rate Limiter:

Controls the number of requests a user or service can make within a time window.

➡️ Useful when: You're protecting APIs from abuse or managing resource allocation.

4.💡Circuit Breaker:

Prevents cascading failures by stopping requests to a failing service and allowing it time to recover.

➡️ Useful when: You're building resilient microservices that depend on external APIs.

5.💡Database Sharding:

Splits a database into smaller pieces (shards) distributed across multiple servers.

➡️ Useful when: Your database is too large for a single server or you need horizontal scaling.

6.💡Caching Layer:

Stores frequently accessed data in memory (Redis, Memcached) to reduce database load.

➡️ Useful when: You're optimizing read-heavy applications or reducing latency.

7.💡API Gateway:

A single entry point that handles routing, authentication, and rate limiting for all your microservices.

➡️ Useful when: You're managing multiple services and need centralized control.

8.💡Reverse Proxy:

Sits in front of servers and forwards client requests, adding security, caching, and load balancing.

➡️ Useful when: You need SSL termination, compression, or hiding server architecture.

9.💡Event-Driven Architecture:

Services react to events rather than direct calls, enabling loose coupling and real-time processing.

➡️ Useful when: Building real-time analytics, notifications, or audit logging systems.

10.💡CQRS:

Separates read and write operations into different models, optimizing each for its specific purpose.

➡️ Useful when: You have complex domains with different read/write performance needs.


What did I miss?

You are what you eat.

10 brain foods to grow as an engineer:


0. Why Clock Synchronization Makes Engineers Lose Sleep:
► https://lnkd.in/gkDbWARS

1. How ChatGPT Actually Stays on Track (by Neo):
► https://lnkd.in/ggNMHDuV

2. How to Build Internal AI Agents That Actually Work:
► https://lnkd.in/gkJKyQnm

3. Scaling LLMs to Larger Codebases:
► https://lnkd.in/gWwfibJQ

4. Connection Pooling Finally Explained in 6 Minutes (by Nikki):
► https://lnkd.in/gkx6eNSG

5. 5 Engineering Dogmas It's Time to Retire (by Anton):
► https://lnkd.in/gYTdTmap

6. The System That Eliminates Interruptions for 10x Engineers (by Francisco):
► https://lnkd.in/g65_i6jf

7. Why Logging Sucks (And Everyone Knows It):
► https://loggingsucks.com/

8. Internal Dev Tooling at Meta (from Gergely):
► https://lnkd.in/g_A_BxFd

9. The Future of Software Development Is Software Developers:
► https://lnkd.in/gvzpK2CM


I am packaging the other deep dives and trends in today's issue of Hungry Minds.

Join 50,001+ software engineers from big tech to startups here: https://lnkd.in/dkJiiBnf


What are you reading this week?


#softwareengineering #systemdesign #programming

Author of System Design Newsletter (37K+ Subscribers)

My mission is to help you become good at system design

My portfolio:
→ I'm writing a weekly newsletter about system design
→ I've 10+ years of software engineering experience
→ I've worked at startups and big companies
→ I've mentored many engineers

My results:
→ 100,000+ software engineers learning system design through my newsletter

My newsletter:
→ newsletter.systemdesign.one/subscribe

Neo K.

If you want to become good at system design,
then learn these 12 case studies (not kidding):


1 How ChatGPT Apps Work:
↳ https://lnkd.in/eZpyaUbu

2 How YouTube Works:
↳ https://lnkd.in/e7q9F4Sg

3 How Google Docs Works:
↳ https://lnkd.in/ehPNA7Az

4 How Kafka Works:
↳ https://lnkd.in/eTtVAjTg

5 How WhatsApp Works:
↳ https://lnkd.in/eU2fswMi

6 How Airbnb Works:
↳ https://lnkd.in/dGVfstQM

7 How Spotify Works:
↳ https://lnkd.in/eGbWVeNW

8 How Slack Works:
↳ https://lnkd.in/eATMDjrK

9 How Reddit Works:
↳ https://lnkd.in/egmm_P7a

10 How Bluesky Works:
↳ https://lnkd.in/eEhB8V_k

11 How Twitter Timeline Works:
↳ https://lnkd.in/eniXMPfU

12 How Uber Computes ETA:
↳ https://lnkd.in/eVKV2ePC

What else should make this list?

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers right now:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later & repost to help other software engineers ace system design.
👤 Follow Neo Kim + turn on notifications.

Neo Kim

I Teach You System Design • 0.5M+ Audience

If you want to become a 10x software engineer
(in 2026), read these 10 books:


1. The Pragmatic Programmer
2. Designing Data-Intensive Applications
3. The Mythical Man-Month
4. Refactoring
5. Software Architecture: The Hard Parts
6. Working Effectively with Legacy Code
7. Database Internals
8. A Philosophy of Software Design
9. Clean Code
10. Why Programs Fail

What else should make this list?

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers right now:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later & repost it to help others become 10x software engineers.
👤 Follow Neo Kim + turn on notifications.

If I had to set up an API,
here are 6 protocols I'd consider:


1 REST (Representational State Transfer)
↳ A stateless, resource-based API protocol using standard HTTP methods
↳ Best for: CRUD operations in web and mobile apps
↳ Risk: over-fetch or under-fetch data because of fixed endpoints

——

2 gRPC (Google Remote Procedure Call)
↳ A high-performance, contract-based protocol using a binary format
↳ Best for: internal microservices communication
↳ Risk: limited browser support

——

3 GraphQL
↳ An API query language for clients to request specific data
↳ Best for: frontend-heavy apps with complex data fetching needs and faster response needs
↳ Risk: performance issues from overly flexible queries

——

4 SOAP (Simple Object Access Protocol)
↳ A protocol using XML for messaging with strict standards
↳ Best for: enterprise applications that need high security
↳ Risk: verbose & complex because of XML specifications

——

5 WebSockets
↳ A bidirectional, real-time protocol over a persistent TCP connection
↳ Best for: real-time apps, such as chat or sports updates
↳ Risk: extra logic needed to handle connection states and reconnections

——

6 MQTT (Message Queuing Telemetry Transport)
↳ A lightweight, publish-subscribe protocol
↳ Best for: IoT, sensor devices
↳ Risk: complex queries and large payloads may not work well

(What else should make this list?)

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later and repost it to help others learn system design.
👤 Follow Neo Kim + turn on notifications.

If you're serious about SYSTEM DESIGN (in 2026),
learn these 12 case studies:


1. How Google Docs Works
↳ https://lnkd.in/ehPNA7Az

2. How Spotify Works
↳ https://lnkd.in/eGbWVeNW

3. How Reddit Works
↳ https://lnkd.in/egmm_P7a

4. How Bluesky Works
↳ https://lnkd.in/eEhB8V_k

5. How ChatGPT Works
↳ https://lnkd.in/eSd6fS7n

6. How Kafka Works
↳ https://lnkd.in/eTtVAjTg

7. How Slack Works
↳ https://lnkd.in/eATMDjrK

8. How Meta Handles 11.5M Serverless Function Calls per Second:
↳ https://lnkd.in/eNyYKCQD

9. How Uber Finds Nearby Drivers
↳ https://lnkd.in/eeqH9Hjh

10. How Twitter Timeline Works
↳ https://lnkd.in/eniXMPfU

11. How YouTube Was Able to Support 2.49 Billion Users With MySQL
↳ https://lnkd.in/efmJw4Dx

12 How to Scale an App to 10 Million Users on AWS
↳ https://lnkd.in/eU736g9Q

(What else should make this list?)

——

👋 PS - Want my System Design Playbook for free?

Join my newsletter with 200K+ software engineers:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later, and repost it to help others master system design.
👤 Follow Neo Kim + turn on notifications.

12 System Design Case Studies for Software Engineers

If you want to get started with SYSTEM DESIGN
(in 2026), learn these 20 concepts:


1 How Idempotent API Works
↳ https://lnkd.in/erMkqwq4

2 Saga Design Pattern
↳ https://lnkd.in/eFXC4-aJ

3 Redis Use Cases
↳ https://lnkd.in/ekJMjMG3

4 How JWT Works
↳ https://lnkd.in/ek9_BTUc

5 How RPC Actually Works
↳ https://lnkd.in/eScZS9F5

6 How Consistent Hashing Works
↳ https://lnkd.in/eUP9DbCg

7 How Service Discovery Works
↳ https://lnkd.in/eCYYwQfU

8 Monolith vs Microservices Architecture
↳ https://lnkd.in/e3EBtg_v

9 What Happens When You Type a URL Into Your Browser
↳ https://lnkd.in/eusuDn5z

10 Microservices Lessons From Netflix
↳ https://lnkd.in/eZSM3CRB

11 Frontend System Design 101
↳ https://lnkd.in/ehHuXpjx

12 How Websockets Work
↳ https://lnkd.in/euHDJUfH

13 How Bloom Filters Works
↳ https://lnkd.in/e2duES7s

14 How Databases Keep Passwords Securely
↳ https://lnkd.in/edd8-N5k

15 How Does HTTPS Work
↳ https://lnkd.in/enM_pZYd

16 Modular Monolith Architecture
↳ https://lnkd.in/edUqkCKR

17 API Design Best Practices
↳ https://lnkd.in/eUEFzEC8

18 How DNS Works
↳ https://lnkd.in/e8H3EGvp

19 System Design 101
↳ https://lnkd.in/eijR9-aG

20 API Versioning - A Deep Dive
↳ https://lnkd.in/eg_fmBhu

(What else should make this list?)

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers:
→ ​​https://lnkd.in/ehTrcyak

———

💾 Save this for later, and repost to help others learn system design.
👤 Follow Neo Kim + turn on notifications.

20 System Design Concepts for Software Engineers

If you want to boost your software engineering career,
star + bookmark these 12 GitHub repos:


1 Vision Agent
↳ https://lnkd.in/e-ZHJTqc

2 System design
↳ https://lnkd.in/eKATU6QV

3 Public APIs
↳ https://lnkd.in/epWSyzqs

4 Tech interview handbook
↳ https://lnkd.in/e7EjsJNF

5 Coding interview university
↳ https://lnkd.in/evJSNCPE

6 Engineering leadership
↳ https://lnkd.in/ePCzV3zF

7 Freecodecamp
↳ https://lnkd.in/e_4pA8xV

8 Developer roadmaps
↳ https://lnkd.in/e9MuB_Yg

9 Path to senior engineer handbook
↳ https://lnkd.in/exkJCxVi

10 Free programming books
↳ https://lnkd.in/eXAzAJ3M

11 Build your own x
↳ https://lnkd.in/ekZQbTPz

12 Awesome lists
↳ https://lnkd.in/eczWuVG2

Remember, star + bookmark these repos right now.

(What else would you add?)

——

💾 Save this for later & repost to help others become good software engineers.
👤 Follow Neo Kim + turn on notifications.

I struggled with git
until I learned these 19 commands:


1 git add
↳ It lets you add changes from the working directory into the staging area.

2 git commit
↳ It lets you save a snapshot of currently staged changes in the local repository, with a message.

3 git push
↳ It lets you upload commited changes from the local repository to a remote repository.

4 git fetch
↳ It lets you download changes from a remote repository, without applying them locally.

5 git merge
↳ It lets you combine changes from one branch into another.

6 git pull
↳ It lets you fetch and then merge changes from a remote repository into the local branch.

7 git diff
↳ It lets you see the changes not staged or commited yet.

8 git diff HEAD
↳ It lets you see changes between the current working directory and the latest commit.

9 git status
↳ It shows you the current state of the working directory and staging area.

10 git branch
↳ It lets you see all local branches.

11 git log
↳ It shows you commits in the current branch with extra details.

12 git checkout
↳ It lets you create a branch or switch between branches.

13 git stash
↳ It lets you temporarily save uncommitted changes and apply them later.

14 git rebase
↳ It lets you apply commits from one branch to another.

15 git reset
↳ It lets you undo changes in the working directory and move back to a specific commit.

16 git revert
↳ It lets you undo changes by creating a new commit.

17 git bisect
↳ It lets you narrow down bugs quickly.

18 git cherry pick
↳ It lets you apply commits from one branch to another.

19 git init
↳ It lets you create an empty repository.

What else would you add?

———

👋 PS - AI Upskilling for Software Engineers

In 2025 alone, the tech industry has already laid off over 200,000 professionals.
Yet nearly 750,000 AI-related jobs remain open, offering a 56% wage premium.

The message is clear:

The gap between "traditional" software engineering and AI engineering is widening.

Which side of the gap are you on?

You want to upskill, but you are overwhelmed by the speed of AI advances.
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———

💾 Save this for later and repost to help other software engineers learn git.
👤 Follow Neo Kim + turn on notifications.

15 heuristics that will help you
pass system design interviews:


1. Latency + Global → CDN
↳ Deliver data from edge servers to reduce latency

2. Read + Bottleneck → Cache
↳ Store frequent reads in cache to reduce database load

3. Write + Spike → Queue
↳ Buffer writes for asynchronous processing during traffic spikes

4. Distributed + Transaction → Saga
↳ Handle multi-service transactions with compensating steps

5. ACID + Relational → SQL
↳ Use a SQL database for strong consistency and transactional integrity

6. Flexible + Scale → NoSQL
↳ Use NoSQL for schema flexibility and horizontal scalability

7. SQL + Scale → Shard DB
↳ Federate and partition data across shards to scale effectively

8. Load + Growth → Scale Out
↳ Add servers to handle extra traffic

9. Traffic + Reliability → Load Balance
↳ Distribute requests evenly for performance

10. Core + Failure → Redundancy
↳ Replicate core services to avoid single points of failure

11. Durability + Faults → Replication
↳ Replicate data for availability and recovery

12. Requests + Spike → Throttle
↳ Limit excessive requests to prevent server overload

13. Load + Spike → Autoscale
↳ Add or remove server capacity automatically to handle changing load

14. Realtime + Updates → WebSockets
↳ Use WebSockets for live, bidirectional communication

15. Retry + Safety → Idempotent
↳ Make operations safe to retry without side effects using idempotency

(What else should make this list?)

Remember, these are just heuristics.
The right solution depends on the requirements.

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later, and repost it to help others pass job interviews.
👤 Follow Neo Kim + turn on notifications.

15 System Design Heuristics for Software Engineers

If I had to deploy code,
here are 5 patterns I'd consider:

1 Big Bang
↳ Deploy on all servers at once, replacing the old version.

2 Rolling
↳ Slowly update servers one batch at a time.

3 Blue Green
↳ Maintain 2 environments and switch traffic between them.

4 Canary
↳ Deploy to a few users first, and slowly increase traffic with monitoring.

5 Feature Toggle
↳ Hide new features behind conditional code logic.

What else should make this list?

——

👋 PS - Want to become an AI Engineer in 2026?

It’s one of LinkedIn’s fastest growing jobs
with salaries from $180K–$350K.

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and credentials to lead AI initiatives.

Cohort starts February 2.

Learn more & enroll right now:
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———

💾 Save this for later & repost to help software engineers learn how deployment works.

5 Deployment Patterns Explained for Software Engineers

10 VS Code extensions to 10x your productivity:


1 Peacock
↳It lets you change the color of VScode based on the project; useful when working on many projects at once.

2 GitLens
↳It lets you get the most out of git inside VScode.

3 Prettier
↳It automatically formats the code for consistent styling.

4 Live Share
↳It lets you do pair programming & debugging sessions remotely.

5 Docker
↳It lets you create, manage & debug containerized apps.

6 REST Client
↳It gives you a REST client inside VScode.

7 Live Server
↳It lets you run a local dev server with live reload.

8 Better Comments
↳It helps you write good code comments.

9 Code Spell Checker
↳It lets you catch spelling mistakes in code & improve readability.

10 Code Runner
↳It lets you run code snippets in many languages.

(What else would you add?)

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers right now:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later and repost it to help others become 10x software engineers.
👤 Follow Neo Kim + turn on notifications.

10 VS Code Extensions for Software Engineers

If you're just getting started with API design,
read this:


An API is a set of rules that allows different services to talk with each other.

What else would you add?

——

👋 PS - Want my System Design Playbook for FREE?

Join my newsletter with 200K+ software engineers right now:
→ https://lnkd.in/ehTrcyak

———

💾 Save this for later and repost it to help others learn API design.
👤 Follow Neo Kim + turn on notifications.

20 API Design Concepts for Software Engineers

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Neo K.

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taplio

The Battle

Alexandre Zajac

Neo K.

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Posts

Engagements

Likes

Performance Score.css-goub6s{font-size:var(--chakra-fontSizes-md);font-weight:500;color:var(--chakra-colors-gray-600);display:block;margin-top:var(--chakra-space-1);}Alexandre Zajac's LinkedIn Performance

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