Principal Engineer · 16+ years
Helping senior engineers think and design like architects.
I write about system design, mentor engineers moving toward staff and principal, and teach what I've learned the hard way.
Or go deeper: the live cohort ↗
AI Supply Chain: Threat Model Your Agent Toolchain
Your agent tooling has repo access, credentials and auto-update. Audit it before it ships your secrets.
Tue, 11 Aug · 6:30pm London · 30 minutes · Zoom
What engineers say
29+ engineers and colleagues, sharing what changed after we worked together.
“Gazar is very expert in front-end knowledge. He is very kind and patient in helping and guiding without any judgment. Whenever I talk to him, I learn many things. Actually, he shares his updated knowledge in front-end and AI with me. I am very grateful to him for his help without any expectations.”
“Ehsan is a great developer who brings a wealth of experience and skill. He is very self-motivated and can deliver any piece of work, regardless of complexity. Ehsan has a real passion for learning and sharing what he knows with everyone else in the team. He's a real asset to any organization”
“Ehsan gave me really clear and practical advice on my resume and career direction. His feedback helped me focus on what actually matters to recruiters and improve how I present my skills. Super helpful and easy to talk to !!”
More ways to learn
- Self-paced coursesClean Code Mastery free; System Design Mastery and Node.js & TypeScript interview prep premium.Browse courses →
- 1:1 mentorshipCareer, system-design judgment, and the path from senior to staff and principal.See programs →
- Writing & podcastHundreds of deep-dives on architecture, plus the Breakpoint podcast.Read the latest →
Latest writing
Graph Engineering: Every Edge You Draw Takes a Decision Away From the Model
Agent graphs are state machines with a new name on them. The engineering question is not what a node is, it is which routing decisions you take away from the model and which you leave to it. The rule I apply: only draw edges for decisions you can make better in advance than the model can at runtime.
When Your Data Is Really a Graph: Write the Recursive Query First
Some questions cannot be answered by adding one more join, because the number of joins depends on the data rather than on the query. That is the moment your data has become a graph. Here is how to tell, what a graph actually buys you, and the two costs nobody mentions until you are already paying them.
Semantic Caching for AI Requests, Explained Simply
Your users ask the same question in different words, and you pay for every one. A semantic cache answers from meaning instead of exact text. Here is how it works, in plain language, with a working version you can build in an afternoon.
The Algorithms Worth Knowing in Code Review: Cutting Big O Without Being Clever
The small set of algorithm changes that actually come up in code review, each one shown as before and after, with the Big O it removes.
TypeScript Anti-Patterns That Cost You Twice: Build Time, Runtime, and the Interview
The TypeScript patterns I keep deleting in code review, what to write instead, where the cost lands, and the interview question each one turns into.
How I Find Problems Worth Solving
Staff engineers are judged on whether a problem was worth solving, not just whether they solved it. I do not find those problems by thinking hard. I collect them, let them pile up, and wait for the shape.
Popular this week
What other engineers have been reading in the last seven days.
oxlint vs ESLint: Why I Replaced ESLint with oxlint
Replaced ESLint with oxlint in a React TypeScript project and cut lint time from 12 seconds to under one. What I traded away and whether it was worth it.
Lefthook vs Husky: Why I Switched and Never Looked Back
Lefthook replaces Husky and lint-staged with a single Go binary, parallel hook execution, and built-in file filtering. Here is why I switched and kept going.
TypeScript Anti-Patterns That Cost You Twice: Build Time, Runtime, and the Interview
The TypeScript patterns I keep deleting in code review, what to write instead, where the cost lands, and the interview question each one turns into.
How I Find Problems Worth Solving
Staff engineers are judged on whether a problem was worth solving, not just whether they solved it. I do not find those problems by thinking hard. I collect them, let them pile up, and wait for the shape.
SQLZoo SELECT from WORLD: Solutions and Explanations
Worked solutions to every SQLZoo SELECT from WORLD exercise, from basic filtering to population and GDP-per-capita queries, each explained step by step.
Why I Route Every AI Call Through OpenRouter Instead of Direct Endpoints
I migrated gazar.dev off direct Gemini and OpenAI endpoints onto OpenRouter as a single gateway. One key, one request shape, one bill, and switching models is now a string change. Here is what that bought me and what it cost.
Where to start
The deep dives I'd point a senior engineer at first, grouped by topic.
SQL, from SELECT to subqueries
Worked SQLZoo solutions, joins, aggregates, GROUP BY vs HAVING, and subqueries — the queries interviewers actually ask.
9 deep dives · Start reading →
Database performance & scaling
Indexes, query optimisation, sharding, replication and normalization — how to make a database fast and keep it fast.
8 deep dives · Start reading →Modern TypeScript tooling
Why oxlint replaced ESLint, pnpm vs npm, Lefthook vs Husky, and the Rust/Go shift in the frontend toolchain.
6 deep dives · Start reading →
Data structures in TypeScript
Arrays, linked lists, stacks, queues, trees, tries, graphs, heaps and hash tables — implemented and explained in TypeScript.
12 deep dives · Start reading →
Sorting & searching algorithms
Insertion, selection, merge and quick sort, plus binary and substring search — the classic algorithms, step by step.
6 deep dives · Start reading →
Design systems in practice
What a design system really is (per Atlassian), how Dropbox and Netflix build theirs, and how to roll out an internal UI component library.
6 deep dives · Start reading →
Scaling & system architecture
Horizontal vs vertical scaling, capacity estimation, resilience patterns and the architecture principles behind systems that grow.
6 deep dives · Start reading →
X vs Y: engineering trade-offs
Head-to-head breakdowns — oxlint vs ESLint, REST vs GraphQL, SQL vs NoSQL, Svelte/Preact vs React — with the trade-offs that decide it.
12 deep dives · Start reading →