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.
“Working with Ehsan has been a blast! Ehsan has done an excellent job as the JavaScript Developer at Round Table Apps. He is also very attentive to details and creative in creating an engaging experience. I would highly recommend Ehsan as an invaluable asset to any organisation or team.”
“Ehsan consistently delivers the best in company projects on time and to high standards. I have always admired his ability to stay calm and perform under pressure. He is a great asset to the team both on a professional and personal level. I would not hesitate to recommend Ehsan.”
“I've been working with Ehsan in Netbarg. He has always proved to be a results-oriented teammate who has great technical skills. I would like to recommend Ehsan as a key co-worker to whom to trust any critical work.”
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
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.
Everything Is Being Rewritten in Rust. Is It Time You Learned It?
The kernel dropped the experimental label, Cloudflare rewrote its proxy, and your JavaScript build is already Rust underneath. That is the case for learning it. The case against is that the most important TypeScript tool of the decade picked Go. Here is how I read the trade-off, and where I would still not leave TypeScript.
Situational Awareness: The Decade Ahead to AGI by Leopold Aschenbrenner
A short, simple review of Leopold Aschenbrenner essay. He says AI will reach human-level smarts around 2027. Here is what he gets right, what he gets wrong, and what it means for you.
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.
OAuth2 Sequence Diagrams, Demystified
OAuth2 stops being black magic once you draw it. The authorization code flow explained step by step as a sequence diagram, with every token and redirect.
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.
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.
Situational Awareness: The Decade Ahead to AGI by Leopold Aschenbrenner
A short, simple review of Leopold Aschenbrenner essay. He says AI will reach human-level smarts around 2027. Here is what he gets right, what he gets wrong, and what it means for you.
Everything Is Being Rewritten in Rust. Is It Time You Learned It?
The kernel dropped the experimental label, Cloudflare rewrote its proxy, and your JavaScript build is already Rust underneath. That is the case for learning it. The case against is that the most important TypeScript tool of the decade picked Go. Here is how I read the trade-off, and where I would still not leave TypeScript.
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 →