Why refreshing your single page app gives a 404
8 min readHow the Web Works
Your routes work until someone reloads or opens a link directly. Here is why the server has never heard of that URL, and how to tell it what to do.
How the web really works.
The concepts every web developer uses but rarely learns.
What is The Missing Level?
Getting started as a developer is well documented. Tutorials, bootcamps, and courses teach you how to build websites and applications. At the other end of the spectrum, books and conference talks explore software architecture, distributed systems, and staff engineering.
The gap is everything in between.
After years of building production web applications, I realized I could ship features confidently while still treating parts of the web as black boxes. I knew how to use HTTP, cookies, DNS, caching, authentication, and browser APIs, but not always why they worked.
That's the missing level.
The Missing Level is where I document that journey. Every article starts with a practical question, breaks down the concepts behind it, and builds mental models in plain English. These aren't beginner tutorials or academic papers they're practical guides for developers who want to better understand the technologies they use every day.
What I write about (The rabbit holes)
Latest articles
Why your API works in Postman but not in the browser
9 min readHow the Web Works
The same request succeeds in Postman and fails in your app. Here is what the browser adds on top, and how to tell which of its rules you broke.
Why your cookie is not being set
8 min readHow the Web Works
Your server sends the header but the browser stores nothing. Here are the reasons a cookie is silently dropped, and how to find which one is yours.
Session vs session cookie vs sessionStorage
8 min readHow the Web Works
Three different things share the word session. Learn what each one stores, who can read it, and exactly what ends it.
How does a database store data on disk? Pages, logs and indexes
11 min readSoftware Engineering
How does a database store data on disk? Learn what pages are, why the write-ahead log exists, how crash recovery works, and what an index physically is.
What is a database? Types, Transactions and Why Files Fail
23 min readSoftware Engineering
What is a database? Learn why plain files stop working, what transactions and constraints actually do, and how a database keeps data correct under load.
What is a server? Types, Hardware, Software and the Cloud
19 min readHow the Web Works
What is a server? Learn how servers work, why the word means hardware or software, what the main server types do, and how machines become the cloud.
Why a server can never trust your browser
14 min readSecurity
Every check you write in the browser can be edited away. Learn where the trust boundary sits and why client-side validation is convenience, not security.
Cookies vs Sessions vs Tokens: How websites keep you logged in
11 min readSecurity
You log in once, yet the website keeps knowing who you are. Learn how sessions, cookies and tokens keep you logged in without resending your password.
How user authentication works: the main methods explained
12 min readSecurity
User authentication is how a website proves you are who you claim to be. Learn the methods, from passwords to passkeys and MFA, and the tradeoffs of each.
Monolith vs microservices, explained with examples
12 min readSoftware Engineering
Monolith or microservices? The real difference is simpler than the debate suggests. See what each one means, with examples, and when to pick which.
Why we needed Node.js
10 min readHistory of the Web
For years Javascript could only run inside the browser. Learn why Node.js was created and how it let Javascript finally run on the server.
Why we needed React
9 min readHistory of the Web
As web apps grew, keeping the interface in sync with the data got hard. Learn why React was created and what it changed about building user interfaces.
Why we needed Single Page Applications (SPAs)
7 min readHistory of the Web
Before single-page applications, every click meant loading a whole new page. Learn why SPAs were created and how they changed the way web apps are built.
Why we needed jQuery
5 min readHistory of the Web
Before browsers behaved the same way, building interactive websites was painful. Learn why jQuery appeared, what it fixed, and why it later declined.
Why we needed Javascript
12 min readHistory of the Web
Before Javascript, websites were little more than static documents. Learn why Javascript was created and the problems it was built to solve.
What happens during a DNS lookup? A step-by-step guide
12 min readHow the Web Works
Before your browser can connect, it must find the site's IP address. Learn how a DNS lookup works step by step, from browser cache to authoritative server.
7 HTTP request headers every developer should understand
12 min readHow the Web Works
Every HTTP request carries headers describing who is asking and what they want. Learn the 7 request headers you will meet most often, with examples.
Why you should check a domain's history before buying it
7 min readHow the Web Works
Domains are secondhand goods. Search engines, browsers and mail servers all keep long memories about names, and you inherit them at checkout.
Why websites can't tell you your password
7 min readSecurity
A well designed website does not know your password, yet it can still check that you typed it right. Learn how password hashing makes that possible.
What happens after you press Enter
6 min readHow the Web Works
DNS, TCP, TLS, HTML parsing, rendering: the journey from typing a URL to seeing the first pixel on screen.