A field guide to software and interface design
Software, made clear.
Understand software and interface design through diagrams you can actually explore.
FOLLOW A WRITE TO DISK
Interactive STEP 1 / 6What do you want to do?
Help me choose →Start with the problem you recognise. You don’t need to know the technical term.
Understand software basics
You can follow code, but the ideas underneath it still feel abstract.
Choose a system design
You need to split responsibilities or explain a design decision to your team.
Understand a slow database
A query is slow, an index seems ignored, or you want to understand how data is stored.
Build with coding agents
You want AI to help ship changes, with checks and people in control.
Prepare for an interview
You want to explain your reasoning, not memorise a list of answers.
Grow as an engineer
You can ship code and want to understand what the next level asks of you.
THE LIBRARY
Follow your curiosity.
Browse by subject, then pick the question that catches your eye.
Start where the writing is
See all 7 paths →PERSISTENCE · 7 / 7 WRITTEN
How a database keeps your data
How a database actually keeps your data, in the order that makes each step explain the next. Seven steps from a row on a page to a deadlock in production.
EXPLORE THE OTHER PATHS
NOT A SCREENSHOT — TRY IT
Insertion order decides the shape.
A drawing can only show one tree. Feed this one values and the shape follows the order you chose — with the height and the best possible height side by side as they come apart.
This tree is close to its best possible shape: a lookup costs at most 3 comparisons for 7 values.
Whole numbers 1–999; up to 18 distinct values. This model compares tree shape, rather than measured search time.
All 5 visualisers →HOW THIS IS WRITTEN
Every claim here is checked before you see it, and the page tells you what against.
Written by Sören Striewski · How this is written →
The picture carries the point
Every mechanism gets a diagram built to show that mechanism, and the prose only covers what the picture cannot. If a topic has no mechanism, it gets a table and a straight answer instead.
Traceable, not paraphrased
Nothing is written from other people's explainers. Technical pages name the documentation, specification or source code they were checked against, and the date. Pages about practice and career name the case they came from instead — a review that went wrong, an estimate that had to be defended — because judgement has no version number. Either way you can go and disagree at the source rather than take it on trust.
Free, and quiet
Every explanation and diagram is free to use without an account.
MAINTENANCE
How current is what you are reading?
Every article carries a last verified date, which means someone re-read it against the current behaviour — not that a typo was fixed. Anything older than six months is queued for review, and new pieces go out on the feed.