Fundamentals.
Built.
Shipped.
Learn how data and AI systems actually work, from first principles. Then prove it by shipping working code. Every lesson, video, episode and problem is open.
9 lessons40 problems0 videos0 episodes0 paywalls
From the bit up
Storage, indexes, embeddings and agents, explained from the layer below so the next tool change doesn't reset you.
Practice that runs
Real problems with real tests. You write the code, your browser runs it, and you see exactly what broke.
Shipped, not memorized
Every lesson ends with something working. That's the proof that holds up in interviews and on the job.
Pick a door
Tracks that read like a book. Every lesson ends with something shipped.
SQL and Python problems with real tests, running in your browser.
Videos grouped the way you study: in order, basics to advanced.
The Build Log. Conversations about how systems actually get built.
Start with a problem
Count orders per day with a row for every calendar day, including days with no orders.
A fixed-size cache that evicts the least recently used key, in O(1) per operation.
Read length-prefixed, checksummed records from raw bytes and stop cleanly at a torn or corrupt tail.
New this week
Before indexes and query planners, there's an append-only file. Once you see it, replication and recovery stop being magic.
Twenty videos from install to agents in CI. The folder is set up; videos land here as they publish.
Conversations and audio deep-dives on how data and AI systems get built. Every two weeks.
Ayan Putatunda
Staff Data Engineer with 13+ years in data engineering, now working on AI platforms. BuiltFromBits is where I teach the fundamentals I wish I'd learned first, and ship the code to prove them.
One letter a week
One fundamental, one problem to practice, and what I shipped. Unsubscribe anytime.
Questions
What is BuiltFromBits?
A place to learn how data and AI systems work from the layer below: storage, indexes, SQL engines, pipelines, embeddings and agents. You read or watch the idea, then prove it by shipping code that passes real tests.
Who is it for?
Self-taught developers and career-switchers who want the layer below the tool, CS students who want real data-systems practice, and working data and ML engineers preparing for AI-era technical interviews.
Do I need an account?
No. Everything is open. Your progress is saved in this browser. Optional sign-in to sync across devices comes later.
How does the code run?
In your browser. SQL runs on DuckDB compiled to WebAssembly, Python on Pyodide. Nothing you type is sent to a server.
How often is new material added?
One topic a week: a video, a lesson, a post and a practice problem, published here first and linked to each other.