Learn to code, with practice after every lesson
126 lessons across 15 tracks, about 35 hours of reading, and 378 multiple-choice questions. Nothing is gated and there is no account. Each lesson names the mistake that most often costs people the interview, because that is where the hours actually go.
The tracks beyond the languages are chosen from our study of 2,411 job postings rather than from preference: AWS appeared in 70% of DevOps roles, Terraform in 51%, and Git and Linux across engineering generally. Data engineering, machine learning, Power BI, cybersecurity and business analysis each pair with a role that has live openings on this site.
Variables and types, Lists and loops…
Variables and the browser, Arrays: map, filter, reduce…
SELECT, WHERE and ORDER BY, GROUP BY and aggregation…
Types, classes and main, Collections and loops…
What the cloud actually is, Regions, availability and why it matters…
Commits, and what they really are, Branches and pull requests…
Moving around the filesystem, Pipes, grep and doing real work…
What a data pipeline actually is, Batch, streaming and where Kafka fits…
What a SOC analyst actually does, Reading logs and triaging an alert…
What a model actually learns, Overfitting, and the metric that matters…
The data model is the whole job, DAX: measures, columns and context…
Vectors, data frames and why R feels different, dplyr and the tidyverse pipeline…
Big O, and why interviewers ask, The four structures that dominate screens…
The funnel, and the numbers that describe it, SEO that survives an algorithm update…
Requirements are decisions, not documents, Process mapping and finding the real problem…
Common questions
Do I need any programming background?
No. Every track starts at its own beginning and assumes nothing. The first lesson in each explains what the thing is before it shows you any syntax.
How is this different from a video course?
You read a short explanation, then immediately do something with it. Each lesson ends in a practice challenge with an expected output and hints you reveal one at a time, and multiple-choice questions that check you understood rather than recognised.
Is it really free?
Yes, and there is no account. All 126 lessons, 386 practice exercises and the auto-graded problems run in your browser.
Which track should I start with?
Python if you lean towards data or backend, JavaScript if you want to see results on a page quickly. If you already code, Git and Linux are the two that most often show up as gaps in interviews, and DSA is what technical screens actually test.
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