Your first checkpoint
Walk the free checkpoint end to end — sign in, run, read findings, pass.
The fastest way to understand CloudSynth is to actually run a checkpoint. Here's exactly what happens, end to end.
Open the lesson
A starter set of concepts and projects is free to read in full without an account — browse Concepts or Projects and open any card marked free. Reading needs nothing further; exercise lessons in that set show the full code editor, starter code, and every tab (Editor, Synthesized template, Architecture) with no account required either. One lesson across the whole catalog is also fully verified for free, regardless of which concept it's in — that's the checkpoint this page walks through.
Sign in to run it
Clicking Run synth & validate on a free exercise is the one moment that needs an account — a focused prompt opens right there, offering Google or GitHub sign-in. No card required, and it lands you right back on the same lesson once you're signed in.
Run and read the findings
Your code runs through the four-stage engine (see The four stages). If an assertion fails, its row shows a Reveal hint button — a hand-written nudge, not the answer. Fix your code and run again; failed rows stay visible so you can see exactly what's still wrong.
Not sure where to even start on a task? Running the check against the unfinished starter works too — the failing rows name exactly what's still missing, which can be a faster way in than guessing blind. It's a shortcut worth knowing about, not the intended path: reading "The CDK way" first and reaching for hints only when you're stuck gets you more out of a lesson.
Pass
Once every assertion is green, the checkpoint is complete — recorded server-side the moment the engine confirms it, not when you say so. That completion is real, verified work: the same standard a paying member's progress is held to.