From zero to interview-ready
Become the developer who can be trusted with AI-written code.
Callback is a phone app that teaches coding in short daily sessions. You build fundamentals deep enough to read, check, debug and own any code, whoever or whatever wrote it.
Free to learn the fundamentals.
Try one
Predict the output
An AI assistant wrote this to add 1 to an amount typed into a form. Form fields give you text, so here the typed amount is the text "5". What does it print?
let amount = "5";
amount = amount + 1;
console.log(amount);Want one every day? Join the waitlist.
Signature daily review
Review the AI
Find the bug in code an AI wrote, then explain it. The skill every team now needs. Try one:
An AI assistant wrote this to add up the prices in a shopping cart. But it gives only the last price, not the total. Pick the line with the bug.
Learning that sticks
Write real code on your phone, checked by tests as you go, even offline. Spaced review brings back what you are about to forget.
Interview practice from week one
Short coding and explaining drills, so interviews feel like practice you have already done.
Join the waitlist
Be first to try the beta. We will email you when it opens, and rarely otherwise. Free to learn the fundamentals.
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We will email you when the beta opens. You can leave the list at any time.