Fully personalized courses that build on what you already know, a tutor that reviews your code, and spaced repetition booked into your calendar on day 3, 7 and 18 — with FSRS tracking how well each concept is holding.
Tutor review
Constrain K with keyof T — typos then fail at compile time.
JavaScript & TypeScript
Module 5 of 12
142
Concepts learned
91%
Retention
23
Day streak
Regradia review · Generics
Thu, 8 Oct · Day 3 review · Google Calendar
1885
The year Ebbinghaus first described the spacing effect
3 · 7 · 18
Days after a lesson when your reviews land
15 min
A spaced review session, instead of hours of re-reading
6 tracks
73 modules, from a first script to microservices
Proven by scientists, not invented by us. The spacing effect is one of the most consistently replicated findings in memory research. See the science
Product tour
Follow one topic through Regradia: the tutor teaches it, your progress records it, and your calendar brings it back.
Question
Integer a = 127, b = 127; Integer c = 1000, d = 1000; System.out.println(a == b); // true System.out.println(c == d); // false
127, is the Integer created on demand, or is there a small pre-built array of Integer objects, ready to be handed out by index?Theory
IntegerCache.cache is a pre-built array holding Integer objects for -128 to 127, created once, statically. Autoboxing calls valueOf(), which is just an index lookup, so a and b point at the identical heap object.public static Integer valueOf(int i) { if (i >= IntegerCache.low && i <= IntegerCache.high) return IntegerCache.cache[i + (-IntegerCache.low)]; return new Integer(i); }
c and d: 1000 is outside the range. What does valueOf() do instead, and why does that make == print false?Seal it
127 == 127 is true but 1000 == 1000 is false.Sealed
The one rule
Don't memorise the interview answers. Know the thing underneath them.
How it works
It asks you to write the code, reviews it line by line, then has you explain the idea back cold. A concept is only marked mastered once you can.
A two-minute placement task sets your start. From there your map adds only what you need: a missing foundation, a topic you asked about, a repeat after a slipped review. Every change is explained.
Every concept comes back on day 3, 7 and 18, booked into Google Calendar for you. An FSRS memory model shows how well each one is holding, and your knowledge bank keeps every card, note and transcript.
Fully personalized
Every course is built around what you already know. Start a new track and Regradia skips what you've mastered — so you only spend time on what's new.
Your knowledge carries over
Concepts you learned in one track count in every other — no repeated intro modules.
A placement task sets your start
The tutor grades a short coding task and starts you at the right module.
Lessons adapt as you go
Examples, pace and practice change with your goal and where you struggle.
Your course
Web Dev with React
+ 4 more modules, then the final project
Knowledge map
Everything you learn opens new paths. Your map grows with you — so you always know what you can learn next, and why.
Learned Spring Security → 3 new paths unlocked. OAuth 2.0, JWT and method security are now open — each one builds on what you already know.
The science
Re-reading the same material every day feels productive, but it isn't how memory works. Decades of research on the spacing effect show that reviewing at growing intervals — right as you're about to forget — builds memories that last far longer, in less total time.
Review at the right moment
Every topic you learn comes back on day 3, 7 and 18 — spaced out, not crammed.
Gaps grow as memory strengthens
Each review makes the memory fall more slowly, so the gaps can widen from days to weeks.
Less time, more remembered
A 15-minute spaced session replaces hours of re-reading, and the knowledge stays.
How much you remember
Each dot is a short review — on day 3, 7 and 18 after you learn a topic. Every review resets the curve and makes it fall more slowly. Illustrative.
~1 hour
Time spent studying
~90%
Remembered on day 30
Pathways
Pick one to start. What you learn in it counts towards every other track.
A fraction of a bootcamp or a private tutor — with a review system neither offers.
7 days free · Cancel anytime