Handy 990
Dev Notes
How we decide, how we measure, and where we got it wrong: first-hand records of survey results, question-bank audits and design trade-offs. Less polished than the technical documents, but every number is real.
Published · 2026-10-29
Your study record got too big for the cloud
One learner's progress suddenly stopped backing up, on their phone and on their computer. It wasn't the network, and nothing had crashed. Their study record had simply grown past the most the cloud will store as a single record, and only by a tiny bit. This post is about how we found it, and what we're doing so it never leaves anyone stuck again.
Read the note →Published · 2026-10-22
How big is a TOEIC app, really? Handy 990 by the numbers: 650,000 lines of code, 28,640 questions, 80,000 audio clips
Handy 990 is exactly 156 days old, counting from the first day code was written. We went through the whole project and counted everything: code, questions, teaching material, pictures, audio, video, change history, releases, articles and design documents. This post lays all the numbers out, explains how each one was counted, takes a detour to explain what actually happens after you tap "Report a problem" inside the app — and tells you which numbers you should not take too seriously.
Read the note →Looking for the full methods and models? See the technical documents →