
I've created a free English vocabulary quiz that requires no registration. Answer 20 questions and you'll get an estimate of your vocabulary size and proficiency level. The learning-focused multiple-choice quiz adjusts its difficulty based on your correct and incorrect answers. You can also specify a range tailored to your goals, such as Eiken or TOEIC. Please feel free to try it out first. https://eitanquiz.com/

AI-powered documentation generation tool for developers

All your school calculators in one place: grades, GPA, tests and math.

Viewing is free with no time restrictions, one-time purchase from 100 to 300 yen (including tax), and compatible with iPhone/Android. This is a dictionary app containing 3,020 qualifications and certifications available in Japan.

Turns PDFs, notes, links or YouTube videos into podcasts you can edit and export.

Free Excel practice with interactive browser worksheets

You can test on the spot: "How many more subjects do I need to take for my GPA to reach a certain level?" Simply enter the subject and grade, and your GPA will be calculated automatically (free with ads).

A Japanese-compatible AI text checker that determines the possibility of being written by generative AI in percentage just by pasting an article.

Going to meet someone you like. An English conversation app for beginners who cannot speak English.

Matrix calculations in spare time

Grammar check and translation on the spot

An English learning app with 10,000 conversation phrases. Card-based learning for instant English composition from Japanese to English and translation from English to Japanese, plus passive listening practice. Perfect for those starting to learn English or looking to brush up on their skills. Completely free and no registration required.

Learn Japanese kana and kanji from zero, then chat in Japanese with yokai who reply with furigana.

On an island without letters, reading, puzzles, and tracing practice. A free hiragana learning app that children ages 2-6 can progress through on their own.

A learning app that automatically converts class recordings into transcripts and summaries that become your notes

A free learning app for children with no ads, where you can practice Eiken® Grade 5 vocabulary, listening, and mock exams.

A learning web application for Information Security Management Technician certification that enables studying by navigating between past exam questions, terminology, and step-by-step illustrated diagrams

Your "word age" can be determined by the words you know. A dictionary of 300 words from obsolete terms to modern slang used by young people in the Reiwa era.

A multifunctional matrix calculation app useful for both learning and practical applications, covering everything from inverse matrices and determinants to eigenvalues and row reduction operations.
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Test your VRChat knowledge with 20 questions in 15 minutes. Pass with 75 points or higher and receive a digital certificate and certificate of completion.