FlashBlock — Spaced Repetition by Web Inventions

FlashBlock turns your browser into a study gate. When cards are due, every tab is covered by a review session you can't browse past until the queue is clear. When nothing's due, FlashBlock disappears.

Originally built for hiragana practice, it works just as well for vocabulary, definitions, formulas, dates, or anything else that rewards spaced repetition.

Card layouts

• Flip — read the front, click to reveal the back, then mark "I knew it" or "I forgot."
• Typed — type your answer and get instant feedback.
• Multiple choice — the correct answer mixed with your own distractors, reshuffled every time.
• Confidence — for cards that don't suit a quiz: reveal the answer, then mark "Confident" or "Not confident."

Spaced repetition

Twelve intervals, from one minute to one year. Correct answers push a card further out; wrong answers pull it back in. Reviews stay short day to day, and cards you've genuinely learned stop coming back.

Organisation

Group cards by category and tag, each with its own on/off toggle, so you can drill one topic without dragging in the rest. Auto-tags surface cards by layout or by whether they carry audio. Reset progress per card or per category, and cap the batch size so reviews never pile up.

The blocking overlay

The block holds until the queue is clear, with a snooze button (5 minutes to 8 hours) for when you genuinely have to put it off. Open a fresh tab while a session is active and it redirects to the review screen too — there's no escaping through a new tab.

Audio

Optional audio on the front and back of any card, with a manual replay button.

Keyboard-first

Space flips, 1 and 2 grade, 1–4 picks a multiple-choice answer. You shouldn't need the mouse during a review.

Storage and privacy

Everything stays local in your browser. No account, no sync, no analytics, no telemetry, no remote backup. Your cards live on your computer until you choose to export them — the options page has a one-click backup that writes a file you can re-import or carry to another browser.

Permissions

FlashBlock requests access to all sites because the blocking overlay has to inject itself into every tab when cards are due. It does not read, modify, or transmit the content of the pages you visit.