No moat. Still in business.

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Make your own flashcard decks and review them on a spaced repetition schedule in the browser.

Since 2015

Free plan · Courses and learning · Individuals and families

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Open-source billing engine that meters usage, runs subscription and hybrid plans, and issues invoices for software firms.

Since 2021

Free · Invoicing and billing · Software companies

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Build hosted or embedded checkout pages to sell products, subscriptions, tickets and services through your own Stripe account.

Since 2018

Free plan · Payments and checkout · Online sellers

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An ecommerce platform with an API for selling products and subscriptions, with custom storefronts and checkout, for online brands.

Since 2021

Free trial · Online shops · Shops and retail

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Helps students sort courses, tasks, class schedules, flashcards and files into colour-coded folders.

Free · Focus and productivity · Individuals and families

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Budgeting app that links bank accounts, flags bills due before payday and lets couples split costs they choose to share.

Free plan · Money and budgeting · Individuals and families

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A note app for desktop and phone that records and transcribes, then answers questions using your own notes.

Since 2026

Notes and knowledge · Individuals and families

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Choose who can see each page on a WordPress site, with teasers, redirects and paywalls for subscription content.

Free plan · Communities and memberships · Creators and writers

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An iPhone app that takes Japanese learners from beginner to fluent with one new sentence per flashcard and spaced review.

Since 2015

Courses and learning · Individuals and families

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A browser extension that saves and highlights words you look up on web pages, then drills them with flashcards.

Since 2020

Free plan · Courses and learning · Individuals and families

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Note app for students that builds flashcards, quizzes and summaries from notes and PDFs with spaced repetition.

Since 2021

Free plan · Courses and learning · Individuals and families

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Students turn class notes or a PDF into a practice test that marks itself and explains each question they got wrong.

Since 2024

Free plan · Courses and learning · Individuals and families

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A study app for students with spaced repetition flashcards, made from notes and PDFs, and scheduled around your calendar.

Free plan · Courses and learning · Individuals and families

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A WooCommerce plugin that lets shops sell subscriptions, repeat deliveries and instalment plans, with dunning and cancellation flows.

Payments and checkout · Online sellers

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Flashcard maker that schedules reviews by spaced repetition, with dictionaries and text to speech for language learners.

Since 2024

Free plan · Courses and learning · Individuals and families

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Flashcard app for iPad and iPhone where students draw, type or add images to cards and review them with spaced repetition.

Since 2024

Courses and learning · Individuals and families

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Flashcard app that uses spaced repetition so learners review hard cards more often, with sync between devices.

Courses and learning · Individuals and families

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An app for learning Japanese with an AI tutor, speaking roleplays, kanji, quizzes and a personal study plan.

Since 2026

Free plan · Courses and learning · Individuals and families

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A language app that translates words offline, saves them to your own tagged word list and helps you review them with flashcards.

Since 2025

Courses and learning · Individuals and families

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Turns notes, PDFs or images into flashcards you can study online, share by link or print.

Since 2025

Free · Courses and learning · Individuals and families

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Turns PDFs and notes into flashcards you can review and edit, then export to Anki, Mochi or SuperMemo.

Since 2026

Subscription · Courses and learning · Individuals and families

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Hover over Chinese text in any Mac app to see pinyin, meanings and sentence breakdowns, and save words as flashcards.

Since 2026

Free plan · Courses and learning · Individuals and families

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A reading app for language learners that imports books, articles and videos, translates words and sends vocabulary to Anki.

Since 2026

Free · Courses and learning · Individuals and families

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A reading and study app that lets you clip from books and papers, link the clips in mind maps and review them as cards.

Courses and learning · Individuals and families

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Paste a YouTube link or upload a transcript and get an Anki flashcard deck made by AI, ready to import.

Since 2025

Free plan · Courses and learning · Individuals and families

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Billing for SaaS and AI companies that handles subscriptions, usage metering, quotes and invoices.

Free plan · Invoicing and billing · Software companies

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Adds recurring billing, trials, split payments and subscription boxes to WooCommerce stores.

Free plan · Payments and checkout · Online sellers

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Learn Japanese or Korean by tapping words in YouTube videos, manga and books, with flashcards that track what you know.

Since 2025

Free plan · Courses and learning · Individuals and families

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Students upload slides or notes and get practice quizzes and spaced-repetition flashcards made from them.

Since 2025

Free plan · Courses and learning · Individuals and families

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Learn to read Arabic with alphabet lessons, graded stories and flashcards that schedule reviews around your memory.

Since 2026

Free plan · Courses and learning · Individuals and families

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Takes payments, subscriptions and usage billing for software makers and handles sales tax worldwide as merchant of record.

Payments and checkout · Developers

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Connect Claude or ChatGPT so they turn what you read into flashcards, then review them on any device.

Since 2026

One-off payment · Courses and learning · Individuals and families

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WordPress plugin for selling physical goods, digital downloads and subscriptions with built in checkout and payment gateways.

Payments and checkout · Online sellers

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A language app where a partner or friend fills in words, audio and sentences for you to study, on iPhone and Android.

Since 2025

Courses and learning · Individuals and families

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Makes subtitles for your video and audio files so language learners can look up words and send them to Anki.

Since 2026

One-off payment · Courses and learning · Individuals and families

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Reads your Anki flashcards aloud through headphones and grades your spoken answers, with an AI tutor for follow-up questions.

Since 2026

Free plan · Courses and learning · Individuals and families

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Takes payments as merchant of record for software and AI products, with subscriptions, usage billing and tax handled.

Since 2025

Invoicing and billing · Developers

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Records lectures and meetings on Mac or iPhone, transcribes them locally and turns them into notes, flashcards and study sheets.

Free · Notes and knowledge · Individuals and families

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A flashcard app that makes study cards from your PDFs, articles and photos and schedules reviews so you remember them.

Since 2026

Free plan · Courses and learning · Individuals and families

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Save new words from what you read or watch, get AI definitions and examples, then review them with FSRS flashcards on Apple devices.

Since 2025

Free plan · Courses and learning · Individuals and families

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Self-hosted billing for web and game hosting firms that automates subscriptions and server setup, with a WHMCS migration tool.

Free · Invoicing and billing · Software companies

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A WooCommerce plugin for selling subscriptions, taking recurring payments and tracking renewals for online stores.

Free plan · Payments and checkout · Online sellers

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Learn English words from books you are reading, with ready-made flashcards, quizzes and a word bank.

Since 2025

Free plan · Courses and learning · Individuals and families

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Acts as merchant of record for software companies, handling subscriptions, usage billing, feature limits and global sales tax.

Since 2026

Pay as you go · Invoicing and billing · Software companies

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Adds usage limits, credits, plans and spend controls on top of Stripe so AI startups can change pricing without rebuilding billing.

Free plan · Payments and checkout · Developers

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WooCommerce plugin for selling subscriptions and memberships, with renewals, members only content and cancellation save offers.

Free plan · Payments and checkout · Online sellers

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Upload your Anki collection and get an emailed report flagging cards with factual errors or weak wording.

Since 2026

Pay as you go · Courses and learning · Individuals and families

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Upload PDFs, Word files or audio and get quizzes, flashcards and summaries to study from, paid with credits.

Since 2024

Pay as you go · Courses and learning · Individuals and families