No moat. Still in business.

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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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Runs automated tests against your APIs and websites after each deploy and on a schedule, with alerts on failure.

Since 2016

Uptime and monitoring · Developers

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A lightweight Mac code editor that runs and debugs code in dozens of languages, for programmers who want quick scripts.

One-off payment · Developer tools · Developers

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Fixes the mixed content and insecure content warnings a WordPress site shows after it moves to HTTPS.

Website builders

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Video player for language learners that shows two subtitle tracks at once, generates subtitles and translates them live.

Free · Video and audio · Individuals and families

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Gets and renews free Let's Encrypt SSL certificates on cPanel shared hosting without command line work.

Free plan · Security and passwords

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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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Flash card app for learners to keep their own word lists and practise them with spaced repetition on Apple devices.

Courses and learning · Individuals and families

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Mobile app where learners practise speaking a new language with AI characters and get pronunciation scores.

Since 2024

Courses and learning · Individuals and families

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Ad-free app that teaches children aged 3 to 14 one of 19 languages through listening, speaking and reading along.

Since 2024

Free plan · Courses and learning · Individuals and families

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Browser extension that swaps sentences on the pages you read into the language you are learning, scaled to your level.

Since 2024

Subscription · Courses and learning · Individuals and families

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Desktop app for designing, calling and documenting APIs that keeps an OpenAPI spec in sync, offline with no login.

Since 2024

Free trial · Developer tools · Developers

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Teaches English, Spanish, French and other languages through song lyrics, with spaced repetition for new words.

Since 2024

Courses and learning · Individuals and families

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Native Mac code editor for web and app developers, with Git, debugging, terminal and remote file publishing.

Free trial · Developer tools · Freelancers

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Helps intermediate language learners reach fluency through spoken chats with an AI tutor, corrections and daily articles.

Courses and learning · Individuals and families

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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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Listening drills that help language learners catch spoken numbers, phone numbers and clock times in over two dozen languages.

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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Practise a new language by chatting with AI, tapping words to save them and reviewing them later with spaced repetition.

Since 2025

Free plan · Courses and learning · Individuals and families

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Builds a command line tool for your API from its docs, with binaries, install scripts and updates, so AI agents can use it.

Since 2026

Developer tools · Developers

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Spin up hosted mock servers from OpenAPI, SOAP, GraphQL or gRPC specs so teams can test without the real backend.

Since 2025

Free plan · Developer tools · Developers

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A browser extension for Chinese learners that puts words from your level into English pages, with readings and meanings on hover.

Since 2026

Courses and learning · Individuals and families

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Phone app for learning a language by listening to native podcasts with synced transcripts and tap-to-translate words.

Since 2025

Subscription · Courses and learning · Individuals and families

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A desktop app for developers to inspect RabbitMQ queues, spy on live traffic and replay dead-lettered messages.

Since 2025

One-off payment · Developer tools · Developers

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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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Graded Japanese stories at your JLPT level, with tap-to-define words, grammar notes, audio and flashcards.

Since 2026

Subscription · Courses and learning · Individuals and families

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A Chrome extension that translates X and Reddit posts and quizzes you on new words, for people learning English.

Since 2026

Subscription · Courses and learning · Individuals and families

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Translates words and short phrases with examples and pronunciation, then saves them to a personal list for language learners.

Since 2026

Courses and learning · Individuals and families

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A local desktop editor for writing language courses with lessons and self-marking exercises, plus a free app to study them.

Since 2026

Free · Courses and learning · Creators and writers

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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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Captures full stack session data from production and passes it to coding agents like Claude Code so they can fix bugs.

Since 2025

Developer tools · Developers

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Ties logs and traces from iOS and Android apps to backend services so app teams can trace a user problem to its cause.

Since 2025

Uptime and monitoring · Developers

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Short Spanish stories pitched at the words an A2 to B1 learner already knows, with unknown words brought back for review.

Since 2026

Free plan · Courses and learning · Individuals and families

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An app for practising spoken conversations in 10 languages with an AI partner, then chatting with native speakers with translation.

Since 2026

Free plan · Courses and learning · Individuals and families

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Compares your OpenAPI spec on each pull request and blocks merges that would break the services using your API.

Since 2026

Free plan · Developer tools · Developers

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Terminal AI agent that edits C and C++ code, then runs your build, tests and sanitizers on each change before you see the diff.

Since 2026

Free plan · Developer tools · Developers

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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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Live voice lessons with an AI language tutor that corrects mistakes as you speak and remembers your past sessions.

Since 2026

Free trial · Courses and learning · Individuals and families

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Upload an OpenAPI or Postman file to get a chat agent that lets your users run your software's actions in plain language.

Since 2025

Free plan · Developer tools · Software companies

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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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Language learners listen to free public domain audiobooks while following highlighted text and optional translations.

Free · 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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Learn any of 75 or more languages from almost any starting language, including rare ones, with a school option too.

Free plan · Courses and learning · Individuals and families

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A language learning app for 77 languages where every lesson ends with you saying the sentence aloud and getting feedback.

Since 2026

Free plan · Courses and learning · Individuals and families

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Generates API docs, client libraries in ten languages and an MCP server from your OpenAPI file, plus usage monitoring, for API providers.

Since 2026

Free plan · Developer tools · Developers

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Learn the 2,136 jouyou kanji by grade, with stroke order, components, readings and example words.

Since 2026

Courses and learning · Individuals and families

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Keeps API specs, mock servers, tests and published docs in step from a single spec, for software teams.

Since 2026

Free plan · Developer tools · Developers