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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Desktop app that lets developers capture, inspect, edit and mock HTTP and HTTPS traffic for debugging and testing.

Since 2019

Developer tools · Developers

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Desktop data analysis app where you ask about your data in plain English and get Python code, charts and notebooks run on your computer.

Since 2017

Data and spreadsheets

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Lets developers share live progress of scripts and jobs through a link, via an API or a tqdm replacement.

Uptime and monitoring · Developers

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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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Point any domain at any URL with automatic HTTPS, path rules and hit analytics, no server to run.

Free plan · 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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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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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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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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Frontend teams can spin up hosted fake REST endpoints, import OpenAPI or Postman files, and fill responses with fake data.

Free plan · Developer tools · Developers

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Spreadsheet that links to databases and files and lets AI write the formulas, Python and charts for you.

Since 2023

Data and spreadsheets

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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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Watch network calls, logs and events from your iOS or Android app live in a browser, and mock API responses while testing.

Developer tools · Developers

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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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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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Developers can mock or proxy HTTP endpoints at shareable public URLs to test against APIs that are not finished yet.

Free · Developer tools · Developers

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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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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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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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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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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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Runs versioned SQL and Python database migrations with dry runs, history checks and rollbacks, for Python teams.

Since 2026

Free plan · Developer tools · Developers

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Watch network calls, logs and events from iOS and Android test devices live, mock responses and share sessions with your team.

Since 2025

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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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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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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Open-source API client that keeps collections as local files synced through Git, for testing REST and WebSocket APIs offline.

Free plan · Developer tools · Developers

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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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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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Pools GPUs and CPUs from many cloud providers and your own servers so developers can run large data jobs in one place.

Since 2026

Developer tools · Developers

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Language learning app where you add the words you need and it builds practice sessions around them, in 20+ languages.

Since 2025

Free · 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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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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Mac app that intercepts HTTP and HTTPS traffic so developers can inspect it, mock endpoints and serve local files as responses.

Free plan · Developer tools · Developers

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Native HTTP debugging proxy for capturing, decrypting and mocking web and mobile app traffic, with an MCP server for AI agents.

Developer tools · Developers

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Deploys apps from a GitHub repo onto a server in your own cloud account, with HTTPS and redeploys on each push.

Since 2026

Free plan · Developer tools · Developers

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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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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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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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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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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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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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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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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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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

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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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Records every AI agent decision in a signed, tamper-evident log so teams can show regulators what their AI did under the EU AI Act.

Since 2026

Free plan · Developer tools · Developers