Expo & React Native components vs Last Seen Up

React Native Components & APIs is two things in one app: a catalog of runnable library demos, and a full React Native learning library. All of it works offline. 50 RUNNABLE LIBRARY EXPLORERS Open a library, run its demos, and read the exact source that produced the screen in front of you: • Frameworks & platform — React Native core (RNTester), Expo Components, TanStack Query, TinyBase, Zustand, Legend-State • UI kits & design systems — React Native Paper, Tamagui, HeroUI Native, Gluestack UI, NativeWindUI, Enriched Markdown, Enriched HTML, Bottom Sheet • Graphics & motion — Skia, Reanimated, Lottie, Victory Native XL, Gifted Charts, Mesh Gradient, Glass Effect • Lists, forms & data — FlashList, LegendList, React Hook Form, Formik, SQLite • Native integrations — VisionCamera, Maps, Notifee, Audio API, Gesture Handler, Haptics, Live Photo, Notifications, Action Sheet READ THE SOURCE, NOT A DOC SITE Every demo ships with a built-in source viewer. Tap the code icon on any screen to read the actual TypeScript behind it, switch between files, and copy what you need into your own project. The version shown next to each library is the version the app is genuinely built against. A CURRICULUM, NOT A LINK DUMP 520 lessons across 22 tracks: JavaScript and TypeScript foundations, React 19, the New Architecture, navigation, performance, native modules, testing, security, release engineering, architecture patterns, and building with AI. Every code sample is compiled against the installed React Native 0.86, React 19.2 and Expo 57 — if a sample would not build, the app would not have shipped. INTERVIEW PREPARATION THAT GOES DEEPER THAN A LIST 666 questions with short answers, full explanations, and 1,317 follow-up questions — the ones an interviewer actually asks next, graded across beginner, intermediate and advanced. PRACTICE, NOT JUST READING • Spaced repetition across 430 flashcards and your interview questions, on one schedule — rate how well you recalled it and the card comes back when it should • 36 quizzes, 540 questions, with an explanation behind every answer • 17 cheat sheets, 5 release-day checklists, 11 decision guides and 40 code challenges • A 337-term glossary that appears inline as you read — tap any term without losing your place • Search across lessons, terms, questions, cheat sheets, checklists and quizzes at once EVERYTHING IS OFFLINE The whole library ships inside the app. No account, no sign-in, no network required — on a plane, on the underground, or in a waiting room before the interview. ONE PURCHASE, NO SUBSCRIPTION Every library demo and its source code is free. The learning library opens the first share of every section for free, and a single one-time purchase — pick whatever tier feels fair, from a cup of coffee upward — unlocks every lesson and interview question for good and removes ads. No subscription, nothing expires. WHO IT IS FOR • React Native developers evaluating a library before adding a dependency • Engineers preparing for a mobile interview • Anyone learning React Native who would rather run code than read about it Feedback is genuinely welcome — there is a Send Feedback link in the More tab.

Know the moment it stops answering. Last Seen Up watches your servers, sites, queues and cron jobs, and wakes you when something stops responding. Checks run on our servers around the clock, so the alert reaches you whether or not your phone is awake. WATCH WHAT MATTERS Add a website and it is one monitor, not three. We check that it answers, and we keep an eye on the SSL certificate and the domain registration behind it, so the renewal you forgot is a reminder weeks out instead of an outage on a Saturday. Servers, ports, DNS records and anything that answers a ping are all one tap to add. CATCH THE JOBS THAT DIDN'T RUN A cron job that stops running fails silently. Give it a heartbeat URL to call when it finishes, and if the call never comes we tell you. The alert shows the last several runs at a glance, so a job that has been failing every other night for a week looks different from one that broke tonight. ALERTS BUILT FOR 3AM Alerts arrive as Time Sensitive notifications, so they break through a Focus. Long-press one to see how long it has been down and what failed, then acknowledge or snooze without opening the app. If nobody answers, escalation rings the next person on your list, and the last rung is an actual phone call. WATCH IT UNFOLD An open incident puts a live counter on your Lock Screen and in the Dynamic Island, ticking up until it recovers and then ending with how long it took. Home Screen and Lock Screen widgets keep your worst monitor in view. ON YOUR WRIST The Apple Watch app carries the full roster and lets you acknowledge an incident with your phone in another room. Complications put your fleet's state on the watch face. SEE THE SHAPE OF IT A dashboard for uptime and response times, with how fast a site usually answers and how slow it gets on a bad day. Maintenance windows keep planned work from paging anybody. BUILT NOT TO LIE TO YOU If the app cannot reach our servers it says so plainly rather than showing you a reassuring green screen. Every relative time is measured against server time, not your phone's clock. Status is never colour alone, so it reads correctly on a watch face, in sunlight, and with VoiceOver. FREE TO START Three monitors and everything above, free, with no trial and no card. Pro raises the account to 50 monitors and lets you bring up to 10 people onto the team, each seeing only the monitors you assign them. - iPhone, iPad and Apple Watch - Sign in with Apple, passkeys, or an emailed code - Full VoiceOver and Dynamic Type support Add the first one in about thirty seconds. SUBSCRIPTION Last Seen Up Pro is an auto-renewable subscription, sold monthly at $5.99 or yearly at $59.99. It raises the account to 50 monitors and 10 people on the team, and unlocks nothing else. Payment is charged to your Apple Account on confirming the purchase, and the subscription renews automatically at the then-current price unless it is cancelled at least 24 hours before the period ends. Manage or cancel it in Settings on your iPhone, under your name, then Subscriptions. Privacy policy: https://lastseenup.com/privacy Terms of Use (EULA): https://lastseenup.com/terms