CatLingo is an entertainment app that analyses cat sounds on the device and names the most likely intent (for example "I am hungry", "Pet me", "Open the door"). It is NOT a translator and NOT veterinary advice — this disclaimer appears inside the app and must appear in the legal pages. How it works: the user taps a big microphone button; the app waits up to 20 seconds for a sound, then measures it for 3–6 seconds through the phone microphone, only while the app is on screen. The audio is analysed live in the browser engine (WebAudio FFT + autocorrelation) on the device. Seven measurable features are extracted (length, base frequency, pitch slope, noisiness, spectral brightness, loudness, syllable count) and scored against 12 built-in intent profiles. The nearest profile becomes the result, with a model similarity percentage (the profile's share among the 12), which is not an accuracy score. The same measurement gives the same result; two real meows can differ. The audio itself is NEVER recorded to a file, NEVER stored and NEVER uploaded — it exists only in memory during the measurement and is discarded when the measurement finishes. Only the result (intent name, percentage, timestamp, measured numbers) is written to the device's local storage. Features: microphone measurement; a journal of past readings stored locally, keeping the newest 400 readings per cat, where old readings can be reopened; the user's own short line for an intent, shown as their note; a mood chart and weekly card built from the local journal (last 7 days); shareable result and weekly cards made on the device as images with no audio; multiple cat profiles (name + a chosen illustrated avatar, no photos); a "Talk to your cat" soundboard of 8 cat sounds synthesised live with WebAudio (no audio files ship with the app); a speaking game that turns the length and pitch of the user's syllables into cat sounds, a game and not a translation, not saved; a "Was that right?" feedback control that nudges one shared set of intent profiles on the device only (not a separate model per cat). Monetization: CatLingo PRO, auto-renewing subscriptions sold through Google Play Billing, in weekly, yearly and monthly plans. A plan may include a free trial or a paid introductory period; the length and prices come from Google Play and are shown before the user confirms, so legal pages must not state a fixed price or trial length. The free tier allows 5 microphone readings per day, shows the last 3 journal entries, one cat profile, the soundboard and the speaking game, and locks the mood chart, weekly card and the learning model. There are NO ads and no ad SDK. There is no account, no login, no email collection, no user-generated content upload and no social features. The subscription is managed entirely by Google Play; the app never sees payment details and never runs its own payment processing. Cancellation is done in Google Play > Subscriptions, before the trial, introductory period or current period ends. Permissions used: RECORD_AUDIO and MODIFY_AUDIO_SETTINGS (live microphone measurement and the speaking game, no recording is saved), INTERNET (only to reach Google Play Billing and to fetch a small remote configuration file), VIBRATE (haptic feedback), and com.android.vending.BILLING. The microphone feature is optional — the app is fully usable without granting it by using the built-in synthesised sample sounds. Audience: general audience, cat owners. Not directed at children.