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 and the app listens for 3–6 seconds through the phone microphone. 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 confidence percentage. 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, confidence, timestamp) is written to the device's local storage. Features: microphone measurement; a journal of past readings stored locally; a mood chart built from the local journal (last 7 days); multiple cat profiles (name + a chosen illustrated avatar, no photos); a "Talk to your cat" soundboard of 8 cat sounds that are synthesised live with WebAudio (no audio files ship with the app); a "Was that right?" feedback control that nudges the intent profiles on the device only. Monetization: a single auto-renewing weekly subscription called CatLingo PRO, sold through Google Play Billing, product id catlingo_pro_weekly, with a 3-day free trial. The free tier allows 5 microphone readings per day, shows the last 3 journal entries, one cat profile, and locks the mood chart and the per-cat learned 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; the trial must be cancelled at least 24 hours before it ends to avoid being charged. Permissions used: RECORD_AUDIO and MODIFY_AUDIO_SETTINGS (live microphone measurement only, 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.