WattWize

Know what you consume. Control what you spend. WattWize turns the chaos of household energy into clear numbers you can act on. Built by the Positive Promises team, WattWize is an offline-first calculator, appliance library, and AI energy advisor that runs entirely on your phone — no signup, no ads, no telemetry resale. WHAT YOU CAN DO • Build a real appliance library. Add every device in your home with name, brand, model, rated wattage, typical hours of use, quantity, and room. WattWize calculates per-appliance kWh, monthly cost, and CO₂ estimate using your local currency and tariff. • Compare household scenarios. Swap a fridge for a more efficient one, run the dishwasher off-peak, or replace incandescent bulbs with LEDs — see the monthly and yearly delta instantly, line by line. • Plan a solar installation. Enter your system capacity, panel count, roof area, orientation, and city. WattWize estimates annual yield and the years to recover your install cost based on your current tariff. • Connect a Matter smart plug. Discover Matter-over-Wi-Fi or Matter-over-Bluetooth plugs on your local network, label them, and let WattWize verify which ones report their measurements honestly before you trust the numbers. • Snap a rating plate. Point your camera at the back of an appliance and WattWize reads the volts, amps, watts, and model number automatically using on-device text recognition. No image is sent to Google. • Talk to your numbers. Voice input fills wattage, hours, and notes hands-free. Audio is processed on-device and never recorded or transmitted. OFFLINE-FIRST AI WattWize ships with a 2.5 GB on-device large language model (Gemma 4 E2B). Once downloaded, every prompt and every response stays on your phone — no cloud calls, no data sharing. The model can be removed at any time from Settings. If you prefer not to install it, a free cloud fallback parses rating plates through OpenRouter's vision cascade — and you can disable even that in Settings. DESIGNED FOR PRIVACY • No third-party analytics — no Firebase, no Google Analytics, no Mixpanel, no Segment. • No Google Advertising ID, no Android ID, no persistent device identifier for advertising. • Account data is isolated per user by Supabase Row-Level Security; appliance photos live under unguessable UUIDs. • We never sell or rent your data. • Crash reports use Sentry, processed in the EU (Frankfurt). HTTP bodies, cookies, and authorization headers are stripped before any event leaves your device. • The full privacy policy is published at privacypolicy.positivepromises.org and is reachable from inside the app. BUILT FOR REAL HOUSEHOLDS • Currency, tariff, and country presets for Nigeria, the UK, the US, the EU, India, and more. • Multi-member households with named rooms and shared libraries. • Household, library, and per-appliance data syncs across your devices through Supabase. • Anonymous mode — use every feature without an account; upgrade to a named account any time to enable cross-device sync. • Export to PDF and CSV with one tap. • Light and dark themes that respect your system setting. OPEN STANDARDS, NO LOCK-IN WattWize is a Capacitor + Next.js application built on open web standards. Your library data is yours; you can request an export or full deletion at any time from Settings or by emailing [email protected]. What you'll love: • Honest numbers — every calculation is deterministic and visible. • Honest data — see exactly what leaves your phone, in plain English. • Honest price — one purchase, no subscription, no in-app upsells.