4 min read / ,

PetrolPuppy - Finding the Cheapest Fuel Near You

TLDR An app that shows live fuel prices for Australia on a colour-coded map. The greenest pin is the cheapest. Free for now while in early release, no sign-up.

Fuel is one of those costs you pay over and over without ever really shopping around. The station on your corner might be 20 cents a litre dearer than one two minutes down the road, and most of the time you'd never know. Over a year of filling up two or three times a week, that gap quietly adds up to hundreds of dollars.

So I built PetrolPuppy, a real-time fuel price comparison app for Australia. It shows you live petrol, diesel and LPG prices near you on a map, colour-coded from green (cheapest) to red (dearest), so the best station is obvious at a glance. No reading rows of numbers, no sign-up. It's free for now while it's in early release.

Try it: petrolpuppy.com, or get it on iPhone from the App Store.

The idea

Most fuel apps make you work for the answer. You open them, scroll a list, squint at prices, and try to do the maths on whether the cheaper station is actually worth the detour. I wanted the opposite: open the app, look at the map, and let colour do the thinking. The greenest pin wins.

That single design decision drove everything else. The map is the product. Everything around it (the list, the filters, the station detail) exists to support that one glance.

What it does

  • Live map with price-coloured pins. Every station near you, shaded green to red by current price. The cheapest options jump out instantly.
  • A strict per-fuel-type filter. Search for U95 and you only ever see U95 prices, not U91 dressed up to look cheaper. U91, U95, U98, Diesel, LPG and E10 are all handled separately.
  • Cheapest-nearby, sorted for you. It auto-locates you, sorts every station by current price, and tells you how much you save versus the local average.
  • Station detail with price history. Tap any station to see its recent price trend, so you can tell whether today is a good day to fill up or worth waiting out.
  • Favourite the stations on your route. Star the ones you drive past every day and check them in a single tap.
  • One-tap directions straight into Apple Maps, Google Maps or Waze.
  • Free for now, no account required. It's free while in early release, works in the browser, and installs to your phone.

How it stays accurate

PetrolPuppy doesn't estimate or interpolate prices. Every price shown comes from official fuel-price data, refreshed automatically through the day. When a source is temporarily unavailable, prices are clearly marked as stale rather than silently dropped, so you always see the last known price instead of a blank map. As always, confirm the price at the pump before you fill up.

How it's built

The web app is Next.js 16 (App Router, React Server Components) in TypeScript, with PostgreSQL via Prisma for storage and BullMQ + Redis running the background sync jobs that keep prices fresh. The map is MapLibre GL, charts are Recharts, auth is self-hosted, and the styling is Tailwind CSS. The iPhone app shares the same backend. It's self-hosted on Coolify on a Hetzner box.

The interesting engineering problem wasn't any single piece. It was keeping a constantly-changing dataset fresh and trustworthy without ever showing a user a stale price as if it were live. Sync jobs, staleness flags, and a colour scale that has to stay meaningful as prices move are where most of the real work went.

What's next

Right now PetrolPuppy is live for Australia, on the web and on iPhone. Android is on the way, and the backend is built to extend to more regions over time. For now the focus is doing one country really well: making the cheapest fuel near you something you can find in a single glance.

Give it a go next time you need to fill up: petrolpuppy.com.