Finance and accounting decision
currency-converter
A capable technical user can reproduce the core conversion and charting features as a one-week web app using public rate APIs and existing libraries; native App Store features and publisher distribution are the main things you'd give up.
View on the App Store↗Not priced
No pricing page we fetched carried a figure, so there is nothing to compare against. The build side is still real.
$100one-off38 h to build
$0/mo3 h/mo upkeep
No published price to break even against.
Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need - the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship. All currency-converter alternatives, with the arithmetic →
What a replacement has to do
- User requests a currency conversion → app fetches latest rates → apply conversion and show history/trends → allow export/share
What it still won’t have
- Native App Store distribution (push notifications, native widgets)
- In-app purchases and App Store integrated billing
- Polished mobile-native UX and platform-specific integrations
- Any proprietary rate sources the app may use
What remains hard
- Product polish and ongoing maintenance
First-year cost
No published price
currency-converter does not publish a price we could read, so there is nothing to compare against. What building costs is below.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a responsive single-page currency converter using React for the frontend and a small Node/Express server for caching. Use the Frankfurter API (https://github.com/lineofflight/frankfurter) as the primary rates source and implement a fallback using the Swap PHP endpoints or another public source. Core features in scope: 1) fetch and cache latest exchange rates with TTL and fallback; 2) convert amounts between USD and selected currencies; 3) show simple historical trend chart for last 7/30 days; 4) create a one-tap PNG snapshot of the current rate and share/download; 5) basic settings (default currency, update frequency). Out of scope: native App Store packaging, in-app purchases, push notifications, multi-user accounts. Require robust error handling for API failures, input validation, unit and integration tests for rate-fetching and conversion logic, and a Docker-based deployment to a small VPS or static host + serverless cache.
How we checked
How the score was reached
- Build verdict base78
- An open-source build was found+5
- 3 cited sources+3
- 3/3 assessment runs agreed+4
- Evidence score90
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time - so the same evidence always produces the same number.
How scoring works →Cited sources · 3
Every page the run actually retrieved.
- official productDolar App on the App Store
- open sourcelineofflight/frankfurter (currency data API)
- open sourceflorianv/swap (currency conversion library)
Integrity checks
What held up, and what did not.
