I’ve been building Obolus as a cross-country payroll and net income comparison API.
The project now supports:
- salary and payroll calculations
- cross-country tax comparison
- OpenAPI
- MCP
- Pipedream
- ChatGPT App integration
The technical challenge is that a simple field like annual_gross does not mean the same thing across countries.
Germany, Switzerland, the US, Austria, Canada or Australia all encode taxes, social contributions, health insurance and payroll deductions differently.
The ChatGPT App is an interesting next layer because it exposes the same calculation engine through a conversational interface.
A user can now ask:
“Where does a €60k salary go furthest across countries?”
and the app can call the underlying tools directly.
For me, this is the most interesting part:
making structured financial calculations usable by both humans and agents.
Check it out here:
https://chatgpt.com/apps/obolus/asdk_app_69e2134f5d088191b9de2030e2796979