Build a Green Finance Feature in 30 Minutes with the GreenCalc API

The EU is spending billions on the Renovation Wave — 35 million buildings to be retrofitted by 2030. France, Germany, Italy, Belgium, and Spain each have their own subsidy programs with different eligibility rules. If you're building a PropTech app, energy audit tool, or renovation marketplace, your users will ask: "How much subsidy can I get?" This tutorial shows you how to answer that question with a single API call. What We're Building A feature that takes a household profile and returns: Which subsidy programs they qualify for Estimated amounts in EUR Net cost after all subsidies We'll use the GreenCalc API — a REST API covering 12 subsidy programs across 5 EU countries. Prerequisites A free sandbox API key (works immediately, no sign-up required) Any HTTP client (we'll show cURL, JavaScript, and Python) Sandbox key for testing: gc_sandbox_000000000000000000000000000000000 Step 1: Check What's Available First, let's see which countries and work types are supported: # List countries