Data Sources

Numbeo is the largest crowd-sourced cost-of-living database, covering ~10,000 cities worldwide with line-item prices (rent, groceries, restaurants, transport, utilities, childcare) contributed by local residents.

CostAPI ingests the Numbeo price baskets for city-level comparisons and normalises them against a common reference basket so that two arbitrary cities can be compared consistently. Crowd-sourced data carries sample-size caveats — we surface sample_size and last_updated on every price entry so you can gate on statistical reliability.

Expatistan publishes a curated cost-of-living index for expatriates covering ~2,000 cities. The methodology is similar to Numbeo but uses a smaller, more consistent basket focused on expat household expenses.

CostAPI uses Expatistan as a secondary signal for city comparisons — where Numbeo and Expatistan disagree significantly we flag the entry in the response metadata so callers can decide which source to trust for their use case.

The US Bureau of Economic Analysis publishes Regional Price Parities — index values that quantify how expensive each metro is relative to the national average (100 = US mean). RPP is released annually with a ~1-year lag.

CostAPI uses RPP as the authoritative source for US metro-to-metro price comparisons on /v1/prices/us-metros and the /v1/compare endpoint when both endpoints are US. RPP is published for all items, rents, goods, and other services — we default to the all-items index.

Eurostat publishes the Harmonised Index of Consumer Prices (HICP) — the official inflation metric for the EU, EEA, and candidate countries. HICP is released monthly and covers 43 consumption categories (COICOP) at the country level.

CostAPI loads HICP for every available country and period, exposing both all-items and category-specific series. This is the authoritative source for inflation tracking across /v1/cpi/* endpoints for European countries.

The OECD publishes Purchasing Power Parities (PPPs) — currency conversion rates that equalise the purchasing power of different currencies by eliminating the differences in price levels between countries.

CostAPI uses OECD PPPs for real-income conversions on /v1/ppp/* endpoints. When you ask *what does a USD 100k salary in San Francisco really feel like in Berlin?*, the math is salary_usd / PPP_us_to_eur * local_adjustment. PPPs are updated annually.

UBS publishes the triennial *Prices and Earnings* study covering ~77 cities with a standardised basket of 128 goods and services plus wage data for 15 professions. It is the most methodologically rigorous cross-city price benchmark in the industry.

CostAPI uses UBS as the gold-standard cross-city reference for sanity checks on crowd-sourced indices and as the primary source for hours-of-work-to-buy metrics (e.g. *how many hours does a teacher in Zurich work to buy an iPhone?*).

All data is EU-hosted on Hetzner Falkenstein. No PII is logged, GDPR compliant, no warranty — see the footer for the full legal boilerplate.