Open K-Anonymized Aggregates from a Free Personal-Finance Calculator Platform: Methodology, Dataset, and Public Mirror

Working paper describing CalcFi's methodology: how every calculator on calcfi.app is derived from US primary economic and tax sources (IRS, BLS, BEA, FRED, U.S. Treasury, CFPB, HUD, U.S. Census Bureau, SSA, Freddie Mac PMMS), how reproducibility is enforced via versioned rate snapshots, and how the data layer is exposed via open REST APIs, an MCP server (distributed on npm, PyPI, and Homebrew), and llms.txt for LLM-discovery. The paper documents schema design, provenance chains, citation policy, AI Insight Engine boundaries, k-anonymity in aggregate insights, and the open-data archival flow into Zenodo. This record is part of the CalcFi open data community on Zenodo — the citation archive for the CalcFi (calcfi.app) open finance calculator and US economic data project. Every CalcFi calculator on the live site links to its primary source, and every rate series is versioned with last-update timestamps and primary-source URLs. This record makes the data citable with a permanent DOI under CC-BY 4.0. Primary data sources cited in CalcFi outputs Internal Revenue Service (IRS) · Bureau of Labor Statistics (BLS) · Bureau of Economic Analysis (BEA) · Federal Reserve Economic Data (FRED) · U.S. Treasury · Consumer Financial Protection Bureau (CFPB) · U.S. Department of Housing and Urban Development (HUD) · U.S. Census Bureau · Social Security Administration (SSA) · Freddie Mac Primary Mortgage Market Survey (PMMS) · U.S. Energy Information Administration (EIA) · Federal Deposit Insurance Corporation (FDIC) · World Bank · CoinGecko · Frankfurter (ECB FX) Related CalcFi surfaces Live site Methodology and provenance Developer documentation and OpenAPI Open data hub Research outputs index Calculator registry (machine readable JSON) Live rate snapshot (machine readable JSON) LLM-discovery file Privacy and AI data practices Kaggle reproducibility notebooks Hugging Face Spaces (live calculator demos) MCP server on npm MCP server on PyPI CalcFi Zenodo community ORCID author profile How to cite CalcFi data @misc{calcfi, author = {Salmisto, Jere}, title = {CalcFi: Open Personal Finance Calculators and Cited US Economic Data}, year = {2026}, publisher = {Zenodo}, url = {https://zenodo.org/communities/calcfi}, note = {Live site: https://calcfi.app} } For this specific record, use the DOI displayed above the citation block on this Zenodo page. License Released under Creative Commons Attribution 4.0 International (CC-BY 4.0). Attribution string: CalcFi (calcfi.app). Disclaimer All content is educational. Not financial, tax, or legal advice. Numbers are computed from user inputs and primary-source data; consult a licensed professional for decisions involving your money. Maintainer CalcFi is maintained by Jere Salmisto (ORCID 0009-0000-0916-8684). Contact: hello@calcfi.app.