FinanceFriend24 is a finance education and tools website built by one person, for people who want depth without paying for a Bloomberg terminal.
I built this site because the gap between professional-grade financial analysis and what is freely available online is unnecessarily wide. The calculations that institutional investors run every day are not particularly complex. They are simply buried inside expensive software, academic papers, or incomplete blog posts that get the formulas wrong. Every tool and guide on this site is designed to close that gap.
I am Fil J., a finance professional with over six years of hands-on experience across financial market supervision, corporate finance and portfolio management. My background combines five years of formal finance education with direct working exposure to the markets I write about.
I have evaluated financial instruments from multiple angles in my career: as a supervisor assessing how products behave under stress and how they should be regulated, as a corporate finance practitioner working on transactions and valuation, and as a portfolio manager responsible for investment decisions and risk management. Each perspective taught me something different about how financial instruments actually work versus how they are described in textbooks.
That combination is what shapes how this site is built. The calculators match how professionals model these instruments in practice. The guides explain not just the definitions but the mechanics behind them, the assumptions that go into them, and the situations where standard formulas stop being reliable.
I am based in Central Europe and work fluently in English. Most content on FinanceFriend24 is written in English for an international audience, with a focus on internationally-used instruments and conventions.
Three frustrations from my professional work drove the decision to build this:
First, the gap between what tools cost and what they should cost. Calculating effective duration on a callable bond, modelling a repo transaction with proper settlement and accrued interest mechanics, or computing a Sortino ratio correctly are not operations that should require a five-figure Bloomberg subscription. The math is well-known. What was missing was someone willing to build the tools accessibly.
Second, the gap between professional analysis and what is freely available. Searching online for “effective duration” typically produces either an oversimplified definition or an academic paper. Searching for “Macaulay Duration calculator” typically produces tools that omit the inputs that actually matter (clean price, settlement date, day count convention) in favour of asking for the YTM directly, which defeats the purpose. I wanted to build calculators that match the professional standard, not consumer-grade approximations.
Third, the gap in honest explanation. Most finance content online either oversimplifies (which is misleading) or overcomplicates (which is impenetrable). I write the way I would explain a concept to a colleague: precise, with the mechanics shown, but without unnecessary jargon. The goal is that a finance student, a retail investor, and a working professional can all find value here at different depths.
Professional-grade calculators covering fixed income, mortgage financing, investment performance metrics and personal finance. Each is built to match how the underlying instrument works in practice, not a simplified consumer version. The strongest cluster covers fixed income: Bond Duration, Effective Duration, Repo and Accrued Interest.
In-depth explanations of how financial instruments work, written for professionals and serious learners. The Repo vs Reverse Repo guide, the Internal Rate of Return guide, the Sortino Ratio analysis, and the bond duration articles are examples of the depth.
The same approach applied to mortgages, leases and savings decisions. The Understanding Mortgages guide covers amortisation mathematics, refinancing break-even analysis, and LTV pricing bands at a depth most personal finance sites avoid.
Every calculator and guide on FinanceFriend24 follows the same editorial principles:
Worked examples with specific numbers. Generic explanations mean nothing in finance. Every concept on this site is demonstrated with actual calculations using realistic inputs, so the reader can verify the math and apply it to their own situation.
Honest disclosure of limitations. Every financial metric has assumptions and edge cases where it breaks down. Modified Duration assumes linear price-yield relationships. Sharpe ratio penalises upside volatility. IRR assumes reinvestment at the IRR itself. These limitations are explained, not hidden.
No reliance on AI-generated content. Every article on this site is written or reviewed personally. The depth and specificity that distinguishes this content from generic finance websites comes from years of working with these instruments, not from a language model.
Regular review and updates. Content is reviewed periodically to reflect changes in market conventions (such as the May 2024 transition to T+1 settlement in US securities), policy changes (such as Google’s restrictions on FAQ rich results), and any errors readers identify.
No paywalls. All content is free. No registration is required for any calculator or article. The site is funded through unobtrusive display advertising and never through paid placement or sponsored content.
FinanceFriend24 is an educational resource. Nothing on this site constitutes investment advice, financial advice or a recommendation to buy, sell or hold any security or instrument. The content is intended to help readers understand financial concepts and run their own analysis.
Individual financial decisions should be made in consultation with a qualified financial advisor familiar with your specific circumstances, tax situation, and jurisdiction. The calculators on this site are tools for analysis, not substitutes for professional advice.
I have made every effort to ensure accuracy, but errors are possible. If you find one, I want to know about it. Use the contact information below to reach me directly.
FinanceFriend24 is built for a global audience, but international financial markets have important regional differences. Where conventions vary materially by jurisdiction – day count conventions, tax treatment of bonds, mortgage regulations, currency-specific market practices – I try to flag those differences clearly rather than presenting one market’s conventions as universal.
The strongest content focuses on internationally-used instruments: US Treasuries, corporate bonds, repurchase agreements, standard mortgage structures, and performance metrics applied across global markets.
If you spot an error, want to suggest a new calculator, or need clarification on any content, I read every message:
Email: [email protected]
For professional verification of credentials, I am open to direct communication. Serious enquiries from financial journalists, industry researchers, or potential collaborators can use the same email address.
FinanceFriend24 is a continuously developing project. New calculators and guides are added based on what readers find most useful. The roadmap reflects gaps in the freely-available financial education space that I have personal expertise to fill.
Thank you for visiting.
Fil J., Founder of FinanceFriend24