Nestward is a small collection of financial planning tools, a retirement calculator, a buy-vs-rent comparison, a car lease-vs-buy calculator, an investment growth projector, a portfolio risk estimator, an emergency fund planner, and a debt payoff calculator. It grew out of a single retirement calculator that people kept asking us to extend to cover the rest of their money questions.
This is not financial advice. It's a set of planning tools meant to help you reason about tradeoffs with your own numbers, using math you can inspect. Every calculator shows its assumptions plainly and lets you change them.
Free and private, by construction
Every calculation in Nestward runs entirely in your browser. There's no backend collecting your income, your mortgage balance, or your investment portfolio. Nothing you type into any tool is transmitted to a server or stored in a database. There isn't one. Close the tab and the numbers are gone, unless you've saved a link.
That's a deliberate constraint, not a missing feature. Personal finance numbers are personal. The tools should work the same way a calculator on your desk works: you put numbers in, you get numbers out, and nobody else sees either.
Shareable without an account
Because there's no server and no database, "saving" a scenario works differently than you might expect. Every tool encodes its inputs into a compressed URL parameter, so when you're happy with a scenario, you can share the link directly, with a partner, a friend, or just your future self, and it will reload exactly as you left it. No sign-up, no login, no account to lose access to.
What's here
- Retirement: project your nest egg and estimate a sustainable withdrawal rate.
- Buy vs Rent: compare the real cost of owning versus renting, opportunity cost included.
- Buy vs Lease: compare buying a car outright against leasing it.
- Investment Growth: project how contributions and returns compound over time.
- Portfolio Risk: get a feel for the volatility behind an asset allocation.
- Emergency Fund: size a cash cushion against your actual monthly expenses.
- Debt Payoff: compare payoff strategies across multiple debts.
We'll be using this blog to explain the reasoning behind each tool, the rules of thumb, the math, and the tradeoffs they don't tell you about in the one-paragraph version. Start with The 4% Rule, Explained if you want to understand where the retirement calculator's numbers come from.