Contact

We'd love to hear from you—questions, impressions, bug reports, and anything else.

How to Reach Us

• Via our main site: Please use the contact form on NinjaTech.
• Social media: DM the operator's account on Bluesky or Mastodon (see the links posted on our main site).

Frequently Asked Questions

Q. Are the numbers I enter sent anywhere?

A. This is a question we get often, so let us answer it carefully. The figures you enter into the simulator stay entirely within your browser. Nothing is ever sent to a server. For details, take a look at our Privacy Policy.

Q. Are the calculation formulas correct?

A. On the Calculation Assumptions page, we publish all of the formulas along with their sources. That said, results can vary widely depending on tax systems, market conditions, and individual circumstances, so please treat the displayed values as a rough guide.

Q. Why is this provided for free?

A. We built this tool so that more people can have the chance to think about their own numbers, without the sales bias of financial products getting in the way. We run general advertising to cover the cost of keeping the site going, but we exclude the finance category from ad delivery. For details, take a look at About This Site.

Q. Can I request new features?

A. Please do! As a result of incorporating the feedback we've received, features such as sharing scenarios via URL, automatic addition of childcare costs, a part-time work ON/OFF toggle, and an F.Age (Financial Independence Age) target-amount display are already implemented in v1.2. Next, we'd like to work on scenario comparison, tax deductions for NISA and iDeCo, a dual-income household model, mortgage tax credits, a Portuguese version, and more (for details, see About This Site). If there's a feature you're curious about, we'd be glad to hear from you.