Last updated
I'm a software engineer based in Tallinn, Estonia, and I build and maintain FlexUtil in my spare time. The site started as a private collection of calculators and debugging utilities I kept reaching for, and grew into a public project once the same tools started being useful to friends, colleagues, and the occasional stranger who found them via search.
Why me, for this site
FlexUtil sits at the intersection of three areas I have real working experience with:
- Software engineering and developer tooling. My day job is in the testing and quality engineering industry, building systems that handle a lot of moving data. That's where the JSON formatter, the UUID generator (with v7 support), the Base64 encoder, the regex tester, and the password generator come from — tools I personally use regularly while debugging.
- Estonian personal finance and taxation. I live and pay taxes in Estonia, which means I actually deal with the salary calculation, the 22% income tax, the II pillar pension, the VAT reverse charge, and as of 2025 the new motor-vehicle tax. Every Estonian-specific calculator on the site is something I also run for myself.
- Personal-finance literacy. The mortgage, loan, compound interest, and buyout-vs-investing calculators are tools I built to make my own household decisions. The formulas are standard, but the hard part is presenting the trade-offs clearly — which is what the accompanying explanations try to do.
What I'm not
Equally important to what I am: I'm not a certified financial advisor, a tax consultant, an accountant, a lawyer, or a medical professional. The calculators on this site are carefully constructed from primary sources, but they are not a substitute for professional advice on your specific situation. When the stakes are real — a mortgage you'll live with for 25 years, a tax filing the authority will review, a medical decision — consult someone qualified.
How I write and update content
Every tool page and guide has a visible "Last updated" date because stale information is actively harmful in this space — tax rules change, VAT rates are raised, pension schemes are reformed, API specifications evolve. I revisit every tool at least once a year, and sooner whenever something changes in a way that affects the output.
Sources I rely on heavily:
- Estonian Tax and Customs Board (EMTA) — official rates, examples, and commentary for all Estonian tax calculators.
- Riigi Teataja (State Gazette) — the actual text of laws, especially the Liiklusseadus sections governing the new vehicle tax.
- Standard financial formulas — cross-checked against spreadsheets and the calculators published by Estonian retail banks.
- RFCs and ECMAScript specifications — for every developer tool.
If you spot a mistake, an outdated number, or content that no longer matches current rules, please write in — see the contact page. Corrections ship fast.
Editorial independence
The site is funded by Google AdSense. I do not take affiliate commissions, sponsored posts, bank referral fees, or editorial payments from anyone whose product a user might choose based on something they read here. There is no advertising in the tool pages themselves beyond the standard AdSense display slots, and the content above the fold is always editorial, not commercial.
Elsewhere on the internet
Code: github.com/cergfix — where the source for FlexUtil and a handful of other side projects lives.
Get in touch
The best channel is email via the contact page. I read every message and usually reply within a few business days. Good things to send me:
- Corrections — especially if you're an Estonian accountant noticing that a rate or rule is out of date.
- Tool suggestions with a concrete use case. The bar for adding something new is "would I, or would someone I know, actually use this weekly?"
- Bug reports with a screenshot and the browser you're using.