Every day I generate UUIDs, encode Base64 strings, and convert timestamps. On weekends, I compare mortgage scenarios and plan retirement savings. I got tired of juggling five different websites — none of them doing everything I needed — so I built the toolbox I actually wanted to use every day.
That's SD6 Tools.
What's in the box
14 tools, split across four categories:
Security & Generators
- Password Generator — Cryptographically secure, 8-128 chars, strength indicator
- UUID/GUID Generator — v4 UUIDs with bulk generation and multiple formats
- QR Code Generator — URLs, text, WiFi configs, with customizable output
Finance Calculators
- Mortgage Calculator — Compare up to 4 scenarios side-by-side, full amortization schedules, 5 payment frequencies
- Retirement Calculator — Compound growth projections with inflation, employer matching, visual charts
- Auto Loan Calculator — Tax, insurance, and trade-in breakdown
- Compound Interest Calculator — See the power of compounding over time
- Savings Goal Calculator — Target-based savings planning
- Debt Payoff Calculator — Snowball vs avalanche strategy comparison
- Gas vs Electric Calculator — Total cost of ownership comparison
Developer & Converter Tools
- Text Encoder — Base64, URL, HTML entities, Unicode, hex
- Base Converter — Binary, octal, decimal, hex
- Unit Converter — Hundreds of units across length, weight, temperature, and more
- Timestamp Converter — Unix timestamps ↔ human-readable dates
Why not just use Calculator.net or CyberChef?
Fair question. Here's what's different:
1. Privacy-respecting by default
No cookies until you explicitly opt in. No account creation. All calculations run client-side in your browser — your mortgage numbers never leave your machine. Analytics are consent-based and anonymized.
2. Four languages, not an afterthought
English, French, Spanish, and German — with locale-aware formatting. A German user sees 1.234,56 € while an American sees $1,234.56. This matters when your mortgage calculator shows six-figure numbers.
3. Tools I actually use every day
This isn't a weekend project I abandoned. I use these tools daily — UUID generation while coding, Base64 encoding for API debugging, unit conversions for international projects, and the mortgage calculator when reviewing my own loan options. Every feature exists because I needed it myself.
4. Real scenario comparison
The mortgage calculator lets you compare up to 4 loan scenarios side-by-side. Change the rate, the term, the payment frequency — see the impact instantly. Most free calculators give you one result. This gives you the full picture.
The tech stack
For those curious:
- React 18 + TypeScript 5 — Standard modern stack
- Vite 5 — Fast builds, HMR
- Tailwind CSS — Utility-first styling
- Recharts — Financial charts and visualizations
- react-i18next — Internationalization with <50ms language switching
- Pre-rendered static HTML — Every page is pre-rendered for SEO. No empty SPA shells.
- Cloudflare Pages — Free hosting, global CDN
What I learned building this
Multilingual SEO is hard. Getting hreflang tags, canonical URLs, and pre-rendered content right for 4 languages × 14 tools × blog articles = 276 URLs was a significant challenge. Google doesn't make it easy.
Financial precision matters. JavaScript floating-point arithmetic will betray you. 0.1 + 0.2 !== 0.3 becomes a real problem when calculating 300 monthly mortgage payments. Every calculation is validated against known financial formulas.
Dark mode is expected. It was one of the first feature requests. Every tool supports it.
What's next
More tools are in active development — hash generators, JSON formatters, regex testers, and more. The codebase supports adding new tools quickly thanks to a shared component architecture.
If you have suggestions for tools you'd find useful, I'd love to hear them.
Try it: sd6tools.net
Blog: sd6tools.net/blog
All tools are free. No signup required. Just tools.
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