About SlimUtils
SlimUtils is a free collection of 51 everyday web tools — calculators, generators, and converters that run entirely in your browser. No account, no subscription, no data uploaded anywhere. Just open the tool and use it.
We built SlimUtils because most online tools are cluttered with ads before you even see the tool, require you to create an account for no reason, or upload your data to a server just to count words or generate a password. We wanted something cleaner: fast, focused tools that respect your privacy and get out of your way.
What We Offer
SlimUtils currently includes 51 free tools across 11 categories:
- Finance — Tip calculator with bill splitting, loan & mortgage calculator with amortization, VAT calculator (26 countries), FIRE / financial independence calculator, percentage calculator
- Developer — JSON formatter, Base64 encoder/decoder, URL encoder/decoder, HTML encoder/decoder, hash generator (MD5, SHA-1, SHA-256…), JWT decoder, SQL formatter, JavaScript minifier/formatter, UUID generator, color converter, cron expression generator, CSV to Markdown table, SVG Data URI encoder, chmod calculator, keycode info, meta tag builder, aspect ratio calculator, color accessibility checker
- Productivity — QR code generator, business days calculator, date duration calculator, countdown timer, meeting cost calculator, timezone overlap calculator, Pomodoro timer, BPM tapper
- Design — CSS gradient generator, box shadow generator, glassmorphism generator, golden ratio calculator, CSS triangle generator
- AI — Midjourney prompt builder, AI prompt library, image-to-video maker
- Writing — Word counter with reading time, case converter (camelCase, snake_case, kebab-case…), Lorem ipsum generator
- Security — Cryptographically random password generator, 100% local
- Health — Pregnancy due date calculator with trimester tracking
- Family — Baby name meanings (5,000+ names), sibling name matcher
- Marketing — UTM builder for campaign tracking
- Games — Scrabble word finder (TWL, SOWPODS, WWF dictionaries)
How It Works
Every tool on SlimUtils runs client-side — meaning all processing happens inside your browser using JavaScript. When you generate a password, count words, or create a QR code, nothing is sent to any server. You can verify this by watching the Network tab in your browser's DevTools: you'll see zero requests while using the tools.
Who Is This For?
- Anyone who needs a quick calculation or conversion without installing an app
- Developers who need test data, JSON formatting, JWT decoding, or CSS generators during a project
- Writers and students who need word counts and character limits for assignments or social media
- Parents researching baby names or pregnancy milestones
- Business professionals calculating loan payments, meeting costs, deadlines, or tip splits
- Designers building gradients, shadows, glassmorphism effects, or checking color accessibility
Privacy
We take privacy seriously. No tool on SlimUtils collects, stores, or transmits any input you enter. We use basic analytics (page views only) to understand which tools are most useful. Read our full Privacy Policy for details.
Who Builds SlimUtils
SlimUtils is built and maintained by Andre Semek, a cloud and software engineer based in Germany. You can find more about my professional work at semek.org, where I write about cloud architecture, AI agents, and software engineering. SlimUtils is a side project I started because I kept opening a dozen browser tabs for basic tasks (formatting JSON, calculating tips, generating passwords) and wanted them all in one clean place.
The tools are built with Astro 6, React 18, TypeScript, and Tailwind CSS, then deployed on Cloudflare Pages. The source code follows web standards strictly — every tool runs entirely in your browser, with no server-side processing of your input. New tools are added regularly based on personal need and reader feedback.
If you have a suggestion for a tool that belongs here — something you keep searching for and can never find a clean version of — reach out via the contact page. Most tools on SlimUtils started exactly that way: someone described a frustration, and I built the smallest possible thing that fixed it.
Contact
Questions, feedback, or tool suggestions? We'd love to hear from you. Reach us at [email protected] or use the contact form.