58 self-contained browser tools. No signup, no tracking, no backend. Built in one night.
🌐 Live at tools.parallelromb.dev
I run a self-hosted AI system at home called Lumen. On the night of April 29, 2026, I built 58 small browser tools to fill in the gaps in my daily workflow. JSON formatters, cron builders, kanban boards, habit trackers, the works.
Each tool is a single self-contained HTML file. No frameworks, no build step, no telemetry. Open one, use it, close the tab. Your data lives in your browser's localStorage.
I'm publishing them under MIT so anyone can fork, embed, or self-host. They're not novel — there's a JSON formatter on every dev's bookmarks bar — but they're the ones I built, polished enough to use every day, and packaged together so you don't need 58 different tabs.
Because they were built for Lumen, my self-hosted AI system. Some defaults reference my other products (Smara, MCP Doctor, Scoper) — they're examples, fully editable.
It's static HTML. Pick your favorite:
# Python
python3 -m http.server 8000
# Node
npx serve .
# Or just open index.html in your browser
open index.htmlIt's static HTML. Drop the folder anywhere:
- Cloudflare Pages (one-click) — connect this repo, leave build command empty, output dir
/ - GitHub Pages — Settings → Pages → Deploy from branch
main, root/ - Vercel / Netlify — same, no build config needed
- Your own server —
cp -r * /var/www/html/
| Tool | What it does |
|---|---|
| JSON Formatter | Syntax highlighting, tree view, diff compare, YAML/CSV/TS export |
| Regex Tester | 24 patterns, explanation engine, replace/split modes |
| REST API Tester | Mini Postman with collections, env vars, cURL export |
| Text Diff | LCS diff, inline/side-by-side/unified, merge tool |
| Encoder/Decoder | Base64, URL, HTML, JWT, Hash, Unicode, Hex, Binary |
| Cron Builder | Visual builder, 22 presets, export crontab/launchd/systemd/GitHub Actions |
| chmod Calculator | Visual grid, numeric/symbolic, setuid/setgid/sticky |
| IP Network Tools | My IP, lookup, subnet calc, IPv4/6, DNS over HTTPS |
| Epoch Converter | Live clock, 26 timezones, duration calc, date math |
| Unit Converter | CSS/color/time/data/temp/angle, spacing scale, box model |
| Color Palette | 6 harmony modes, WCAG contrast, gradient generator |
| Markdown Editor | Split pane, vanilla parser, multi-doc tabs, find/replace |
| Password Generator | Crypto-secure, passphrase, strength checker, bulk generate |
| Lorem Ipsum | 5 themes, placeholder images, fake data generator |
Kanban Board · Budget Planner · Meal Planner · Presentation Timer · Browser Start Page · Git Activity Heatmap · Pomodoro · Daily Standup · Daily Planner · Meeting Notes · Invoice Generator · Content Calendar · Sprint Retro
Competitor Tracker · A/B Headline Tester · OKR Tracker · Decision Log · Ideas Board · Goals Tracker
Affirmations · Sleep Tracker · Energy Tracker · Fitness Tracker · Gratitude Journal · Personal Journal · Habits
Wealth Dashboard · Cost Dashboard · Expense Tracker
Reading List · Skill Matrix · Interview Prep · Learning Tracker · Bookmarks Manager
Morning Dashboard · API Usage Tracker · Project Health · System Health · Timezone Converter · Network CRM · Quick Notes · Secrets Reference · Weekly Review
All tools run entirely in your browser. No data is sent anywhere — there's no backend to send it to. Your kanban cards, budget figures, journal entries, and everything else live in your browser's localStorage for that origin.
If you clear your browser data, your data is gone. There is no cloud sync. That's a feature.
PRs and issues welcome. Some directions worth taking:
- Bug fixes — anything that's broken
- Polish on existing tools — better mobile, accessibility, edge cases
- New tools that fit the constraint: single HTML file, no backend, no signup
- Themes — currently Apple-style frosted glass; dark theme would be welcome
- Translations — UI strings to other languages
Big rewrites or framework migrations: please open an issue first to discuss.
MIT — do whatever you want, just keep the copyright notice if you redistribute.
Built by Sri (parallelromb.dev) — solo hacker building Lumen, Smara, MCP Doctor, Scoper, and a few other things.
Built with help from Claude (Anthropic) — pair programming, late-night marathon edition.