About oToolRun
Small, focused tools. No signup. No uploads. Just results.
The Idea
Most "free online tool" sites bury simple utilities under signup walls, ad popups, and sluggish pages. oToolRun is the opposite: a flat, fast, single-page-per-tool collection of things you'd otherwise reach for a spreadsheet or a stack of browser tabs to do.
Every tool answers one question, runs in one click, and finishes in milliseconds. No accounts. No upload limits. No watermarks.
Why Client-Side?
Every utility on oToolRun runs entirely in your browser using JavaScript and Web APIs. There is no backend that processes your input. This matters because:
- Privacy — text, numbers, and images you enter never travel over the network.
- Speed — no round-trip to a server, so results appear instantly.
- Reliability — works offline once the page is cached, with no API rate limits.
For example, the Image Compressor re-encodes images using the HTML5 Canvas API right inside your browser tab. You can verify in your browser's Network tab that no upload happens.
What's Here
24 tools across writing, finance, health, math, developer utilities, and more:
Writing & Text
- Word Counter & Character Counter
- Case Converter — camelCase, snake_case, title case, and more
- Lorem Ipsum Generator
- Text Diff — side-by-side comparison
- Slugify — URL-safe slug from any text
Finance & Math
- Salary, Mortgage, Loan calculators with full amortization
- Compound Interest Calculator
- Tip Calculator
- Percentage Calculator
- Unit Converter — length, weight, temperature, and more
Health
Date & Time
Developer Tools
- JSON Formatter — pretty-print and validate
- Base64 Converter
- Hash Generator — MD5, SHA-1, SHA-256, SHA-512
- UUID Generator
Security
- Password Generator — cryptographically secure
Images
- Image Compressor — JPG, PNG, WebP
- Image Resizer
Technology
Built with Astro 5 (static output), React 18 for interactive islands, Tailwind CSS v4 for styling, and deployed to Cloudflare Pages. Source code follows TypeScript strict mode. Pages are rendered ahead of time and served from CDN edge nodes — typical first-paint is under 500ms anywhere in the world.
Always Growing
New tools are added regularly. If you need something that isn't here yet, reach out via the Contact page.
How It Stays Free
Hosting is paid through display advertising via Google AdSense. Ads are clearly marked and do not influence tool functionality or output. See our Privacy Policy for what data is collected.