About 3sec
Our Philosophy
"Done in 3 seconds." That's our promise.
Open the page → use the tool → finish the task — all in seconds. No sign-up, no install, no learning curve, no uploads.
What We Offer
100+ free online tools covering everyday work and life tasks:
- PDF / image tools: merge, split, compress, page numbers, watermark, sign, EXIF remover, redact
- Text and content tools: QR code, word counter, Markdown, social character limits, prompt tools
- Developer and GEO tools: JSON, Regex, JWT, Hash, Schema, llms.txt, AI crawler checks
- Everyday calculators: age, pet age, TDEE, BMI, timezone, bill splitter, countdown and more
Why Choose 3sec
1. Runs Entirely in Your Browser
Your input never leaves your device. The tools work offline once loaded.
2. 100% Free
No payment. No subscription. No account required.
3. Multi-language
Traditional Chinese, Simplified Chinese, English — with culture-aware tool filtering. ROC date conversion appears only for Taiwan users, not in English.
4. SEO + GEO Friendly
Every tool page uses Schema.org structured data (FAQPage, WebApplication, BreadcrumbList). AI assistants (ChatGPT, Claude, Perplexity, Gemini) can directly read and cite our tools.
Technology
- Built with Astro (static site, zero backend cost)
- Pure HTML/CSS/JavaScript — no heavy framework
- Lightning-fast loading (first paint < 1s)
- Dark Mode (auto-detects system preference)
- HTTPS + Let's Encrypt SSL
- Complete hreflang multi-language tags
Origin Story
3sec was founded in 2026. After years of using cluttered online tools sites, our founder noticed common problems: tools buried in ads, sign-up walls, file uploads (privacy risks), ugly or confusing interfaces.
We decided to build a simple, fast, privacy-respecting tools site.
Roadmap
- Continue adding utility tools
- Improve existing tools (HEIC image support, more languages)
- Build educational articles for complex tools (e.g., understanding APR)