About FastTool
Free, private astronomy and science calculators — built by an amateur astronomer for the community.
FastTool started as a personal project by an amateur astronomer who was tired of ad-heavy, subscription-walled calculation tools. The goal was simple: build a set of science calculators that run entirely in your browser, never collect user data, and work offline — so you can plan your observation nights from anywhere, even a remote dark-sky site with no cell signal.
Background
The creator of FastTool is a software engineer and avid amateur astronomer with over a decade of experience in web development and astrophotography. With a background in building privacy-first browser applications and a passion for making astronomy accessible, the goal is to combine technical expertise with astronomical knowledge to create tools that are both scientifically accurate and delightful to use.
Technical Expertise
Specializing in Next.js static site generation (SSG), pnpm monorepo architecture, and edge computing. The entire FastTool platform is statically exported — every page is pre-rendered at build time, ensuring instant load times and zero server dependencies. All astronomical calculations use peer-reviewed algorithms (Meeus, USNO, JPL DE440) implemented as pure client-side functions.
Our Tools
FastTool offers a growing suite of free, browser-based science calculators:
- Solar Insight Pro — golden hour, sunrise/sunset, UV index, and daylight planning
- Twilight Calculator — civil, nautical, and astronomical twilight times
- MoonSync — moon phase calendar, lunar illumination, and photography windows
- Sidereal Time Calculator — local and Greenwich sidereal time for telescope alignment
- Telescope FOV Calculator — eyepiece field of view, magnification, and CCD coverage
- Coord Converter — WGS84, GCJ02, BD09 coordinate system conversion
- Planetary Hour Calculator — classical Chaldean planetary hours
- Molar Mass Calculator — molecular weight from any chemical formula
- Eco-Metrics — cloud carbon footprint and remote work CO2 estimator
- FITS Viewer — open astronomical FITS images directly in your browser
Privacy Commitment
Every tool on FastTool runs 100% in your browser. No data — not coordinates, not formulas, not billing amounts — ever leaves your device. We don't use cookies for tracking, we don't have user accounts, and we don't collect analytics that could identify individual users. The only analytics we use (Plausible) are privacy-first, cookie-free, and GDPR-compliant out of the box.
Contact
For questions, suggestions, or collaboration inquiries, find us on GitHub at github.com/fastool-io. We welcome contributions from the astronomy and open-source communities.