#wavelength

Electromagnetic-wave maths as an API, computed locally and deterministically. The convert endpoint converts between wavelength and frequency (λ = c ÷ f) and also reports the period, the wavenumber, the photon energy and the part of the spectrum — optionally for light travelling in a medium of a given refractive index, where the wavelength scales by 1/n while the frequency stays the same. The energy endpoint gives the photon energy in joules, electron-volts and kilo-electron-volts from a wavelength or frequency (E = h·f = h·c ÷ λ). The band endpoint classifies a wavelength or frequency into the electromagnetic spectrum — radio, microwave, infrared, visible, ultraviolet, X-ray or gamma — and adds the ITU radio sub-band (ELF through EHF) and the approximate colour for visible light. Frequencies accept Hz/kHz/MHz/GHz/THz and wavelengths m/cm/mm/µm/nm/pm/ångström. Everything is computed locally and deterministically, so it is instant and private. Ideal for RF and antenna tools, optics and photonics, spectroscopy and lab software, physics and astronomy education, and amateur radio. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is electromagnetic-wave physics; for general unit conversion use a unit-conversion API.

api.oanor.com/wavelength-api

Turn physical light into RGB colours — entirely locally. The kelvin endpoint converts a colour temperature in Kelvin into the RGB colour of a black body at that temperature: warm candle and incandescent tones below 3000 K, neutral and daylight whites around 5000–6500 K, and cool bluish light above, using Tanner Helland's widely-used approximation and returning hex, an rgb() string and a plain-English description (candlelight, warm white, neutral, daylight, cool). The wavelength endpoint converts a wavelength of visible light in nanometres (380–780 nm) into the approximate RGB colour the human eye perceives, with the natural intensity fall-off at the violet and red edges of the spectrum, and names the band (violet, blue, cyan, green, yellow, orange, red). Everything is computed locally and deterministically, so it is instant and private. Ideal for lighting and smart-bulb apps, photography and white-balance tools, data-visualisation of temperature or spectra, theming and UI accents, and science and education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. These are perceptual approximations, not colorimetric CIE conversions; for hex/RGB/HSL conversion and palettes use a colour API.

api.oanor.com/colortemp-api