permittivity of vacuum

https://doi.org/10.1351/goldbook.P04508
Fundamental physical constant $$\varepsilon_{0}=\frac{1}{\mu _{0}\ c_{0}^{2}}$$ exactly, where $$\mu_{0}$$ is the permeability of vacuum and $$c_{0}$$ the speed of light in vacuum. It is equal to $$8.854\ 187\ 817\,...\times\ 10^{-12}\ \text{F m}^{-1}$$.
Sources:
CODATA 2006 (https://doi.org/10.1103/RevModPhys.80.633)
Green Book,2nd ed., p. 14 (https://www.cintegrado.com.br/site/documentos/green_book_2ed.pdf)