Survey Sampling Online Tools

Sample size calculator - One sample
Sample size calculator for estimating a proportion or for detecting a change to a known proportion.

Sample size calculator - Two samples
Sample size calculator for detecting a change between two proportions with survey data from two independent surveys.

Sampling.Kit (Shiny application):
The Sampling.Kit is a web-tool designed for survey designers and samplers to perform several functions, such as sample calculation, sample allocation, precision estimation and significance testing.