I have developed an algorithm which can be further customized by including or excluding some of its components. In this way, it provides a basic building block upon which further algorithms can be built, as per requirements. What should be the alternative word which provide the meaning of "basic building block" or like this.
Fundamental is described as:
1a : serving as a basis supporting existence or determining essential structure or function : BASIC
Elemental is another really good word, and is described by MW as:
b(1) : of, relating to, or being the basic or essential constituent of something : FUNDAMENTAL
Both are perfect in describing something rudimentary (which is another good word). You can use fundamental either as a noun, or as an adjective.