Open source implementations available on GitHub:

Python - https://github.com/blockstack/secret-sharing

PHP - https://github.com/mathieuk/secretsharer

Node - https://github.com/amper5and/secrets.js

Go - https://github.com/codahale/sss

C - https://github.com/fletcher/c-sss

Ruby - https://github.com/lian/shamir-secret-sharing

Java - https://github.com/timtiemens/secretshare

Rust - https://github.com/sellibitze/secretshare