ML Frameworks
I looked at various solutions AWS provided in their ML stack(more details at https://aws.amazon.com/amazon-ai/?nc2=h_l3_ai). If you are an AWS shop and doesn't have much of ML/AI in-house expertise etc, it is a great place to start and learn and apply for simple projects.
However I have used following frameworks to build my last project.
Tensor Flow : https://www.tensorflow.org/ - Most popular framework used for large-scale numeric computation. Born out of Google, used by various well-known companies and applications. As the name suggests, frameworks reduces complexity of numeric computation using data flow graphs.
Checkout TensorFlow Cheatsheet, this gives you great idea of
https://github.com/kailashahirwar/cheatsheets-ai/blob/master/PDFs/Tensorflow.pdf?imm_mid=0f769c&cmp=em-data-na-na-newsltr_20171025
Apache Spark ML Library : Very popular Open Source framework, It is a module as part of Spark. Provides out-of box implementations and API for various ML algorithms(Classification, Regression, Clustering, Recommendation to name a few).
https://spark.apache.org/mllib/
You can read following article, which can be helpful knowing the landscape.
https://www.infoworld.com/article/2853707/robotics/11-open-source-tools-machine-learning.html#slide13
CoreNLP : Standford publishes opensource CoreNLP library. Very useful to build basic NLP applications. A sample app could be parsing reviews from a website and take action based on that.
https://stanfordnlp.github.io/CoreNLP/