I've begun compiling a list of resources to answer the question "How do I secure my app?" It works by going to the page, finding your technology stack using Ctrl+F or Cmd+F and then visiting the resources. All resources have the top most common pitfalls and exactly how to cover them with code examples.
So far, I've collected resources on JavaScript, Node.js, Express.js, Angular.js, web dev, PHP, C#/.NET, C++, C, MongoDB, SQL Server, IoT devices, as well as related tech such as Ubuntu Server hardening, NGINX, and JSON Web Tokens (JWTs) amongst others. This is only v0.1 of the resource list and I will continue to update, refine, and organize it. I will probably create a new blog post here every time I make a major update.
Enjoy and feel free to make suggestions. Thank you.