Deno Saur

Deno Saur is a web application framework optimized for rapid development. Its goal is to provide a full set of features for creating monolithic, server-side applications with Deno.



To install Deno Saur, make sure you have Deno installed, then run:

deno install --unstable --allow-net --allow-env --allow-read=. --allow-write --allow-run --name saur

This will install the CLI to ~/.deno/bin/, and give it permissions to read and write to the filesystem, as well as run commands. You can define which directory it has write access to by passing that directory into the command:

deno install --allow-read=. --allow-write=~/Code --allow-run saur

Once everything is installed and compiled, you’ll want to have the saur command in your $PATH if you haven’t done so already:

export PATH=~/.deno/bin:$PATH

You can now create your first application by running:

saur new my-first-app

This command will create a new directory and generate some boilerplate files you’ll need for Saur to work. It will also install the bin/server script for easily starting the application server, which is used by saur server to run your application. This is due to Deno’s security model. The saur CLI has no network access, meaning it can’t make outbound calls to the Internet, however, it has read/write access to your entire filesystem and the ability to run commands. The bin/server script does have network access, but only the ability to write to the filesystem within its own directory, and no ability to run arbitrary commands. This means that even if you download a malicious plugin or module, it won’t be able to change any information outside of your app, so you can isolate and contain its impact. The most it can do is affect your actual application code and make outbound calls to the Internet, which is still bad, but not as bad as losing your identity.


In JavaScript backend development, there aren’t very many resources for a fully-featured web application framework. While smaller libraries can be cobbled together to make an application, there’s nothing that can get you started as quickly as something like Rails. For many developers, running rails new is a lot easier than setting up a project with yarn and including all the dependencies you’ll need to get started. In addition, once you get a sufficient framework of sorts going, you still don’t have any generators or a common way of running tasks that can be exported and modularized. The result is a lot of projects out there are difficult to navigate, which makes developing on them much harder.

Saur attempts to solve these problems by taking a lot of what we’ve learned from Rails, Django, and other “web MVC” frameworks and applying them in the world of server-side JavaScript. By imitating their successes, and addressing some of their faults, we’re ensuring that backend applications can be made quickly, easily, and securely in JavaScript without having to reach for additional tools.

Much like how the beauty of Ruby spurred the pragmatic development of Rails, Saur probably wouldn’t have been as straightforward to use without the accomplishments of the Deno JavaScript runtime. Deno’s built-in TypeScript, code formatting, external module importing (without the need for a centralized package manager!) and Promise-based asynchronous I/O is a major positive boon to the Saur framework, bringing with it the speed and correctness you’ve come to expect from your backend, without the weird hacks and questionable runtimes that plague Node.js applications. No need to set --use-experimental here, ECMAScript modules and top-level async/await are fully supported in Deno, and the runtime itself is written in Rust to ensure maximum compatibility and minimize nasty segfault bugs that are rampant throughout the C-based interpreted languages that most of the Web runs on.