When comparing Meteor vs Koa, the Slant community recommends Meteor for most people. In the question“What are the best node.js web frameworks?” Meteor is ranked 2nd while Koa is ranked 4th. The most important reason people chose Meteor is:
Ranked in these QuestionsQuestion Ranking
Pro Easy to learn
Furthermore, Meteor does not have complex and esoteric concepts that may be hard to grasp by a beginner, it has a clear documentation and well-established coding conventions.
There's also a very useful resource for learning Meteor in the form of a book: Discover Meteor, by the authors of many Meteor packages.
Pro Isomorphic package system
A Meteor package can supply code for both the client and the server, and for mobile (Cordova) apps. For example, an autocomplete package supplies both server code to search a collection, and client code to display the results. The mdg:camera package supports the native camera if the app is built for mobile, or the HTML getUserMedia API to take pictures from the browser.
Pro Auto reload/refresh (hot code push)
Every time a change in the source file is saved, all connected clients will refresh automatically - browser tabs, mobile apps running in the simulator or on the physical device.
Or, deploy a Meteor app (
meteor deploy myapp) and all clients, plus all mobile apps with the server set to
myapp.meteor.com will automatically reload to use the code changes.
This drastically reduces the development cycle for apps in the App Store, where a regular update can wait for one to two weeks before being approved.
Pro Integrated front-end library
Meteor uses both your existing front-end library and it's own library called Blaze, which is integrated beautifully in the framework and fulfills the purpose of a true MV* front-end framework.
Pro Full-stack reactivity
Changes in the database will be propagated to all subscribed clients in real time, without you having to write any code.
Meteor is the 10th most starred project on GitHub and has overtaken even Rails.
Pro Seamless communication between client and server
Meteor is built on top of Node.js and jQuery on the client.
Meteor enables the client and server to communicate data seamlessly, in real-time. You don't have to write any REST API or pub/sub code - Meteor takes care of it all automatically for you.
Pro Support for MySQL, PostgreSQL and Redis
While Meteor only supports MongoDB and Redis natively, MySQL support is on the roadmap, and there are 3rd-party packages that integrate MySQL reactively with Meteor to some extent, such as numtel:mysql. For reactive PostgreSQL support, there is numtel:pg.
Pro Real-time testing framework
Meteor also has an official testing framework called Velocity. Velocity enables real-time unit testing and integration with Jasmine or Mocha syntax. Tests are automatically run when code is saved and the testing result is indicated by a green or red dot in the upper right corner of the app.
Pro Includes latency compensation
The client will mimic instant server-side response, and updates automatically if it was different once the information is available.
Pro Built-in security
Meteor takes care of many concerns with it's out-of-the-box security measures.
Pro Mobile apps from the same code base
Moreover, these hybrid mobile apps benefit from hot code push, which dramatically accelerates the development cycle.
Pro Eliminates the need to look for a database to use
Meteor uses MongoDB, eliminating the choice among NoSQL databases. MongoDB is highly scalable - used to store petabytes of data and perform billions of operations daily at eBay, FIFA, Adobe, Craigslist, McAffee, Foursquare and others.
Pro Gets rid of Node's callbacks
Although Meteor's server side runs on top of Node.js, it manages to avoid callbacks by making use of Fibers.
Pro Extensive ecosystem
Meteor's package repository called Atmosphere has more than 5000 packages available. What's more is that Meteor can also use into the packages available for the Node ecosystem.
Pro Powerful performance monitoring tools
Meteor uses Kadira which is an excellent performance monitoring tool for Meteor apps. It profiles CPU and RAM consumption, subscription latency and throughput etc.
Pro VC-funded open-source
Bright future for Meteor - funded by venture capital and open-source.
Pro In-app debugging
The community behind Meteor has created a useful application for debugging Meteor apps that will automatically delete collections and display client-side documents, allow you to control subscriptions and lets you modify the documents.
Meteor also has great support for server-side debugging, and WebStorm has also released full support for Meteor, including debugging capabilities.
Pro Generator support from ground up
Using generators (a bleeding edge feature, even for Node.js) would clean up your code from the mess caused by all those callbacks; making your code more manageable.
Pro Development team has a proven track record
Koa is developed by the team behind a widely used node.js framework (express.js).
Pro Extremely lightweight
Koa is very lightweight with just 550 lines of code.
Pro async/await keywords are supported and has transcended beyond generator functions
Generators functions are of course a huge plus, but at the time Koa team has transcended generations functions and shifted towards async/await style programming. It has made the Koa best framework available in the market.
Pro Built for ES6
Con No native SEO support (no server-side rendering)
Meteor does not have support for server-side rendering of views, which is extremely helpful when it comes to SEO. However, there's a third-party server-side rendering package available for download. The Meteor team has also said that server-side rendering is on the roadmap.
Con Officially supports only MongoDB, which is well-known to have issues with data integrity
MongoDB advertises scalability but only if you don't care about data-integrity. There are other backend options but none of them are officially supported.
Con Requires reliable network connection
It's common for the front-end and back-end to lose sync if an internet connection is flaky. Even though the connection should be in real-time, if the connection is weak, you may lose that real-time sync. For example, in chat applications you may have to refresh the page to get the latest updated data from the server.
Con Not compatible with express style middleware
Koa uses generators which are not compatible with any other type of Node.js framework middleware.