Koa vs Sails.js
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
Small Node.js web framework built on async functions for writing HTTP middleware.
Open source · MIT
A Node.js web framework for building MVC-style apps and APIs, with realtime features like chat.
The short answer
Choose Koa if you need…
- Node.js developers who want a minimal web framework they can shape themselves
- Teams building APIs or web servers who prefer async/await middleware
- Developers familiar with Express-style middleware who want a smaller core
Choose Sails.js if you need…
- JavaScript developers who want a Rails-style MVC structure in Node.js
- Teams building realtime features such as chat, as the README highlights
- Developers migrating or extending an existing Express project, since the README says Sails actions are compatible with Connect middleware
- Projects that may need to switch databases, thanks to Waterline's adapter system
Side-by-side
| Koa | Sails.js | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 35.7k | 22.8k |
| Setup difficulty | Intermediate | Intermediate |
| How you get it | Install with a package manager | Install with a package manager |
| Main language | JavaScript | JavaScript |
| Last code update | 4 days ago | 5 months ago |
What each one is
Koa
Koa is a web framework for Node.js that lets developers build HTTP servers and APIs by chaining middleware functions. It uses modern async/await syntax, so each step can pause, wait for work like a database call, and then pass control onward. Developers use it as a lightweight base they can extend with their own choice of add-ons.
Sails.js
Sails.js is a web framework for Node.js that helps you build custom server-side apps and APIs. Its structure resembles the MVC pattern used in frameworks like Ruby on Rails, and the README says it is especially good for realtime features such as chat. It is built on Express and Socket.io and includes Waterline, an ORM that connects to several databases.
Best for
Koa
- Node.js developers who want a minimal web framework they can shape themselves
- Teams building APIs or web servers who prefer async/await middleware
- Developers familiar with Express-style middleware who want a smaller core
Sails.js
- JavaScript developers who want a Rails-style MVC structure in Node.js
- Teams building realtime features such as chat, as the README highlights
- Developers migrating or extending an existing Express project, since the README says Sails actions are compatible with Connect middleware
- Projects that may need to switch databases, thanks to Waterline's adapter system
Strengths
Koa
- Uses ES2017 async functions, so control flow reads top to bottom without callback nesting
- Minimal core keeps the framework small and lets you choose extra pieces
- MIT licensed and widely used, with a large star count on GitHub
Sails.js
- Familiar MVC structure that the README says resembles Ruby on Rails
- Built-in realtime support via Socket.io, with WebSockets usable alongside the API
- Waterline ORM supports several databases through a documented adapter system
Not ideal for
Koa
- Complete beginners new to Node.js, since Koa ships with little built in and assumes familiarity with HTTP and middleware
- Projects that need a full batteries-included framework out of the box, because routing, body parsing and similar features come from separate packages
Sails.js
- People new to JavaScript or Node.js, since it assumes familiarity with the ecosystem
- Developers who want a minimal framework with little built-in structure, as Sails provides a fairly complete MVC layout
- Projects needing a database with no available adapter, since support depends on Waterline adapters
Trade-offs
Koa
- Little is included by default, so routing and parsing require additional packages
- Public README was truncated here, so detailed API and version-specific behavior could not be verified from this entry
Sails.js
- The README mentions upgrade guides between major releases, which implies version changes you will need to follow
- Community adapters vary in maintenance, and the README links many of them to old or search pages
- The README is truncated and does not detail the full feature set or requirements
Getting started
Sails.js
Install Sails globally
npm install sails -gCreate a new app
sails new my-appFrequently asked questions
What is the difference between Koa and Sails.js?
Koa: Small Node.js web framework built on async functions for writing HTTP middleware. Sails.js: A Node.js web framework for building MVC-style apps and APIs, with realtime features like chat. Koa suits node.js developers who want a minimal web framework they can shape themselves, while Sails.js suits javascript developers who want a rails-style mvc structure in node.js.
Are Koa and Sails.js free?
Koa: Free and open source. Sails.js: Free and open source.
Is Koa or Sails.js more popular?
Koa has more GitHub stars (35.7k) than Sails.js (22.8k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to Koa and Sails.js?
Other options people compare them with include Express, Fastify, Hono, Apollo Server.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.