Fastify 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
A fast, low-overhead web framework for building servers and APIs with Node.js.
Open source · MIT
A Node.js web framework for building MVC-style apps and APIs, with realtime features like chat.
The short answer
Choose Fastify if you need…
- Node.js developers building JSON APIs or backend services
- Teams that care about request throughput and want a lightweight framework
- Projects that want schema-based validation of routes and responses
- Developers who want to organize code into reusable plugins
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
| Fastify | Sails.js | |
|---|---|---|
| Type | Library | Library |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 37.3k | 22.8k |
| Setup difficulty | Beginner | 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
Fastify
Fastify is a framework for building web servers and APIs in Node.js. You define routes, such as a URL that returns data, and Fastify handles incoming requests with minimal extra work per request. It also offers a plugin system, input and output validation using JSON Schema, and built-in logging through Pino.
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
Fastify
- Node.js developers building JSON APIs or backend services
- Teams that care about request throughput and want a lightweight framework
- Projects that want schema-based validation of routes and responses
- Developers who want to organize code into reusable plugins
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
Fastify
- The README reports high request throughput in a synthetic hello-world benchmark, with the caveat that real results depend on the application
- Supports JSON Schema validation and serialization for routes
- Includes a plugin architecture and hooks for extending behavior
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
Fastify
- Beginners who have not yet learned Node.js basics, since the framework assumes JavaScript familiarity
- Projects that need a non-Node.js language, because Fastify is for Node.js only
- Teams expecting a large built-in feature set; much functionality comes from plugins, per the docs
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
Fastify
- Benchmark figures come from the maintainers' own synthetic test and may not match your workload
- The README's benchmark table lists an older Fastify version (4.0.0), so the numbers are not current
- Binding to 0.0.0.0 in containers requires care, since the README warns of security risks
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
Fastify
Install Fastify in an existing project
npm i fastifyGenerate a new Fastify project
npm init fastifySails.js
Install Sails globally
npm install sails -gCreate a new app
sails new my-appFrequently asked questions
What is the difference between Fastify and Sails.js?
Fastify: A fast, low-overhead web framework for building servers and APIs with Node.js. Sails.js: A Node.js web framework for building MVC-style apps and APIs, with realtime features like chat. Fastify suits node.js developers building json apis or backend services, while Sails.js suits javascript developers who want a rails-style mvc structure in node.js.
Are Fastify and Sails.js free?
Fastify: Free and open source. Sails.js: Free and open source.
Which is easier to set up, Fastify or Sails.js?
Fastify is easier to get started with (rated beginner); Sails.js is rated intermediate and usually needs more setup.
Is Fastify or Sails.js more popular?
Fastify has more GitHub stars (37.3k) 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 Fastify and Sails.js?
Other options people compare them with include Express, Koa.
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.