Flask

Express is a minimal and flexible node.js web application framework, providing a robust set of features for building single and multi-page, and hybrid web applications.

It is a powerful and flexible toolkit that makes it easy to build Web APIs.

It is a modern, fast (high-performance), web framework for building APIs with Python 3.6+ based on standard Python type hints.

Sinatra is a DSL for quickly creating web applications in Ruby with minimal effort.

Koa aims to be a smaller, more expressive, and more robust foundation for web applications and APIs. Through leveraging generators Koa allows you to ditch callbacks and greatly increase error-handling. Koa does not bundle any middleware.

Guzzle is a PHP HTTP client that makes it easy to send HTTP requests and trivial to integrate with web services.

It supports both Active Record and Data Mapper patterns, unlike all other JavaScript ORMs currently in existence, which means you can write high quality, loosely coupled, scalable, maintainable applications the most productive way.

Fastify is a web framework highly focused on speed and low overhead. It is inspired from Hapi and Express and as far as we know, it is one of the fastest web frameworks in town. Use Fastify can increase your throughput up to 100%.

It is a simple, yet powerful entity framework for Go, that makes it easy to build and maintain applications with large data-models.

hapi is a simple to use configuration-centric framework with built-in support for input validation, caching, authentication, and other essential facilities for building web applications and services.

Laravel Lumen is a stunningly fast PHP micro-framework for building web applications with expressive, elegant syntax. We believe development must be an enjoyable, creative experience to be truly fulfilling. Lumen attempts to take the pain out of development by easing common tasks used in the majority of web projects, such as routing, database abstraction, queueing, and caching.

It is a high performance, extensible, minimalist web framework for Go (Golang).

Sails is designed to mimic the MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with scalable, service-oriented architecture.

A highly-extensible, open-source Node.js framework that enables you to create dynamic end-to-end REST APIs with little or no coding. Connect to multiple data sources, write business logic in Node.js, glue on top of your existing services and data, connect using JS, iOS & Android SDKs.

Slim is easy to use for both beginners and professionals. Slim favors cleanliness over terseness and common cases over edge cases. Its interface is simple, intuitive, and extensively documented — both online and in the code itself.

It is open source, production quality, framework for developing RESTful Web Services in Java that provides support for JAX-RS APIs and serves as a JAX-RS (JSR 311 & JSR 339) Reference Implementation. It provides it’s own API that extend the JAX-RS toolkit with additional features and utilities to further simplify RESTful service and client development.

It is a framework for building asynchronous servers and clients in connected systems using the Kotlin programming language.

Feathers is a real-time, micro-service web framework for NodeJS that gives you control over your data via RESTful resources, sockets and flexible plug-ins.

This module provides infrastructure for writing single-threaded concurrent code using coroutines, multiplexing I/O access over sockets and other resources, running network clients and servers, and other related primitives.

It is an Async http client/server framework. It supports both client and server Web-Sockets out-of-the-box and avoids Callback. It provides Web-server with middlewares and pluggable routing.

Grape is a REST-like API micro-framework for Ruby. It's designed to run on Rack or complement existing web application frameworks such as Rails and Sinatra by providing a simple DSL to easily develop RESTful APIs. It has built-in support for common conventions, including multiple formats, subdomain/prefix restriction, content negotiation, versioning and much more.

Iron is a high level web framework built in and for Rust, built on hyper. Iron is designed to take advantage of Rust's greatest features - its excellent type system and its principled approach to ownership in both single threaded and multi threaded contexts.

Rails::API is a subset of a normal Rails application, created for applications that don't require all functionality that a complete Rails application provides. It is a bit more lightweight, and consequently a bit faster than a normal Rails application. The main example for its usage is in API applications only, where you usually don't need the entire Rails middleware stack nor template generation.

A Node.js web service framework optimized for building semantically correct RESTful web services ready for production use at scale. it optimizes for introspection and performance.

Falcon is a minimalist WSGI library for building speedy web APIs and app backends. We like to think of Falcon as the Dieter Rams of web frameworks.

It is distributed as a single file module and has no dependencies other than the Python Standard Library. It has fast and pythonic built-in template engine and support for mako, jinja2 and cheetah templates.

It is an Express inspired web framework built on top of Fasthttp, the fastest HTTP engine for Go. Designed to ease things up for fast development with zero memory allocation and performance in mind.

It is a fault tolerant framework. It has built-in load balancer, circuit breaker, retries, timeout and bulkhead features. It is open source and free of charge project.

The Akka HTTP modules implement a full server- and client-side HTTP stack on top of akka-actor and akka-stream. It’s not a web-framework but rather a more general toolkit for providing and consuming HTTP-based services. While interaction with a browser is of course also in scope it is not the primary focus of Akka HTTP.

Nancy is a lightweight, low-ceremony, framework for building HTTP based services on .NET Framework/Core and Mono. The goal of the framework is to stay out of the way as much as possible and provide a super-duper-happy-path to all interactions.

It is a lightweight ASGI framework/toolkit, which is ideal for building high performance asyncio services.

Sapper focuses on easy of use. It is alpha now and only compiled with rust nightly.

It is a simple and expressive Java/Kotlin web framework DSL built for rapid development. Its intention is to provide an alternative for Kotlin/Java developers that want to develop their web applications as expressive as possible and with minimal boilerplate.

Tastypie is a webservice API framework for Django. It provides a convenient, yet powerful and highly customizable abstraction for creating REST-style interfaces.

It is built on the shoulders of Symfony and Pimple and also inspired by sinatra. It has an extension system based around the Pimple micro service-container that makes it even easier to tie in third party libraries.

Javalin started as a fork of the Spark framework but quickly turned into a ground-up rewrite influenced by express.js. Both of these web frameworks are inspired by the modern micro web framework grandfather: Sinatra, so if you’re coming from Ruby then Javalin shouldn’t feel too unfamiliar.

It is a Framework for Node.js platfrom written in pure JavaScript similar to PHP's Laravel or Python's Django or ASP.NET MVC

It is a multi-transport #nodejs API Server with integrated cluster capabilities and delayed tasks.

Python microservices framework that leverages AMQP for RPC. It supports asynchronous and synchronous events.

Aqueduct is an open source, server-side web framework written in Google’s Dart language. Aqueduct promises faster development, experimentation and testing – without sacrificing power.

Lightning Fast, Super Simple micro web framework written in Crystal programming language. Inspired by Sinatra.

It is an American company working with Node.js to create and support StrongLoop Suite, a Mobile API Tier. StrongLoop employs two members of the Node.js Technical Steering Committee. IBM & StrongLoop contribute to and support Open-Source options for the API developer community, such as LoopBack, API Microgateway, and Open API Spec.

Trails is a modern, community-driven web application framework for node.js. It builds on the pedigree of Rails and Grails to accelerate development by adhering to a straightforward, convention-based, API-driven design philosophy.

Hug aims to make developing Python driven APIs as simple as possible, but no simpler. As a result, it drastically simplifies Python API development.

It is a framework for RESTful web-applications based on an extensible content tree. It maps HTTP request URLs to content resources based on the request's path, extension and selectors. Using convention over configuration, requests are processed by scripts and servlets, dynamically selected based on the current resource. This fosters meaningful URLs and resource driven request processing, while the modular nature of Sling allows for specialized server instances that include only what is needed.

It is an open-source Object-Relational Mapping (ORM) for SQL-Databases in PHP 5.5. It allows you to access your database using a set of objects, providing a simple API for storing and retrieving data.

Colossus is a lightweight framework for building high-performance applications in Scala that require non-blocking network I/O. In particular Colossus is focused on low-latency stateless microservices where often the service is little more than an abstraction over a database and/or cache. For this use case, Colossus aims to maximize performance while keeping the interface clean and concise.

A web application microframework for Rust

It is a fast, minimalistic backend framework for Dart. It helps developers effectively build backends in Dart. Currently, it is focused on optimizing the process of building backends that aggregate, compose, and normalize data from multiple sources.

It is a fast, async-ready, OpenAPI, type hints based framework for building APIs. It is based on the open standards for APIs: OpenAPI (previously known as Swagger) and JSON Schema.