Assertible

It is the only complete API development environment, used by nearly five million developers and more than 100,000 companies worldwide.

Kibana is an open source (Apache Licensed), browser based analytics and search dashboard for Elasticsearch. Kibana is a snap to setup and start using. Kibana strives to be easy to get started with, while also being flexible and powerful, just like Elasticsearch.

Grafana is a general purpose dashboard and graph composer. It's focused on providing rich ways to visualize time series metrics, mainly though graphs but supports other ways to visualize data through a pluggable panel architecture. It currently has rich support for for Graphite, InfluxDB and OpenTSDB. But supports other data sources via plugins.

Prometheus is a systems and service monitoring system. It collects metrics from configured targets at given intervals, evaluates rule expressions, displays the results, and can trigger alerts if some condition is observed to be true.

Nagios is a host/service/network monitoring program written in C and released under the GNU General Public License.

Insomnia is a powerful REST API Client with cookie management, environment variables, code generation, and authentication for Mac, Window, and Linux.

It is probably the most popular HTTP client library for .NET. Featuring automatic serialization and deserialization, request and response type detection, variety of authentications and other useful features

It is a publicly available application programming interface that provides developers with programmatic access to a proprietary software application or web service.

Zabbix is a mature and effortless enterprise-class open source monitoring solution for network monitoring and application monitoring of millions of metrics.

It is a set of libraries for various languages that allow you to collect application metrics and distributed traces, then transfer the data to a backend of your choice in real time. This data can be analyzed by developers and admins to understand the health of the application and debug problems.

Retrofit turns your HTTP API into a Java interface

Graphite does two things: 1) Store numeric time-series data and 2) Render graphs of this data on demand

It is a network daemon that runs on the Node.js platform and listens for statistics, like counters and timers, sent over UDP or TCP and sends aggregates to one or more pluggable backend services (e.g., Graphite).

Jaeger, a Distributed Tracing System

It is an agent for collecting, processing, aggregating, and writing metrics. Design goals are to have a minimal memory footprint with a plugin system so that developers in the community can easily add support for collecting metrics.

It defines a standard, language-agnostic interface to RESTful APIs which allows both humans and computers to discover and understand the capabilities of the service without access to source code, documentation, or through network traffic inspection.

Consistent, expressive, vendor-neutral APIs for distributed tracing and context propagation.

API management, design, analytics, and security are at the heart of modern digital architecture. The Apigee intelligent API platform is a complete solution for moving business to the digital world.

It is an open source functional Testing tool for API Testing. It supports multiple protocols such as SOAP, REST, HTTP, JMS, AMF and JDBC. It supports functional tests, security tests, and virtualization.

Paw is a full-featured and beautifully designed Mac app that makes interaction with REST services delightful. Either you are an API maker or consumer, Paw helps you build HTTP requests, inspect the server's response and even generate client code.

Netdata collects metrics per second & presents them in low-latency dashboards. It's designed to run on all of your physical & virtual servers, cloud deployments, Kubernetes clusters & edge/IoT devices, to monitor systems, containers & apps

It provides a single set of APIs, libraries, agents, and collector services to capture distributed traces and metrics from your application. You can analyze them using Prometheus, Jaeger, and other observability tools.

Sensu is the future-proof solution for multi-cloud monitoring at scale. The Sensu monitoring event pipeline empowers businesses to automate their monitoring workflows and gain deep visibility into their multi-cloud environments.

It helps gather timing data needed to troubleshoot latency problems in service architectures. Features include both the collection and lookup of this data.

It is a Swift-based HTTP networking library for iOS and macOS. It provides an elegant interface on top of Apple's Foundation networking stack that simplifies a number of common networking tasks.

It is an open source project which allows generation of API client libraries (SDK generation), server stubs, and documentation automatically from an OpenAPI Specification.

It can monitor and manage distributed computer systems, conduct automatic maintenance and repair and execute meaningful causal actions in error situations.

Combines API test-automation, mocks and performance-testing into a single, unified framework. The BDD syntax popularized by Cucumber is language-neutral, and easy for even non-programmers. Besides powerful JSON & XML assertions, you can run tests in parallel for speed - which is critical for HTTP API testing.

RESTful API Modeling Language (RAML) makes it easy to manage the whole API lifecycle from design to sharing. It's concise - you only write what you need to define - and reusable. It is machine readable API design that is actually human friendly.

Charles is a web proxy (HTTP Proxy / HTTP Monitor) that runs on your own computer. Your web browser (or any other Internet application) is then configured to access the Internet through Charles, and Charles is then able to record and display for you all of the data that is sent and received.

Created with <3 for front-end developers who need a quick back-end for prototyping and mocking.

Keep tabs on all aspects of your API's performance with uptime monitoring, integration testing, logging and real-time monitoring.

Newman is a command-line collection runner for Postman. It allows you to effortlessly run and test a Postman collection directly from the command-line. It is built with extensibility in mind so that you can easily integrate it with your continuous integration servers and build systems.

It monitors availability and performance, gives you simple access to relevant data and raises alerts to keep you in the loop. It was originally created as a fork of the Nagios system monitoring application.

It allows its users to monitor and control a number of processes on UNIX-like operating systems. It shares some of the same goals of programs like launchd, daemontools, and runit. it is meant to be used to control processes related to a project or a customer, and is meant to start like any other program at boot time.

The automatic type-safe REST library for .NET Core, Xamarin and .NET. Heavily inspired by Square's Retrofit library, It turns your REST API into a live interface.

It is a free web debugging proxy for any browser, system or platform. It helps you debug web applications by capturing network traffic between the Internet and test computers. The tool enables you to inspect incoming and outgoing data to monitor and modify requests and responses before the browser receives them.

Stop writing thousands of lines of specification code. Our intuitive visual editors significantly cut down on design time, and are spec agnostic. Generate OAI (Swagger) and RAML specification code on demand.

Super fast HTML 5 2D rendering engine that uses webGL with canvas fallback

Thanos is a set of components that can be composed into a highly available metric system with unlimited storage capacity. It can be added seamlessly on top of existing Prometheus deployments and leverages the Prometheus 2.0 storage format to cost-efficiently store historical metric data in any object storage while retaining fast query latencies. Additionally, it provides a global query view across all Prometheus installations and can merge data from Prometheus HA pairs on the fly.

API Blueprint is simple and accessible to everybody involved in the API lifecycle. Its syntax is concise yet expressive. With API Blueprint you can quickly design and prototype APIs to be created or document and test already deployed mission-critical APIs.

collectd gathers statistics about the system it is running on and stores this information. Those statistics can then be used to find current performance bottlenecks (i.e. performance analysis) and predict future system load (i.e. capacity planning). Or if you just want pretty graphs of your private server and are fed up with some homegrown solution you're at the right place, too.

Cacti is a complete network graphing solution designed to harness the power of RRDTool's data storage and graphing functionality. Cacti provides a fast poller, advanced graph templating, multiple data acquisition methods, and user management features out of the box.

It is a complete, modern, intuitive and scalable API platform that lets you create, securely expose, manage and monetize APIs across clouds so that you and your customers can power digital applications and spur innovation.

Appwrite's open-source platform lets you add Auth, DBs, Functions and Storage to your product and build any application at any scale, own your data, and use your preferred coding languages and tools.

It delivers the only complete open source middleware platform. With its revolutionary componentized design, it is also the only open source platform-as-a-service for private and public clouds available today. With it, seamless migration and integration between servers, private clouds, and public clouds is now a reality.

Sysdig is open source, system-level exploration: capture system state and activity from a running Linux instance, then save, filter and analyze. Sysdig is scriptable in Lua and includes a command line interface and a powerful interactive UI, csysdig, that runs in your terminal. Think of sysdig as strace + tcpdump + htop + iftop + lsof + awesome sauce. With state of the art container visibility on top.

Developed by network and systems engineers who know what it takes to manage today's dynamic IT environments, SolarWinds has a deep connection to the IT community.

Generate real Swagger/OpenAPI 2.0 specifications from a Django Rest Framework API.

Checkmk is a comprehensive solution for IT Monitoring of servers, applications, networks, cloud infrastructures (public, private, hybrid), containers, storage, databases and environment sensors.