REST API for system information
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💻 System API

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System API (sys-API) is a RESTful API to your computers hardware.

Sys-API publishes and monitors values from OSHI with the help of Dropwizard. On Windows the information is supplemented with OpenHardwareMonitor with a little help from OhmJni4Net.

What can it do?

  • Threshold-based monitoring of system values
  • List ongoing threshold violations (events)
  • CPU usage & info
  • Memory usage
  • List running processes
  • List all network interfaces
  • Show info from sensors and fans
  • Motherboard information


    // Static information about the system
    GET     /system
    // Current load of the system
    GET     /system/load
    // An array of (date, system load) entries
    GET     /system/load/history

    // Currently configured monitors
    GET     /monitors
    // Configure a new monitor
    POST    /monitors
    // Remove an existing monitor
    DELETE  /monitors/{id}

    // Get currently ongoing threshold violations, if any.
    GET     /events

    // displays meta info about the Sys-API server
    GET     /

    GET     /cpu
    GET     /cpu/load
    GET     /cpu/load/history
    GET     /drives
    GET     /drives/loads
    GET     /drives/loads/history
    GET     /drives/loads/{name}
    GET     /drives/{name}
    GET     /gpus
    GET     /gpus/loads
    GET     /gpus/loads/history
    GET     /memory
    GET     /memory/history
    GET     /motherboard
    GET     /motherboard/health
    GET     /nics
    GET     /nics/loads
    GET     /nics/loads/history
    GET     /nics/loads/{id}
    GET     /nics/{id}
    GET     /pid
    GET     /processes
    GET     /processes/{pid}
    GET     /system/jvm
    GET     /system/uptime
    GET     /version


The /system endpoint contains accumulated information about the whole system. Then if you want information for just a specific part of the system you can use the part specific endpoint. So for example the cpu temperature and usage is under /cpu. Some things are excluded from /system, such as /system/jvm and /processes since they contain so much information.

Building UIs

The general idea is that each item has a root endpoint that contain static information, like a processors name or the names of the disks. Then each and every item has a /load endpoint that gives you the current load of that item and a /load/history that gives you the load history over time. Disks or network interfaces always have mappable names or ID's between the root and load/history content.

History endpoints also have the ability to limit it's output.

Example: v2/system/load/history?fromDate=2018-09-23T15:11:55.661&toDate=2018-09-23T15:21:25.659

So if you are building a UI on top of this API you can query the root endpoint once or seldom. And then if you want to display load over time you can query the history endpoint once and then continuously poll the load endpoint and append the results to the history collections.


Currently, you can monitor

  • CPU load
  • CPU temperature
  • Memory usage
  • Network up or down

Configuring monitors

You add a monitor by doing a POST call to /monitors with the body of com.krillsson.sysapi.dto.monitor.Monitor:

  "inertiaInSeconds": "10",
  "threshold": "123"

If you exclude the "id" field from the JSON the API will create a new monitor. If you include an ID the API will update the monitor of that ID if it exists or return NOT FOUND/404 if it does not exist.

The response for this call will be the UUID of the monitor that was created:

    "id": "4bd27b5a-b3a2-4716-a7bb-8f0bf9815849"

You can then use this ID to delete or update a monitor.

Inertia: the amount of time in seconds the threshold should be crossed for before triggering a event. The same goes for when transitioning back to below the threshold.

Note: The NETWORK_UP ignores the threshold and uses 1 as value for up and 0 for down.

Note: The cpu, gpu and cpu temp monitors checks if the load goes above the thresholds while the drive and memory onces monitors considers a violation to be when the value drops below a threshold.

Querying for events

Call the /events endpoints to get the currently ongoing threshold violations (events).

The response will be an array of com.krillsson.sysapi.dto.monitor.MonitorEvent:

        "id": "9723c720-4fa0-4497-a08d-8117aa343713",
        "monitorId": "4bd27b5a-b3a2-4716-a7bb-8f0bf9815849",
        "time": 1532602649608,
        "monitorStatus": "START|STOP",
        "threshold": 123,
        "value": 122

The "id" in the response above can be used to delete the events associated with that ID. If you remove a START event with a particular ID, the STOP event for that event will be discarded.


Download the latest release.

  • Windows: unzip the package somewhere convenient and then right click the .bat file and choose Run as administrator
  • *nix: untar or unzip the package and run the .sh file from a terminal

A GUI in JavaFX is in the making

Concerned about memory usage

Change the launcher script to this: java -Xmx256m -Xms128m -jar system-api.jar server configuration.yml


The configuration.yml file is a Dropwizard configuration file.

Basic Authentication:

    username: [change me]
    password: [change me]

Disable the OhmJni extension on Windows:

  enableOhmJniWrapper: false

Enable HTTPS

Forward HTTP to HTTPS:

forwardHttps: true



git clone [this repo] sys-api
mvn clean install
cd server
java -jar target/system-api.jar server configuration.yml


curl -i --user user:password -H "Accept: application/json" -X GET http://localhost:8080/v2/system

Package for distribution in a .zip, tar.gz and tar.bz2:

mvn clean package

And the resulting files should be located in /server/target/


Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.