**A curated list of amazingly awesome Free and Open-Source sysadmin resources.** Please read the [Pull Request template](./.github/PULL_REQUEST_TEMPLATE.md) if you wish to add software and consider [donating](https://github.com/n1trux/awesome-donations) to the FLOSS projects you use regularly. Please consider contributing to fix one of the pinned [issues](https://github.com/awesome-foss/awesome-sysadmin/issues) if your time allows.
- [Apache Ant](https://ant.apache.org/) - Automation build tool, similar to make, a library and command-line tool whose mission is to drive processes described in build files as targets and extension points dependent upon each other. ([Source Code](https://github.com/apache/ant)) `Apache-2.0``Java`
- [Apache Maven](https://maven.apache.org/) - Build automation tool mainly for Java. A software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project's build, reporting and documentation from a central piece of information. ([Source Code](https://github.com/apache/maven)) `Apache-2.0``Java`
- [Bazel](https://www.bazel.io/) - A fast, scalable, multi-language and extensible build system. Used by Google. ([Source Code](https://github.com/bazelbuild/bazel/)) `Apache-2.0``Java`
- [Bolt](https://www.puppet.com/community/open-source/bolt) - You can use Bolt to run one-off tasks, scripts to automate the provisioning and management of some nodes, you can use Bolt to move a step beyond scripts, and make them shareable. ([Source Code](https://github.com/puppetlabs/bolt)) `Apache-2.0``Ruby`
- [GNU Make](https://www.gnu.org/software/make/) - The most popular automation build tool for many purposes, make is a tool which controls the generation of executables and other non-source files of a program from the program's source files. ([Source Code](https://git.savannah.gnu.org/cgit/make.git)) `GPL-3.0``C`
- [Rake](https://ruby.github.io/rake/) - Build automation tool similar to Make, written in and extensible in Ruby. ([Source Code](https://github.com/ruby/rake)) `MIT``Ruby`
- [Amanda](https://www.amanda.org/) - Backup and archive many computers on a network to disk, tape changer/drive or cloud storage. ([Source Code](https://github.com/zmanda/amanda)) `MIT``C`
- [Backupninja](https://0xacab.org/liberate/backupninja) - Lightweight, extensible meta-backup system, provides a centralized way to configure and coordinate many different backup utilities. `GPL-2.0``Shell`
- [BackupPC](https://backuppc.github.io/backuppc/) - High-performance, enterprise-grade system for backing up to a server's disk.. ([Source Code](https://github.com/backuppc/backuppc)) `GPL-3.0``Perl`
- [Bareos](https://www.bareos.org/) - Cross-network backup solution which preserves, archives, and recovers data from all major operating systems. ([Source Code](https://github.com/bareos/bareos)) `AGPL-3.0``C++/C`
- [Barman](https://pgbarman.org) - Backup and Recovery Manager for PostgreSQL. ([Source Code](https://github.com/EnterpriseDB/barman)) `GPL-3.0``Python`
- [Dar](http://dar.linux.free.fr/) - Which stands for Disk ARchive, is a robust and rich featured archiving and backup software of the tar style. ([Source Code](https://github.com/Edrusb/DAR)) `GPL-2.0``C++`
- [Proxmox Backup Server](https://www.proxmox.com/en/proxmox-backup-server) - Proxmox Backup Server is an enterprise-class, client-server backup solution thatis capable of backing up virtual machines, containers, and physical hosts. ([Source Code](https://git.proxmox.com/?p=proxmox-backup.git;a=tree)) `GPL-3.0``Rust`
- [rclone](https://rclone.org/) - Command-line program to sync files and directories to and from different cloud storage providers.. ([Source Code](https://github.com/rclone/rclone)) `MIT``Go`
- [Rdiff-backup](https://rdiff-backup.net/) - Reverse differential backup tool, over a network or locally. ([Source Code](https://github.com/rdiff-backup/rdiff-backup)) `GPL-2.0``Python`
- [EasyBuild](https://easybuild.io/) - EasyBuild builds software and modulefiles for High Performance Computing (HPC) systems in an efficient way. ([Source Code](https://github.com/easybuilders/easybuild-easyconfigs)) `GPL-2.0``Python`
- [Environment Modules](https://cea-hpc.github.io/modules/) - Environment Modules provides for the dynamic modification of a user's environment via modulefiles. ([Source Code](https://github.com/cea-hpc/modules)) `GPL-2.0``Tcl`
- [Lmod](https://www.tacc.utexas.edu/research-development/tacc-projects/lmod) - Lmod is a Lua based module system that easily handles the MODULEPATH Hierarchical problem. ([Source Code](https://github.com/TACC/Lmod)) `MIT``Lua`
- [Eggdrop](https://www.eggheads.org/) - The oldest Internet Relay Chat (IRC) bot still in active development. ([Source Code](https://github.com/eggheads/eggdrop)) `GPL-2.0``C`
- [Errbot](https://errbot.io/) - Plugin based chatbot designed to be easily deployable, extensible and maintainable. ([Source Code](https://github.com/errbotio/errbot)) `GPL-3.0``Python`
[Cloud computing](https://en.wikipedia.org/wiki/Cloud_computing) is the on-demand availability of computer system resources, especially data storage (cloud storage) and computing power, without direct active management by the user.
[Code review](https://en.wikipedia.org/wiki/Code_review) is a software quality assurance activity in which one or several people check a program mainly by viewing and reading parts of its source code.
[Configuration management (CM)](https://en.wikipedia.org/wiki/Configuration_management) is a systems engineering process for establishing and maintaining consistency of a product's performance, functional, and physical attributes with its requirements, design, and operational information throughout its life.
- [CFEngine](https://cfengine.com/) - Configuration management system for automated configuration and maintenance of large-scale computer systems. ([Source Code](https://github.com/cfengine/core)) `GPL-3.0``C`
- [Chef](https://www.chef.io/products/chef-infra) - Configuration management tool using a pure-Ruby, domain-specific language (DSL) for writing system configuration "recipes". ([Source Code](https://github.com/chef/chef)) `Apache-2.0``Ruby`
- [Puppet](https://www.puppet.com/) - Software configuration management tool which includes its own declarative language to describe system configuration. ([Source Code](https://github.com/puppetlabs/puppet)) `Apache-2.0``Ruby/C`
- [Salt](https://docs.saltproject.io/) - Event-driven IT automation, remote task execution, and configuration management software. ([Source Code](https://github.com/saltstack/salt)) `Apache-2.0``Python`
- [Collins](https://tumblr.github.io/collins/) - At Tumblr, it's the infrastructure source of truth and knowledge. ([Source Code](https://github.com/tumblr/collins)) `Apache-2.0``Docker/Scala`
- [i-doit](https://www.i-doit.org/) - IT Documentation and CMDB. `AGPL-3.0``PHP`
- [iTop](https://www.combodo.com/itop-193) - Complete ITIL web based service management tool. ([Source Code](https://sourceforge.net/projects/itop/files/)) `AGPL-3.0``PHP`
- [netbox](https://netbox.dev/) - IP address management (IPAM) and data center infrastructure management (DCIM) tool. ([Demo](https://demo.netbox.dev/), [Source Code](https://github.com/netbox-community/netbox)) `Apache-2.0``Python`
- [Concourse](https://concourse-ci.org/) - Concourse is a CI tool that treats pipelines as first class objects and containerizes every step along the way. ([Demo](https://ci.concourse-ci.org/), [Source Code](https://github.com/concourse/concourse)) `Apache-2.0``Go`
- [drone](https://drone.io/) - Drone is a Continuous Delivery platform built on Docker, written in Go. ([Source Code](https://github.com/drone/drone)) `Apache-2.0``Go`
- [PHP Censor](https://github.com/php-censor/php-censor) - Open source self-hosted continuous integration server for PHP projects. `BSD-2-Clause``PHP`
- [PHPCI](https://www.phptesting.org/) - Free and open source continuous integration specifically designed for PHP. ([Source Code](https://github.com/block8/phpci)) `BSD-2-Clause``PHP`
- [werf](https://werf.io/) - Open Source CI/CD tool for building Docker images and deploying to Kubernetes via GitOps. ([Source Code](https://github.com/werf/werf)) `Apache-2.0``Go`
- [Woodpecker](https://woodpecker-ci.org/) - Community fork of Drone that uses Docker containers. ([Source Code](https://github.com/woodpecker-ci/woodpecker)) `Apache-2.0``Go`
- [Froxlor](https://froxlor.org/) - Lightweight server management software with Nginx and PHP-FPM support. ([Source Code](https://github.com/Froxlor/Froxlor/)) `GPL-2.0``PHP`
- [HestiaCP](https://hestiacp.com/) - Web server control panel (fork of VestaCP). ([Demo](https://demo.hestiacp.com:8083/login/), [Source Code](https://github.com/hestiacp/hestiacp)) `GPL-3.0``PHP/Shell/Other`
- [ISPConfig](https://www.ispconfig.org) - Manage Linux servers directly through your browser. ([Source Code](https://git.ispconfig.org/ispconfig/ispconfig3)) `BSD-3-Clause``PHP`
- [Sentora](https://sentora.org/) - Open-Source Web hosting control panel for Linux, BSD (fork of ZPanel). ([Source Code](https://github.com/sentora/sentora-core)) `GPL-3.0``PHP`
- [Virtualmin](https://www.virtualmin.com/) - Powerful and flexible web hosting control panel for Linux and BSD systems. ([Source Code](https://github.com/virtualmin)) `GPL-3.0``Shell/Perl/Other`
- [Webmin](https://www.webmin.com/) - Web-based interface for system administration for Unix. ([Source Code](https://github.com/webmin/webmin)) `BSD-3-Clause``Perl`
- [Capistrano](https://capistranorb.com/) - Deploy your application to any number of machines simultaneously, in sequence or as a rolling set via SSH (rake based). ([Source Code](https://github.com/capistrano/capistrano)) `MIT``Ruby`
- [CloudSlang](https://www.cloudslang.io/) - Flow-based orchestration tool for managing deployed applications, with Docker capabilities. ([Source Code](https://github.com/CloudSlang/score)) `Apache-2.0``Java`
- [CloudStack](https://cloudstack.apache.org/) - Cloud computing software for creating, managing, and deploying infrastructure cloud services. ([Source Code](https://github.com/apache/cloudstack)) `Apache-2.0``Java/Python`
- [Cobbler](https://cobbler.github.io/) - Cobbler is a Linux installation server that allows for rapid setup of network installation environments. ([Source Code](https://github.com/cobbler/cobbler)) `GPL-2.0``Python`
- [Fabric](https://www.fabfile.org/) - Python library and cli tool for streamlining the use of SSH for application deployment or systems administration tasks. ([Source Code](https://github.com/fabric/fabric)) `BSD-2-Clause``Python`
- [Mina](http://nadarei.co/mina/) - Really fast deployer and server automation tool (rake based). ([Source Code](https://github.com/mina-deploy/mina)) `MIT``Ruby`
- [munki](https://www.munki.org/munki/) - Webserver-based repository of packages and package metadata, that allows macOS administrators to manage software installs. ([Source Code](https://github.com/munki/munki)) `Apache-2.0``Python`
- [Overcast](https://andrewchilds.github.io/overcast/) - Deploy VMs across different cloud providers, and run commands and scripts across any or all of them in parallel via SSH. ([Source Code](https://github.com/andrewchilds/overcast)) `MIT``Nodejs`
- [Diagrams.net](https://app.diagrams.net/) - A.K.A. [Draw.io](https://app.diagrams.net/). Easy to use Diagram UI with a plethora of templates. ([Source Code](https://github.com/jgraph/drawio)) `Apache-2.0``JavaScript/Docker`
- [DrawThe.Net](http://go.drawthe.net/) - Javascript tool that uses a YAML-formatted input to programmatically create large, complex, and visually solid diagrams. ([Source Code](https://github.com/cidrblock/drawthe.net)) `MIT``JavaScript`
- [Mermaid](https://mermaid-js.github.io/mermaid-live-editor/) - Javascript module with a unique, easy, shorthand syntax. Integrates into several other tools like Grafana. ([Source Code](https://github.com/mermaid-js/mermaid-live-editor)) `MIT``Nodejs/Docker`
- [DRBD](https://linbit.com/drbd/) - Distributed replicated storage system, implemented as a Linux kernel driver. ([Source Code](https://github.com/LINBIT/drbd)) `GPL-2.0``C`
- [GlusterFS](https://www.gluster.org/) - Software-defined distributed storage that can scale to several petabytes, with interfaces for object, block and file storage. ([Source Code](https://github.com/gluster/glusterfs)) `GPL-2.0/LGPL-3.0``C`
- [Hadoop Distributed Filesystem (HDFS)](https://hadoop.apache.org/) - Distributed file system that provides high-throughput access to application data. ([Source Code](https://github.com/apache/hadoop)) `Apache-2.0``Java`
- [JuiceFS](https://juicefs.com/) - Distributed POSIX file system built on top of Redis and S3. ([Source Code](https://github.com/juicedata/juicefs)) `Apache-2.0``Go`
- [Kubo](https://github.com/ipfs/kubo) - Implementation of IPFS, a global, versioned, peer-to-peer filesystem that seeks to connect all computing devices with the same system of files. `Apache-2.0/MIT``Go`
- [Minio](https://min.io/) - High-performance, S3 compatible object store built for large scale AI/ML, data lake and database workloads. ([Source Code](https://github.com/minio/minio)) `AGPL-3.0``Go`
- [Perkeep](https://perkeep.org/) - A set of open source formats, protocols, and software for modeling, storing, searching, sharing and synchronizing data (previously Camlistore). ([Source Code](https://github.com/perkeep/perkeep)) `Apache-2.0``C`
- [TahoeLAFS](https://tahoe-lafs.org/trac/tahoe-lafs) - Secure, decentralized, fault-tolerant, peer-to-peer distributed data store and distributed file system. ([Source Code](https://github.com/tahoe-lafs/tahoe-lafs)) `GPL-2.0``Python`
- [XtreemFS](https://www.xtreemfs.org/) - Distributed, replicated and fault-tolerant file system for federated IT infrastructures.. ([Source Code](https://github.com/xtreemfs/xtreemfs)) `BSD-3-Clause``Java`
- [Atomia DNS](https://github.com/atomia/atomiadns/) - DNS management system. `ISC``Perl`
- [Designate](https://wiki.openstack.org/wiki/Designate) - DNSaaS services for OpenStack. ([Source Code](https://opendev.org/openstack/designate)) `Apache-2.0``Python`
- [DNSControl](https://stackexchange.github.io/dnscontrol/) - Synchronize your DNS to multiple providers from a simple DSL. ([Source Code](https://github.com/StackExchange/dnscontrol)) `MIT``Go/Docker`
- [DomainMOD](https://domainmod.org) - Manage your domains and other internet assets in a central location. ([Source Code](https://github.com/domainmod/domainmod)) `GPL-3.0``PHP`
- [nsupdate.info](https://www.nsupdate.info/) - Dynamic DNS service. ([Demo](https://www.nsupdate.info/account/register/), [Source Code](https://github.com/nsupdate-info/nsupdate.info)) `BSD-3-Clause``Python`
- [octoDNS](https://github.com/github/octodns) - DNS as code - Tools for managing DNS across multiple providers. `MIT``Python`
- [Poweradmin](https://www.poweradmin.org/) - Web-based DNS control panel for PowerDNS server. ([Source Code](https://github.com/poweradmin/poweradmin)) `GPL-3.0``PHP`
- [SPF Toolbox](https://spftoolbox.com) - Application to look up DNS records such as SPF, MX, Whois, and more. ([Source Code](https://github.com/charlesabarnes/SPFtoolbox)) `MIT``PHP`
- [djbdns](https://cr.yp.to/djbdns.html) - A collection of DNS applications, including tinydns. ([Source Code](https://salsa.debian.org/debian/djbdns)) `CC0-1.0``C`
- [dnsmasq](https://www.thekelleys.org.uk/dnsmasq/doc.html) - Provides network infrastructure for small networks: DNS, DHCP, router advertisement and network boot. ([Source Code](https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=tree)) `GPL-2.0``C`
- [Knot](https://www.knot-dns.cz/) - High performance authoritative-only DNS server. ([Source Code](https://gitlab.nic.cz/knot/knot-dns)) `GPL-3.0``C`
- [NSD](https://www.nlnetlabs.nl/projects/nsd/about/) - Authoritative DNS name server developed speed, reliability, stability and security. ([Source Code](https://github.com/NLnetLabs/nsd)) `BSD-3-Clause``C`
- [PowerDNS Authoritative Server](https://doc.powerdns.com/authoritative/) - Versatile nameserver which supports a large number of backends. ([Source Code](https://github.com/PowerDNS/pdns)) `GPL-2.0``C++`
- [Unbound](https://nlnetlabs.nl/projects/unbound/about/) - Validating, recursive, and caching DNS resolver. ([Source Code](https://github.com/NLnetLabs/unbound)) `BSD-3-Clause``C`
- [Yadifa](https://www.yadifa.eu/) - Clean, small, light and RFC-compliant name server implementation developed from scratch by .eu. ([Source Code](https://github.com/yadifa/yadifa)) `BSD-3-Clause``C`
- [Atom Community](https://github.com/atom-community/atom) - A fork of [atom](https://github.com/atom/atom) A hackable text editor from Github. `MIT``JavaScript`
- [Brackets](https://brackets.io/) - Code editor for web designers and front-end developers. ([Source Code](https://github.com/brackets-cont/brackets)) `MIT``JavaScript`
- [Eclipse](https://www.eclipse.org/) - IDE written in Java with an extensible plug-in system. ([Source Code](https://git.eclipse.org/c/)) `EPL-1.0``Java`
- [Geany](https://www.geany.org/) - GTK2 text editor. ([Source Code](https://github.com/geany/geany)) `GPL-2.0``C/C++`
- [GNU Emacs](https://www.gnu.org/software/emacs/) - An extensible, customizable text editor-and more. ([Source Code](https://github.com/emacs-mirror/emacs)) `GPL-3.0``C`
- [ICEcoder](https://icecoder.net/) - Code editor awesomeness, built with common web languages. ([Demo](http://demo.icecoder.net), [Source Code](https://github.com/icecoder/ICEcoder)) `MIT``PHP`
- [Micro](https://micro-editor.github.io/) - A modern and intuitive terminal-based text editor. ([Source Code](https://github.com/zyedidia/micro)) `MIT``Go`
- [Vim](https://www.vim.org) - A highly configurable text editor built to enable efficient editing. ([Source Code](https://github.com/vim/vim)) `Vim``C`
- [VSCodium](https://vscodium.com/) - An open source cross-platform extensible code editor based on [VS Code by Microsoft](https://code.visualstudio.com/) removing their non-free additions. ([Source Code](https://github.com/VSCodium/vscodium)) `MIT``TypeScript`
[Identity management](https://en.wikipedia.org/wiki/Identity_management) (IdM), also known as identity and access management (IAM or IdAM), is a framework of policies and technologies to ensure that the right users (that are part of the ecosystem connected to or within an enterprise) have the appropriate access to technology resources.
[Lightweight Directory Access Protocol (LDAP)](https://en.wikipedia.org/wiki/Lightweight_Directory_Access_Protocol) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an Internet Protocol (IP) network.
- [389 Directory Server](https://www.port389.org/) - Enterprise-class Open Source LDAP server for Linux. ([Source Code](https://github.com/389ds/389-ds-base)) `GPL-3.0``C`
- [Apache Directory Server](https://directory.apache.org/apacheds/) - Extensible and embeddable directory server, certified LDAPv3 compatible, with Kerberos 5 and Change Password Protocol support, triggers, stored procedures, queues and views. ([Source Code](https://github.com/apache/directory-server)) `Apache-2.0``Java`
- [FreeIPA](https://www.freeipa.org/) - Integrated security information management solution combining Linux (Fedora), 389 Directory Server, Kerberos, NTP, DNS, and Dogtag Certificate System (web interface and command-line administration tools). ([Source Code](https://pagure.io/freeipa)) `GPL-3.0``Python/C/JavaScript`
- [FreeRADIUS](https://freeradius.org/) - Multi-protocol policy server (radiusd) that implements RADIUS, DHCP, BFD, and ARP and associated client/PAM library/Apache module. ([Source Code](https://github.com/FreeRADIUS/freeradius-server)) `GPL-2.0``C`
- [lldap](https://github.com/nitnelave/lldap) - Light (simplified) LDAP implementation with a simple, intuitive web interface and GraphQL support. `GPL-3.0``Rust`
[Single sign-on (SSO)](https://en.wikipedia.org/wiki/Single_sign-on) is an authentication scheme that allows a user to log in with a single ID to any of several related, yet independent, software systems.
- [Authelia](https://www.authelia.com/) - The Single Sign-On Multi-Factor portal for web apps. ([Source Code](https://github.com/authelia/authelia)) `Apache-2.0``Go`
- [Authentik](https://goauthentik.io/) - Flexible identity provider with support for different protocols. (OAuth 2.0, SAML, LDAP and Radius). ([Source Code](https://github.com/goauthentik/authentik)) `MIT``Python`
- [KeyCloak](https://www.keycloak.org) - Open Source Identity and Access Management. ([Source Code](https://github.com/keycloak/keycloak)) `Apache-2.0``Java`
- [Fusion Directory](https://www.fusiondirectory.org) - Improve the Management of the services and the company directory based on OpenLDAP. ([Source Code](https://github.com/fusiondirectory/fusiondirectory)) `GPL-2.0``PHP`
- [Indieauth](https://indieauth.com/) - Sign in with your domain name (using the rel-me-auth protocol). ([Source Code](https://github.com/aaronpk/IndieAuth.com)) `Apache-2.0``Ruby`
- [LDAP Account Manager (LAM)](https://www.ldap-account-manager.org/lamcms/) - Web frontend for managing entries (e.g. users, groups, DHCP settings) stored in an LDAP directory. ([Source Code](https://github.com/LDAPAccountManager/lam/)) `GPL-3.0``PHP`
- [Libravatar](https://www.libravatar.org/) - Libravatar is a service which delivers your avatar (profile picture) to other websites. ([Source Code](https://git.linux-kernel.at/oliver/ivatar/)) `AGPL-3.0``Python`
- [Pomerium](https://www.pomerium.io/) - An identity and context aware access-proxy inspired by BeyondCorp. ([Source Code](https://github.com/pomerium/pomerium)) `Apache-2.0``Docker/Go`
- [GLPI](https://www.glpi-project.org/) - Information Resource-Manager with an additional Administration Interface. ([Source Code](https://github.com/glpi-project/glpi)) `GPL-3.0``PHP`
- [OCS Inventory NG](https://ocsinventory-ng.org/) - Asset management and deployment solution for all devices in your IT Department. ([Source Code](https://github.com/OCSInventory-NG)) `GPL-2.0``PHP/Perl`
- [OPSI](https://www.opsi.org) - Hardware and software inventory, client management, deployment, and patching for Linux and Windows. ([Source Code](https://github.com/opsi-org/)) `GPL-3.0/AGPL-3.0``OVF/Python`
- [RackTables](https://racktables.org/) - Datacenter and server room asset management like document hardware assets, network addresses, space in racks, networks configuration. ([Demo](https://www.racktables.org/demo.php), [Source Code](https://github.com/RackTables/racktables)) `GPL-2.0``PHP`
- [Ralph](https://ralph.allegro.tech/) - Asset management, DCIM and CMDB system for large Data Centers as well as smaller LAN networks. ([Demo](https://github.com/allegro/ralph#live-demo), [Source Code](https://github.com/allegro/ralph)) `Apache-2.0``Python/Docker`
- [Flume](https://flume.apache.org/) - Distributed, reliable, and available service for efficiently collecting, aggregating, and moving large amounts of log data. ([Source Code](https://github.com/apache/flume)) `Apache-2.0``Java`
- [GoAccess](https://goaccess.io/) - Real-time web log analyzer and interactive viewer that runs in a terminal or through the browser. ([Source Code](https://github.com/allinurl/goaccess)) `MIT``C`
- [Loki](https://grafana.com/oss/loki/) - Log aggregation system designed to store and query logs from all your applications and infrastructure. ([Source Code](https://github.com/grafana/loki)) `AGPL-3.0``Go`
An [email client](https://en.wikipedia.org/wiki/Email_client), email reader or, more formally, message user agent (MUA) or mail user agent is a computer program used to access and manage a user's email.
- [Claws Mail](http://www.claws-mail.org/) - Old school email client (and news reader), based on GTK+. ([Source Code](https://git.claws-mail.org/?p=claws.git;a=tree)) `GPL-3.0``C`
- [Sylpheed](https://sylpheed.sraoss.jp/en/) - Still developed predecessor to Claws Mail, lightweight mail client. ([Source Code](https://github.com/sylpheed-mail/sylpheed)) `GPL-2.0``C`
- [Thunderbird](https://www.thunderbird.net/) - Free email application that's easy to set up and customize. ([Source Code](https://hg.mozilla.org/comm-central/file)) `MPL-2.0``C/C++`
- [Beats](https://www.elastic.co/beats/) - Single-purpose data shippers that send data from hundreds or thousands of machines and systems to Logstash or Elasticsearch. ([Source Code](https://github.com/elastic/beats)) `Apache-2.0``Go`
- [Collectd](https://collectd.org/) - System statistics collection daemon. ([Source Code](https://github.com/collectd/collectd)) `MIT``C`
- [Diamond](https://github.com/python-diamond/Diamond) - Daemon that collects system metrics and publishes them to Graphite (and others). `MIT``Python`
- [Grafana](https://grafana.com/) - A Graphite & InfluxDB Dashboard and Graph Editor. ([Source Code](https://github.com/grafana/grafana)) `AGPL-3.0``Go`
- [RRDtool](https://oss.oetiker.ch/rrdtool/) - Industry standard, high performance data logging and graphing system for time series data. ([Source Code](https://github.com/oetiker/rrdtool-1.x)) `GPL-2.0``C`
- [Statsd](https://github.com/etsy/statsd/) - Daemon that listens for statistics like counters and timers, sent over UDP or TCP, and sends aggregates to one or more pluggable backend services. `MIT``Nodejs`
- [tcollector](http://opentsdb.net/docs/build/html/user_guide/utilities/tcollector.html) - Gathers data from local collectors and pushes the data to OpenTSDB. ([Source Code](https://github.com/OpenTSDB/tcollector/)) `LGPL-3.0/GPL-3.0``Python`
- [Telegraf](https://github.com/influxdata/telegraf) - Plugin-driven server agent for collecting, processing, aggregating, and writing metrics. `MIT``Go`
- [Chocolatey](https://chocolatey.org/) - The package manager for Windows. ([Source Code](https://github.com/chocolatey/choco)) `Apache-2.0``C#/PowerShell`
- [Clonezilla](https://clonezilla.org/) - Partition and disk imaging/cloning program. ([Source Code](https://clonezilla.org/downloads/src/)) `GPL-2.0``Perl/Shell/Other`
- [DadaMail](https://dadamailproject.com/) - Mailing List Manager, written in Perl. ([Source Code](https://sourceforge.net/projects/dadamail/files/)) `GPL-2.0``Perl`
- [Adagios](http://adagios.org/) - Web based Nagios interface for configuration and monitoring (replacement to the standard interface), and a REST interface. ([Source Code](https://github.com/opinkerfi/adagios)) `AGPL-3.0``Docker/Python`
- [Bloonix](https://bloonix-monitoring.org/) - Bloonix is a monitoring solution that helps businesses to ensure high availability and performance. ([Source Code](https://github.com/bloonix)) `GPL-3.0``Perl`
- [checkmk](https://checkmk.com/) - Comprehensive solution for monitoring of applications, servers, and networks. ([Source Code](https://github.com/Checkmk/checkmk)) `GPL-2.0``Python/PHP`
- [dashdot](https://github.com/MauriceNino/dashdot) - A simple, modern server dashboard for smaller private servers. ([Demo](https://dash.mauz.dev/)) `MIT``Nodejs/Docker`
- [EdMon](https://github.com/Edraens/EdMon) - A command-line monitoring application helping you to check that your hosts and services are available, with notifications support. `MIT``Java`
- [eZ Server Monitor](https://www.ezservermonitor.com) - A lightweight and simple dashboard monitor for Linux, available in Web and Bash application. ([Source Code](https://github.com/shevabam/ezservermonitor-web)) `GPL-3.0``PHP/Shell`
- [glances](https://nicolargo.github.io/glances/) - Open-source, cross-platform real-time monitoring tool with CLI and web dashboard interfaces and many exporting options. ([Source Code](https://github.com/nicolargo/glances)) `GPL-3.0``Python`
- [Icinga](https://www.icinga.com/) - Nagios fork that has since lapped nagios several times. Comes with the possibility of clustered monitoring. ([Source Code](https://github.com/Icinga/icinga2)) `GPL-2.0``C++`
- [LibreNMS](https://www.librenms.org) - Fully featured network monitoring system that provides a wealth of features and device support. ([Source Code](https://github.com/librenms/librenms)) `GPL-3.0``PHP`
- [Monit](https://mmonit.com/monit/#home) - Small utility for managing and monitoring Unix systems. ([Source Code](https://bitbucket.org/tildeslash/monit/src/master/)) `AGPL-3.0``C`
- [Naemon](https://www.naemon.org/) - Network monitoring tool based on the Nagios 4 core with performance enhancements and new features. ([Source Code](https://github.com/naemon/naemon-core)) `GPL-2.0``C`
- [Netdata](https://www.netdata.cloud/) - Distributed, real-time, performance and health monitoring for systems and applications. Runs on Linux, FreeBSD, and MacOS. ([Source Code](https://github.com/netdata/netdata)) `GPL-3.0``C`
- [NetXMS](https://www.netxms.org/) - Open Source network and infrastructure monitoring and management. ([Source Code](https://github.com/netxms/netxms)) `LGPL-3.0/GPL-3.0``Java/C++/C`
- [Observium Community Edition](http://www.observium.org/) - Network monitoring and management platform that provides real-time insight into network health and performance. `QPL-1.0``PHP`
- [openITCOCKPIT Community Edition](https://openitcockpit.io/) - Monitoring Suite featuring seamless integrations with Naemon, Checkmk, Grafana and more. ([Demo](https://demo.openitcockpit.io/), [Source Code](https://github.com/it-novum/openITCOCKPIT)) `GPL-3.0``deb/Docker`
- [PHP Server Monitor](https://www.phpservermonitor.org/) - Open source tool to monitor your servers and websites. ([Source Code](https://github.com/phpservermon/phpservermon)) `GPL-3.0``PHP`
- [PhpSysInfo](https://phpsysinfo.github.io/phpsysinfo/) - A customizable PHP script that displays information about your system nicely. ([Source Code](https://github.com/phpsysinfo/phpsysinfo)) `GPL-2.0``PHP`
- [Prometheus](https://prometheus.io/) - Service monitoring system and time series database. ([Source Code](https://github.com/prometheus/prometheus)) `Apache-2.0``Go`
- [Status](https://github.com/dani3l0/Status) - Simple and lightweight system monitoring tool for small homeservers with a pleasant web interface. ([Demo](https://status-ksk5.onrender.com/)) `MIT``Python`
- [Thruk](https://www.thruk.org/) - Multibackend monitoring web interface with support for Naemon, Nagios, Icinga and Shinken. ([Source Code](https://github.com/sni/Thruk)) `GPL-1.0``Perl`
- [Zabbix](https://www.zabbix.com/) - Enterprise-class software for monitoring of networks and applications. ([Source Code](https://git.zabbix.com/projects/ZBX/repos/zabbix/browse)) `GPL-2.0``C`
- [OpenWISP](https://openwisp.org/) - Open Source Network Management System for OpenWRT based routers and access points. ([Demo](https://openwisp.org/demo.html), [Source Code](https://github.com/openwisp)) `GPL-3.0``Python`
- [phpIPAM](https://phpipam.net/) - Open source IP address management with PowerDNS integration. ([Source Code](https://github.com/phpipam/phpipam)) `GPL-3.0``PHP`
- [RANCID](https://www.shrubbery.net/rancid/) - Monitor network devices configuration and maintain history of changes. ([Source Code](https://github.com/haussli/rancid)) `BSD-3-Clause``Perl/Shell`
A [package manager](https://en.wikipedia.org/wiki/Package_manager) or package-management system is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs for a computer in a consistent manner.
- [fpm](https://fpm.readthedocs.io/en/latest/) - Versatile multi format package creator. ([Source Code](https://github.com/jordansissel/fpm)) `MIT``Ruby`
- [omnibus-ruby](https://github.com/chef/omnibus) - Easily create full-stack installers for your project across a variety of platforms. `Apache-2.0``Ruby`
- [tito](https://github.com/dgoodwin/tito) - Builds RPMs for git-based projects. `GPL-2.0``Python`
[Message queues](https://en.wikipedia.org/wiki/Message_queue) and [message broker](https://en.wikipedia.org/wiki/Message_broker) software, typically used for inter-process communication (IPC), or for inter-thread communication within the same process.
- [Remmina](https://www.remmina.org/) - Feature-rich remote desktop application for linux and other unixes. ([Source Code](https://gitlab.com/Remmina/Remmina)) `GPL-2.0``C`
- [X2go](https://wiki.x2go.org/doku.php) - X2Go is an open source remote desktop software for Linux that uses the NoMachine/NX technology protocol. ([Source Code](https://code.x2go.org/gitweb)) `GPL-2.0``Perl`
- [DD-WRT](https://dd-wrt.com/) - A Linux-based firmware for wireless routers and access points, originally designed for the Linksys WRT54G series. ([Source Code](https://svn.dd-wrt.com/)) `GPL-2.0``C`
- [OpenWrt](https://openwrt.org/) - A Linux-based router featuring Mesh networking, IPS via snort and AQM among many other features. ([Source Code](https://git.openwrt.org/openwrt/openwrt.git)) `GPL-2.0``C`
- [OPNsense](https://opnsense.org/) - An open source FreeBSD-based firewall and router with traffic shaping, load balancing, and virtual private network capabilities. ([Source Code](https://github.com/opnsense)) `BSD-2-Clause``C/PHP`
- [pfSense CE](https://www.pfsense.org/) - Free network firewall distribution, based on the FreeBSD operating system with a custom kernel and including third party free software packages for additional functionality. ([Source Code](https://github.com/pfsense/pfsense)) `Apache-2.0``Shell/PHP/Other`
[Service discovery](https://en.wikipedia.org/wiki/Service_discovery) is the process of automatically detecting devices and services on a computer network.
- [Consul](https://www.consul.io/) - Consul is a tool for service discovery, monitoring and configuration. ([Source Code](https://github.com/hashicorp/consul)) `MPL-2.0``Go`
- [etcd](https://etcd.io/) - Distributed K/V-Store, authenticating via SSL PKI and a REST HTTP Api for shared configuration and service discovery. ([Source Code](https://github.com/coreos/etcd)) `Apache-2.0``Go`
- [ZooKeeper](https://zookeeper.apache.org/) - ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. ([Source Code](https://github.com/apache/zookeeper)) `Apache-2.0``Java/C++`
- [Docker](https://www.docker.com/) - Platform for developers and sysadmins to build, ship, and run distributed applications. ([Source Code](https://www.docker.com/community/open-source/)) `Apache-2.0``Go`
- [LXC](https://linuxcontainers.org/lxc/) - Userspace interface for the Linux kernel containment features. ([Source Code](https://github.com/lxc/lxc)) `GPL-2.0``C`
- [LXD](https://linuxcontainers.org/lxd/) - Container "hypervisor" and a better UX for LXC. ([Source Code](https://github.com/lxc/lxd)) `Apache-2.0``Go`
- [Podman](https://podman.io) - Daemonless container engine for developing, managing, and running OCI Containers on your Linux System. Containers can either be run as root or in rootless mode. Simply put: `alias docker=podman`. ([Source Code](https://github.com/containers/podman)) `Apache-2.0``Go`
- [systemd-nspawn](https://www.freedesktop.org/software/systemd/man/systemd-nspawn.html) - Lightweight, chroot-like, environment to run an OS or command directly under systemd. ([Source Code](https://github.com/systemd/systemd)) `GPL-2.0``C`
[Uptime](https://en.wikipedia.org/wiki/Uptime) is a measure of system reliability, expressed as the percentage of time a machine, typically a computer, has been working and available.
- [mitmproxy](https://mitmproxy.org/) - A Python tool used for intercepting, viewing and modifying network traffic. Invaluable in troubleshooting certain problems. ([Source Code](https://github.com/mitmproxy/mitmproxy)) `MIT``Python`
- [mtr](https://www.bitwizard.nl/mtr/) - Network utility that combines traceroute and ping. ([Source Code](https://github.com/traviscross/mtr)) `GPL-2.0``C`
- [perf-tools](https://github.com/brendangregg/perf-tools) - Performance analysis tools based on Linux perf_events (aka perf) and ftrace. `GPL-2.0``Shell`
- [Sysdig](https://www.sysdig.com/) - Capture system state and activity from a running Linux instance, then save, filter and analyze. ([Source Code](https://github.com/draios/sysdig)) `Apache-2.0``Docker/Lua/C`
- [Darcs](https://darcs.net/) - Cross-platform version control system, like git, mercurial or svn but with a very different approach: focus on changes rather than snapshots. ([Source Code](https://darcs.net/releases/)) `GPL-2.0``Haskell`
- [Fossil](https://www.fossil-scm.org/) - Distributed version control with built-in wiki and bug tracking. ([Source Code](https://www.fossil-scm.org/home/dir?ci=trunk)) `BSD-2-Clause``C`
- [Git](https://git-scm.com/) - Distributed revision control and source code management (SCM) with an emphasis on speed. ([Source Code](https://github.com/git/git)) `GPL-2.0``C`
- [Ganeti](https://www.ganeti.org/) - Cluster virtual server management software tool built on top of KVM and Xen. ([Source Code](https://github.com/ganeti/ganeti)) `BSD-2-Clause``Python/Haskell`
- [KVM](https://www.linux-kvm.org) - Linux kernel virtualization infrastructure. ([Source Code](https://git.kernel.org/pub/scm/virt/kvm/kvm.git/)) `GPL-2.0/LGPL-2.0``C`
- [OpenNebula](https://opennebula.org/) - Build and manage enterprise clouds for virtualized services, containerized applications and serverless computing. ([Source Code](https://github.com/OpenNebula/one)) `Apache-2.0``C++`
- [Packer](https://www.packer.io/) - A tool for creating identical machine images for multiple platforms from a single source configuration. ([Source Code](https://github.com/hashicorp/packer)) `MPL-2.0``Go`
- [QEMU](https://www.qemu.org/) - QEMU is a generic machine emulator and virtualizer. ([Source Code](https://gitlab.com/qemu-project/qemu)) `LGPL-2.1``C`
- [Vagrant](https://www.vagrantup.com/) - Tool for building complete development environments. ([Source Code](https://github.com/hashicorp/vagrant)) `BUSL-1.1``Ruby`
- [Dockovpn](https://dockovpn.io) - Out-of-the-box stateless dockerized OpenVPN server which starts in less than 2 seconds. ([Source Code](https://github.com/dockovpn/dockovpn)) `GPL-2.0``Docker`
- [Firezone](https://www.firez.one/) - WireGuard based VPN Server and Firewall. ([Source Code](https://github.com/firezone/firezone)) `Apache-2.0``Docker`
- [Headscale](https://github.com/juanfont/headscale) - Self-hostable fork of [Tailscale](https://tailscale.com), cross-platform clients, simple to use, built-in (currently experimental) monitoring tools. `BSD-3-Clause``Go`
- [Nebula](https://github.com/slackhq/nebula) - A scalable p2p VPN with a focus on performance, simplicity and security. `MIT``Go`
- [PiVPN](https://www.pivpn.io/) - The simplest way to setup and manage a VPN, designed for Raspberry Pi. ([Source Code](https://github.com/pivpn/pivpn)) `MIT``Shell`
- [WireGuard](https://www.wireguard.com/) - Very fast VPN based on elliptic curve and public key crypto. ([Source Code](https://www.wireguard.com/repositories/)) `GPL-2.0``C`
- [Algernon](https://algernon.roboticoverlords.org/) - Small self-contained pure-Go web server with Lua, Markdown, HTTP/2, QUIC, Redis and PostgreSQL support. ([Source Code](https://github.com/xyproto/algernon)) `BSD-3-Clause``Go`
- [Apache HTTP Server](https://httpd.apache.org/) - Secure, efficient and extensible server that provides HTTP services in sync with the current HTTP standards. ([Source Code](https://svn.apache.org/viewvc/httpd/httpd/branches/2.4.x/)) `Apache-2.0``C`
- [Caddy](https://caddyserver.com/) - Powerful, enterprise-ready, open source web server with automatic HTTPS. ([Source Code](https://github.com/caddyserver/caddy)) `Apache-2.0``Go`
- [HAProxy](https://www.haproxy.org/) - Very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications. ([Source Code](https://git.haproxy.org/?p=haproxy.git;a=tree)) `GPL-2.0``C`
- [Hiawatha](https://www.hiawatha-webserver.org/) - An advanced and secure webserver for Unix. ([Source Code](https://gitlab.com/hsleisink/hiawatha)) `GPL-2.0``C`
- [Lighttpd](https://www.lighttpd.net/) - Secure, fast, compliant, and very flexible web server that has been optimized for high-performance environments. ([Source Code](https://git.lighttpd.net/lighttpd/lighttpd1.4)) `BSD-3-Clause``C`
- [Nginx](https://nginx.org/en/) - HTTP and reverse proxy server, mail proxy server, and generic TCP/UDP proxy server. ([Source Code](https://hg.nginx.org/nginx/file/tip)) `BSD-2-Clause``C`
- [EPEL](https://fedoraproject.org/wiki/EPEL) - Repository for RHEL and compatibles (CentOS, Scientific Linux).
- [IUS](https://ius.io/) - Community project that provides RPM packages for newer versions of select software for Enterprise Linux distributions.
- [Remi](http://rpms.famillecollet.com/) - Repository with LAMP updated packages for RHEL/Centos/Fedora.
- [Software Collections](https://www.softwarecollections.org) - Community Release of [Red Hat Software Collections](https://access.redhat.com/documentation/en/red-hat-software-collections/). Provides updated packages of Ruby, Python, etc. for CentOS/Scientific Linux 6.x.
- [Cloud Native Software Landscape](https://landscape.cncf.io/card-mode?license=open-source&grouping=category) - Compilation of software and tools for cloud computing.
- [Digital Ocean Tutorials](https://www.digitalocean.com/community/tutorials) - 6,000+ tutorials for getting the basics of certain applications/tools/systems administration topics.
