RT from BestPractical <a href="https://www.bestpractical.com/rt/" rel="nofollow">https://www.bestpractical.com/rt/</a>. Extremely extensible and robust, can be used for all kinds of things beyond just ticket tracking (change control approval workflows, knowledge bases, asset tracking, CRM and automation plugins). The king of ticket trackers, could be at the heart of any organisation.<p>Prosody <a href="https://prosody.im/" rel="nofollow">https://prosody.im/</a>. Open source XMPP server with support for MUCs and all the usual XMPP stuff. Best way for teams to communicate. Extend it with plugins for your NMS and so on to get alerts in realtime.<p>Nagios <a href="https://www.nagios.org/" rel="nofollow">https://www.nagios.org/</a>. Solid (if a little fiddly) monitoring / alerting solution. Works best if you write your own plugins and use check_by_ssh instead of NRPE.<p>bcfg2 <a href="http://bcfg2.org/" rel="nofollow">http://bcfg2.org/</a>. Configuration management that makes sense. Tidy and well defined "model" for how configuration should be managed, sensible defaults and a bunch of useful powerful features.<p>I could go on but there are some of my all-time favourites.
Come on folks, don't just list the command line tools that come with your Linux distro :)<p>Let's talk about the big packages that bring value to organisations.
Rails<p>ElasticSearch (And Kibana, holy shit)<p>MySQL<p>React<p>Ractive<p>Ubuntu<p>NGINX<p>Redis<p>We stand on the backs of giants. Yet, for some reason, corporations feel entitled to not give back. Modern computing lives by open source. Companies should be obliged to contribute similarly.
Phabricator for task managment, project management, and code reviews. It's open source, great software, and has a fun personality great for internal use.
A bit different from the rest, is `repo`, from AOSP: <a href="https://source.android.com/source/downloading.html" rel="nofollow">https://source.android.com/source/downloading.html</a><p>We run dozens of microservices and have nearly 100 git repositories. Using `repo`, every dev has every repo in consistent (relative) path from each other. It also greatly simplifies cross-cutting changes across repositories, and staying in sync (`repo sync` updates all repos all at once.)<p>I also use it to manage my dotfiles: github.com/grahamc/manifest<p>Second: Go.CD (<a href="https://www.go.cd/" rel="nofollow">https://www.go.cd/</a>) -- applying build templates to our 100 repositories has greatly simplified our management of the repositories. Using pipelines has added deep visibility into what is deployed where. I love Go.CD.
HAProxy: <a href="http://www.haproxy.org/" rel="nofollow">http://www.haproxy.org/</a><p>The configuration language leaves much to be desired ... but it's otherwise a fantastic piece of software. It's the most configurable, full-featured, stable, and fast proxy server I've ever worked with.
For us the list is very long, beginning with debian and ubuntu. Elasticsearch, redis, haproxy, mongodb, postgressql ... really too many to list. Of these certainly elasticsearch, redis, and haproxy are best in class in my opinion, and all the tools we use are proven performers with solid community support.
The question needs expansion.
What is the OP's definition of best? Why does it matter to the OP that it's open source (would your org contribute back)? Would specific family of licenses matter? And in what problem domain do the tools be used for?<p>I'm guessing most of HN's audience would be using some form of OSS. The coverage of the comments here is large: devops tools, programming tools, libraries, productivity, etc.<p>Our own org uses a lot of open source components, from desktops, office suite, dev environments, server OSes, programming platforms, libraries, databases, CMSes, heck, does Android count?<p>More context is better.
<sigh> Not a <i>single</i> tool we use is open source. Mainly because with an open source application there's no one source for security to go to and ask for a letter certifying the safety of the software.<p>I wish I were kidding.
GCC
GDB
VTK
OpenCV<p>I work for big monolithic company (not a software company). Most of the libraries and dev tools the engineers in my dept use are open source unfortunately the environment they run on isn't.
Spark has improved our ETL jobs by orders of magnitude, both with respect to performance and ability to engage our workforce (mostly Python programmers).<p>Previous tools that improved workflow: docker, nginx.
ZeroMQ, React, Node.js, Nginx, Redis, PostgreSQL, and of course Linux. Together they make a great platform for building quality apps very quickly (which is the point of our organization).
Kubernetes has been amazing for us. Getting better every month.<p>More recently, Drone for CI has been a quantum leap in usability for us over Jenkins. Built on top of Docker, has service container support built in, and has the unique feature of plugins-as-Docker-containers (so you can write them in any language): <a href="https://github.com/drone/drone" rel="nofollow">https://github.com/drone/drone</a><p>Ansible, ramping up with some Terraform and really loving it.
If you haven't heard of Heka (<a href="http://hekad.rtfd.org" rel="nofollow">http://hekad.rtfd.org</a>), you should check it out.