Open source field service software (FSS) relies on open architecture; that is, it can be modified by anyone with the knowledge and means to do so. Because many kinds of popular open source software, including games, word processors like Openoffice, or the Photoshop alternative GIMP, are free, "open source" is often confused or conflated with free.
Similarly, many people think that because it's open source and may be free or less expensive than its commercial counterparts, you likely get what you pay for. Both of those assumptions can be true in some cases, but they aren't always. Open source field service management software can be less expensive, easier to scale, and surprisingly easy to customize. For businesses with the right intersection of needs and skills, it can prove a viable solution.
Open Source Advantages
Cost: Commercial Field Service Software relies on paid programmers, a company infrastructure, a marketing department, and what often seems like a cast of thousands... each of whom, need to be paid. Those expenses carry over to product cost. Because the process behind open source software is different, costs range from lower to nonexistent.
Creativity: Open source software will, from time to time, include features and solutions that are absent from commercial products just because a programmer thought the idea was worth trying. Corporate software may exclude features for which the parent company feels there is insufficient demand.
Stability: Open source software is often developed by highly-skilled programmers, and the code that underpins it is usually much more stripped-down because it's not being worked on by one or more teams of people (who may have conflicting styles and agendas).
Flexibility: Much open source software is released under the Gnu Public License or a Creative Commons license, making it easier to adapt to businesses with a large number of users without breaking the bank. It can also be modified, allowing you to leave out the bits you don't need, or to change the bits you use most often.
Open Source Disadvantages
Security: Open source security is a decidedly mixed bag -- see the Security and Privacy section below.
User Interface: One advantage to commercial software is that the UI (User Interface) tends to be easy to navigate and use. Open source software tends to prioritize function over UX, leading to an interface that can be cluttered, counterintuitive, or downright confusing.
Lack of Support: Looking for documentation? You may be out of luck. Looking for a customer support hotline? You're almost certainly out of luck. Documentation is typically sparse, and support is more likely to be offered via a user forum than a manual. If someone doesn't see your question, or if you're working off a recently updated version of the software, that can be a problem. And speaking of updates, programmers can stop supporting software at any time, leaving you with a system that may work well for you initially but that eventually may not be compatible with your IT infrastructure or your business needs, with no means of updating or upgrading.
Open Source Field Service Software Features
You can find many of the same features on open source field service solutions that you'd find on their paid alternatives, including customer record management, CRM, Google Maps integration, work order management, scheduling, timesheets, billing and invoicing, and payment processing.
Broadly speaking, open source solutions are well suited to small businesses. When it comes to SMBs using field service software, this translates to home services businesses like landscapers, installers, and other types of field techs.
The open nature of open source software is likely to raise concerns for businesses that need field service software solutions that fit specific regulatory and compliance guidelines that require a higher degree of security (i.e., HIPAA or Sarbanes-Oxley compliance).
Open Source Security and Privacy
Security and privacy can be a double-edged sword with anything that's open source. On one hand, you should be cautious about downloading from anyone except the original vendor, especially if the software is not only open source, but also free. That's because third-party distributors can, and sometimes do, add malware, spyware, or adware to the software before putting it on their servers.
On the other hand, the open nature of the software can also be an asset, since improvements, patches, and plugins can be developed by anyone. Rather than waiting a long time for a bug fix, the community often takes matters into its own hands. And if your IT department is competent, it's easy for them to make modifications and fixes as well.
There are a range of options here, ranging from MyIT CRM's genuinely free offering to fieldomobify's multiple pricing plans. In contrast to traditional offerings (which charge per user/per month), the price structure tends to cover a set number of users for a set monthly price under different service tiers.
There aren't quite as many vendors in the open source field service software space as exist in the traditional segment of the field. A few of the standouts include CalemEAM (which offers a free/light edition of its enterprise software to SMBs), Comma CMMS (free for one user), Field Force Tracker, fieldomobify, Maestro, MyIT CRM, Openbravo, and OpenMaint.
It's worth noting that some of these solutions could be adapted among several industries, but you're unlikely to find the degree of specialization here that you'd find from traditional providers.