Open-Source Field Service Management Software: What Is Actually Open?

Two very different questions land on this search. One is “I want software I can host and change.” The other is “I want software I don’t have to pay for.” Open source answers the first properly and the second only sometimes, and almost every roundup on this topic treats them as the same sentence.

The short answer

Open source field service management software is field service software released under a licence that lets you run, read, modify and redistribute the source code, with that code in a public repository you can open right now. Not software that costs nothing. Not software with an API. Not software a directory filed under an “open source” filter. Six projects below meet a licence-and-repository test that we ran on 4 August 2026; two more describe themselves as open source and publish neither, so we say exactly that instead of guessing in either direction.

Who wrote this, and what we are. Opsler makes field service software. Opsler is hosted and is not open source — you cannot download it, self-host it, read its source or fork it. We are not in the table below and we are not eligible for it. A guide to open-source FSM published by a proprietary vendor that failed to mention that would be doing the exact thing this page criticises.

In field service specifically, the licence has to cover the parts of the job that actually matter: work orders, a schedule somebody dispatches from, technicians on phones in basements and crawl spaces, parts coming off a van, and an invoice at the end. Plenty of open-source business software touches two of those five. Rather less covers all of them, and the honest finding of this guide is that the genuine list is shorter than the listicles imply.

For a buyer, an open-source licence buys three specific things. You choose where the software runs, so nobody changes the terms underneath you. Your customer records and job history sit in a database you can query without asking permission. And if the maintainers walk away, the code is still there for somebody else to pick up. Those are real, and they are worth real money to some businesses.

This page is written for the operator or IT lead weighing genuine self-hosted field service software against a hosted product. It is not written for someone whose actual requirement is a bill of zero — that is a different question with a different answer, and it lives on our free FSM comparison. If you are not yet sure which category of software you need at all, start with choosing software for small contractors.

One term to get right before you read any further, because more people trip on it than on anything else here: Odoo field service means two different things depending on which route you take. One is open source. One is a paid, proprietary edition. Section four sets out which is which, with the evidence.

Open Source vs Source Available vs Free SaaS vs Paid SaaS

Four categories, collapsed into one bucket labelled “free or open” by almost every article on this subject. They differ on who holds the code, who runs the servers, who gets woken up, and what happens to you the day the vendor changes its mind. Pick the wrong one and you will not find out for about eight months.

Open source

A recognised open-source licence and a public repository.

You may run it for any purpose, read it, change it and pass the changed version on. You host it, you patch it, you upgrade it. Nobody can take it away from you or reprice it. Examples on this page: Odoo Community, ERPNext, Dolibarr and the OCA field-service modules.

Source available

You can read the code. The licence restricts what you may do next.

Commonly it forbids offering the software as a service, or requires a commercial licence above a revenue or seat threshold. This is a legitimate model and a reasonable thing to buy. It is not open source, and a vendor using the two phrases interchangeably is telling you something.

Free hosted SaaS

Somebody else runs it and charges nothing at this tier.

No source, no right to modify, and terms that can change with notice. What you get instead is that none of the maintenance is yours. Opsler's free plan sits here, along with most of what gets called free field service management software.

Paid hosted SaaS

The same arrangement, with an invoice attached.

What the invoice buys is somebody else owning uptime, backups, patching, upgrades and the pager. Whether that is worth more or less than a licence you control is the actual decision this page is about.

Four things that are not proof of anything

Every one of these gets offered as evidence that a product is open source FSM. None of them is.

A free plan

Free is a price. Open source is a licence. A free tier can be repriced, capped or retired, and it never gave you the right to read or change the code. Opsler's own free plan is in exactly this category.

A public API

An API is permission to talk to software you still cannot see. Useful, sometimes decisive, and completely unrelated to licensing.

Deep configurability, or a low-code builder

Building a custom form, status or workflow is not forking a product. If the vendor switches the feature off next year, a configurable system leaves you with nothing to compile.

A directory's “open source” filter

Those categories are populated from vendor self-description. Several products that appear under them have no public repository at all. The filter is a marketing field, not a licence check.

How We Verified Every Project and Product

Four checks, run against the repository rather than a vendor page, a review site or a directory category. All of them on 4 August 2026. You can repeat any of them yourself in about three minutes per product, and we would rather you did.

1
A public repository exists
Openable by anyone, without an account or an NDA. Two of the products we looked at are marketed as open source and we could not find one at all.
2
The licence, read from the repository itself
Not the badge, not the vendor's About page. Where a repository's reported licence and its own LICENSE file disagree, we show both values rather than choosing. That happened twice, in opposite directions, and both cases are in the table.
3
The date of the most recent activity
An abandoned project with a permissive licence is still abandoned. We record the last push date and the star count as a rough sense of how many other people are depending on it.
4
How much field-service workflow is genuinely present
Whether the project handles work orders, dispatch, technicians and parts, or whether it is a business suite you would have to shape into a field service system yourself. The difference is months of somebody's time.

What we do when a product says it is open source and we cannot confirm it

We write Not stated and describe what we looked for. We do not write “not open source”, because failing to find a licence is not the same as a licence not existing, and a confident denial built on a failed search is worse than no answer. The same rule applies to every capability claim on this site: silence is recorded as silence.

Everything below is a snapshot taken on 4 August 2026. Licences get changed, repositories get archived, and relicensing is common enough in this corner of software that a year-old comparison is worth very little. Re-run the three-minute check before you commit anything to a project.

Comparison Table: Licence, Repository, Maintenance and FSM Coverage

Six projects that publish both a licence and a public repository, ordered by how much field-service workflow they actually contain rather than by how popular they are.

Project	Licence as found	Public repository	Maintenance signal	FSM coverage	Status
OCA Field Service	AGPL-3.0	OCA/field-service	Commits on 3 Aug 2026192 stars	Field service core	Verified open source
Odoo Community	LGPL-3.0	odoo/odoo	Commits on 3 Aug 202653,458 stars	Business suite	Verified open source
ERPNext	GPL-3.0	frappe/erpnext	Commits on 3 Aug 202637,555 stars	Business suite	Verified open source
Dolibarr	GPL-3.0	Dolibarr/dolibarr	Commits on 2 Aug 20267,476 stars	Interventions module	Verified open source
FSM for ERPNext	AGPL-3.0	Beveren-Software-Inc/Field_Service_Management	Last push 19 Jun 202614 stars	Field service core	Verified open source
Open Field Scheduling	MIT in the LICENSE file, AGPL-3.0 in the README	clawnify/open-fieldservice	Last push 22 Jul 202612 stars	Scheduling and dispatch	Unclear

Licence, repository, last push and star count read from each project’s own repository on 4 August 2026. Unclear means the project states two different licences in two different places.

Odoo field service: the distinction almost every roundup flattens

Odoo is dual-licensed, and searching for Odoo field service can land you on either side of that line without the page telling you which one you are looking at.

Odoo Community is genuinely open source. The LICENSE file on branch 19.0 opens with “GNU LESSER GENERAL PUBLIC LICENSE, Version 3”, and Odoo’s own licensing documentation confirms LGPLv3 for the Community edition.
Odoo Enterprise is proprietary and paid. The same documentation names the Odoo Enterprise Edition License v1.0 and restricts use to organisations holding a valid, correctly sized Odoo Enterprise subscription.
Odoo’s own Field Service app is not in the Community source tree. We checked directly: at branch 19.0 the odoo/odoo repository lists around 300 add-on directories and not one of them is industry_fsm, the technical name of that app. Requesting the path returns a 404.

There is a second trap layered on the first. Odoo’s Field Service product page offers the app “free, forever, with unlimited users” on the basis that your first Odoo app is always free. That is a hosted single-app plan on Odoo’s own cloud. It is a free SaaS tier, not the LGPL edition, and taking it does not put you in possession of anything you can self-host or modify. Free and open, one more time, quietly swapped.

So the open-source route to Odoo field service is specific and it is real: Odoo Community, plus the OCA field-service modules, both verified above. If somebody tells you Odoo field service is open source and stops there, they have flattened a distinction that decides whether you can legally run the thing you think you are evaluating.

Marketed as open source, licence and repository not stated

Both of these describe themselves as open source in their own words. Neither published a licence or a repository we could locate on 4 August 2026. That is recorded as what it is — a gap in the evidence, not a verdict.

Open FSM

Open Source Integrators Not stated

The product page describes open-source field service and business applications and names Odoo as the platform underneath. It does not name a repository for Open FSM itself, and it does not state a licence for it.

Worth saying clearly: Open Source Integrators publishes ursais/field-service, a public fork of the OCA field-service modules, with commits on 1 Aug 2026. The open-source work is real. What we could not find is a licence or repository for the branded Open FSM offering, which is a different question.

MIT in the LICENSE file, AGPL-3.0 in the README Unclear

clawnify/open-fieldservice

A standalone, self-hosted scheduling and dispatch application aimed at pest control, HVAC, plumbing, cleaning and landscaping, with job scheduling, technician workload, a weekly calendar and job-status workflow. Created in April 2026, which makes it the youngest thing on this page by a wide margin.

Best for

Reading, if you want a small codebase you could actually finish reading before adopting.

Watch out for

Four months old, twelve stars, and its own two licence statements disagree. Resolve that with the maintainer in writing before it touches customer data.

Licence evidence: The repository's LICENSE file is the MIT text. Its README states AGPL-3.0. Those are very different obligations, and we are not going to pick one on the project's behalf. Last push 22 Jul 2026, 12 stars, checked 4 August 2026.

The pattern worth noticing. The projects with the deepest field-service coverage have the smallest communities, and the projects with the largest communities are business suites you have to build a field service system inside. There is no open-source equivalent of a mature, single-purpose FSM product with tens of thousands of users behind it. That is the honest state of open source FSM as of 4 August 2026, and it is the fact most of the roundups are working around when they pad the list with hosted SaaS.

Hosted Free Plans, and Why They Are Not Open Source

A good share of the people searching for open-source FSM have no ideological requirement at all. They have three vans, a quote from a vendor that wants five seats when they need two, and a suspicion that the price only ever goes one way. That is a real problem. Open source is one answer to it and usually not the cheapest one.

Hosted free field service management software answers the same problem from the other end: a vendor runs the servers, patches the software and eats the maintenance, and charges you nothing inside a published set of limits. You get none of the four freedoms and none of the four-in-the-morning phone calls. Whether that is a good trade depends entirely on whether the limits fit your job volume.

Which vendors publish a genuinely permanent free plan, what the seat and job caps actually are, and which “free” offers are trials with a countdown on them, is a separate piece of work with its own dated figures read from each vendor’s own pricing page. It is on our free FSM comparison, and deliberately not repeated here.

The one point that belongs on this page rather than that one

A free plan is a price. An open-source licence is a right. The price can be changed, capped, grandfathered or withdrawn, and none of that requires your agreement. The right cannot be taken back from the copy you already hold.

Which means the question to ask yourself before shortlisting anything is not “which of these is free?” but “if this vendor doubled its price or shut down in eighteen months, what would I do on the Monday?” If the honest answer is “export and move”, a hosted plan is fine and you should go and test the export. If the honest answer is “we would be finished”, that is what an open-source licence is for.

Security, Updates, Backups and Implementation Burden

The licence is free. The system is not. Every one of these lines exists the day you go live and every one of them recurs, and we are not going to invent dollar figures for your infrastructure or your hourly rate. Price them yourself. The last line is the one that decides the outcome.

The server, and everything under it

Provisioned, sized, patched and monitored. This is the cheapest line on the list and the one every $0-versus-subscription comparison stops at.

Backups you have actually restored

An untested backup is a belief. Restore one onto a scratch instance and confirm the job history is really in it, on a day when nothing is on fire.

Certificates, domains and mail delivery

Mostly automatable, all still yours. An expired certificate takes every technician offline at the same moment, usually first thing on a Monday.

Version upgrades

The line that bites. Platform releases keep moving, community modules follow at their own pace, and anything you customised has to be carried across each time.

Security patching, on your clock

With hosted software somebody else watches the advisories. Self-hosted, you subscribe to them, and the window between disclosure and your patch is a window you own.

A named person who owns all of the above

The real cost, and the one that decides it. Systems maintained by whoever has time are maintained brilliantly for one quarter and then not at all.

There is a second cost that never appears on anyone’s list, and it is the implementation. None of the suite platforms above arrives configured for a service business. Somebody has to model your job types, your price book, your tax handling, your technician roles and your invoice flow, then test all of it against how your office actually works. On Odoo or ERPNext that is weeks of work by someone who knows the platform, and paying a partner to do it is a normal and sensible expense that belongs in the comparison.

The comparison people run in their heads is “$0 against a subscription”. The comparison that survives contact with the second year is “a subscription against a server bill, plus implementation, plus however many hours a month this takes, valued at what your time is actually worth”. For a firm with genuine in-house technical capacity that arithmetic can land comfortably on the self-hosted side. For a six-person plumbing company where the owner is also the only person who has ever used SSH, it usually does not, and the failure mode is not a surprise invoice. It is a system nobody has patched since spring.

When Self-Hosting Makes Sense — and When It Does Not

Written for the size of business this site is for: roughly two to twenty technicians. Above that the calculation changes, because a company with fifty vans generally has somebody whose job is systems, and per-seat pricing at that headcount is a number worth engineering around.

Self-hosting is the right call when

Somebody's job description already includes servers and backups — not somebody technical who is willing to help out.
A contract, a client or a regulator requires the data to live somewhere specific.
You need to change how the workflow behaves, past what any product's settings expose.
You are big enough that per-seat pricing genuinely outweighs several hours a month of maintenance.
You want the software to outlive whichever vendor currently sells it.

It is the wrong call when

Nobody in the business would notice a failed backup until somebody asked for last March's invoice.
Your technicians need a working phone app in week one. Mobile is consistently the thinnest part of a self-hosted stack.
The decision is being made on licence price with the hours left uncosted.
You would be the only person who could fix it, and you also quote, dispatch and chase the money.
What you actually want is to stop paying for seats you do not use. That is a pricing problem and it has a pricing answer.

A concrete version of the same decision. Take a twelve-technician commercial refrigeration company with an office manager, a part-time bookkeeper and a contract with a supermarket chain that specifies where service data may be stored. That firm has a genuine reason to control its own hosting, enough seats for the licence saving to matter, and enough revenue to pay somebody to own the system. Odoo Community with the OCA field-service modules is a defensible choice for them, and they should budget for a partner.

Now take a four-person plumbing firm where the owner still runs jobs three days a week. Same licence, same modules, and the outcome is different: the install goes well, the first upgrade gets postponed because July is busy, and eighteen months later they are running an unpatched instance that only one person understands and that person is on a roof. The software was never the problem. The maintenance was, and it was predictable from the start.

One practical note for either path: the technician’s phone is where self-hosted stacks most often disappoint, because signal drops in plant rooms, basements and rural properties and mobile is the least-finished part of most open-source suites. Whatever you shortlist, test it in a basement before you commit. What a technician can and cannot do without a signal sets out how we handle that end of it, so you have something to compare against.

Where Opsler Fits as Hosted Software

Opsler is hosted software and it is not open source. We run it, you subscribe to it, and the source is not published. You cannot download it, install it on your own server, read it or fork it. If any of those is a requirement, stop here and use the table above — that is what it is for, and we would rather send you to the right category than sell you the wrong one.

What we can speak to is the requirement that sometimes sits underneath the requirement. Licence freedom is occasionally the real driver. Often enough it is cost, a seat minimum, or a fear of being locked in wearing licence language, and each of those three has an answer that does not involve standing up a server.

Cost

Our free Budding plan has no time limit and no card: 2 seats — 1 admin and 1 technician — with 50 jobs a month, unlimited customers, and 100 inventory items in 1 inventory location.

Seat minimums

Pro is $25 per seat per month with no seat minimum. Three people pay for three seats. There is also a 14-day trial with no credit card, and a one-time $499 lifetime option covering 5 seats.

Lock-in

Customer records and a generic accounting CSV export are available on the free plan. QuickBooks-formatted and Xero-formatted exports are a Pro feature. Each produces a file you import manually — none of them is a live accounting connection.

Being able to export is not the same as owning the software, and we are not going to blur those two the way this whole category tends to. If the vendor disappears, an export gets you your data and not your system. An open-source licence gets you both. That is a real difference and it is worth what it is worth to you, which is a question only you can price.

So here is a reasonable way to close the decision. If control of the software is genuinely the requirement, self-host, pick from the verified list, and budget for the maintenance honestly rather than optimistically. If the requirement is really that you refuse to pay for four seats when you have two, that is a pricing problem, and a hosted product without a seat minimum solves it without anybody learning to administer a database.

Compare Opsler’s hosted free plan See the free FSM comparison

Residual FAQs

The questions this guide gets asked that the sections above do not already answer in full.

Neither. Opsler is hosted software: we run it, you subscribe to it, and the source is not published. You cannot download it, install it on your own server, read it or fork it. We do have a permanently free plan, but a free plan is a price and not a licence, which is the distinction this entire guide exists to draw. If owning or modifying the code is a genuine requirement rather than a preference, the verified table above is the useful part of this page and Opsler is not on it.

Checked on 4 August 2026 against each project's own repository: OCA Field Service (AGPL-3.0), Odoo Community (LGPL-3.0 in its LICENSE file), ERPNext (GPL-3.0), Dolibarr (GPL-3.0) and FSM for ERPNext (AGPL-3.0) all publish a licence and a public repository. Open Field Scheduling publishes both as well, but its LICENSE file says MIT while its README says AGPL-3.0, so we list it as unclear rather than pick one. For a real field-service workflow under a recognised open-source licence, Odoo Community plus the OCA field-service modules is the strongest combination we could verify.

Running AGPL software inside your own company to dispatch your own technicians is the ordinary use of it, and it carries no obligation to publish anything. The clause people have heard about is triggered by offering modified software to other people over a network. If your plan is to modify an open-source FSM system and sell access to it, take legal advice on your specific plan. If your plan is to schedule your own vans with it, this is not something you need to think about. Nothing here is legal advice.

Ask about the exit before you ask about the features, in both directions. Self-hosted, the database is yours, which is only useful if you know how to get a clean export out of it and have tried. Hosted, ask what leaves and in what format. On Opsler, customer records and a generic accounting CSV export are available on the free plan; the QuickBooks-formatted and Xero-formatted versions of that export are a Pro feature. All of them produce a file you import manually. None of them is a live accounting connection, and we do not describe it as one.

Because they are assembled from software-directory data, and those directories fill their open-source category from what vendors write about themselves. A product with an API, a free tier or a plugin marketplace routinely ends up tagged that way, and the tag then gets copied into the next article. The check takes about three minutes per product: find the public repository, open the LICENSE file, look at the date of the most recent commit. If any one of those three is missing, you have not confirmed anything, whatever the listing says.

Keep Reading

Free FSM plans compared

Which free tiers are permanent, with dated vendor limits

Software for small contractors

Field service, construction PM, takeoff or accounting

Offline technician app

The part self-hosted stacks most often get wrong

Opsler pricing

Free Budding plan, and no seat minimum on Pro

Licences, repositories and maintenance dates checked 4 August 2026 against each project’s own repository. Projects relicense and get archived without announcement — re-check before you commit.

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