This article is for anyone considering Odoo or already using it, and sets out plainly what the OCA is and why its work matters.
Most business systems, ERP among them, have historically been supplied as proprietary — closed — software. So among those who first came across Odoo while looking for an ERP for a small or mid-sized company, plenty are likely to find the ideas of "open source" and "community" fairly unfamiliar.
Open source means an arrangement in which the inside of the software — the source code — is published, anyone can see what it contains, and under certain conditions it may be improved and redistributed.
Odoo is what is called an open-core ERP: the part that forms the base of the system, roughly 80% of the whole, is published as open source. The source code of Odoo's Community edition is there on GitHub for anyone to read.
Open source and community
Odoo is no exception: every piece of open-source software is held up by the volunteer work of what is called a community. Linux is the example usually given.
In the Linux community it is not unusual for a problem to be solved in a short space of time — a bug found somewhere in the world gets reported, a developer in another region several time zones away fixes it, and someone else again tests it. All of that happens through companies and individuals taking part of their own accord.
For a developer, contributing to the community is how technical ability and a track record get recognised, and how trust and standing inside the community are built.
For a user, bugs keep getting fixed and new features keep arriving, which is what makes it possible to go on using the software with confidence.
A cycle in which the people who use, the people who build and the people who improve raise the value between them — that is the community ecosystem holding open source up.
Odoo's community
Like any other open-source software, Odoo has an active community. What that community does is develop the generally useful functionality that Odoo's standard features do not cover, and fix bugs in versions Odoo S.A. has stopped supporting officially.
The body carrying that role is the OCA (Odoo Community Association).
The OCA was founded in 2013, and developers from all over the world take part, many of them working at Odoo partner companies.
Some readers may wonder at this point: if there is generally useful functionality Odoo lacks, why does Odoo S.A. not build it as a standard feature?
The reason is that Odoo S.A. has put its effort into large advances in functionality with each yearly version, rather than into answering fine-grained individual needs. Its strategy is to release a new version every year and to prioritise the completeness and usability of the system as a whole.
And it is fair to say that Odoo S.A. can pursue that strategy precisely because the OCA community exists.
Odoo S.A. concentrates on advancing the core while the OCA fills in the general functionality the field asks for. That division of labour is one of the big reasons Odoo as an ERP has kept growing.
What the OCA is worth to a company choosing Odoo now
For a company about to choose Odoo as its ERP, whether it understands that the OCA (Odoo Community Association) exists is in fact a very important point.
The most obvious benefit of using OCA modules is that they are free, but there are larger benefits besides. The long-term ones are hard to see, so they are worth spelling out.
An ERP, once implemented, is a system you keep using for ten or twenty years.
That makes it essential to look beyond "the features it has now" and ask whether you can keep using it with confidence into the future.
The reassurance of not depending too heavily on one vendor
With a typical ERP it is common to end up heavily dependent on a particular vendor or development company. Should that company withdraw or change its support policy, the future of the system becomes uncertain.
With Odoo there is the OCA, a community on a global scale, and there:
- many companies and engineers are involved in development and maintenance
- functionality and know-how are shared openly
- the assets accumulate in a form that does not depend on any single company
Those are the points that set it apart.
For a user company that means an ERP where vendor lock-in is easier to avoid.
Modules with a track record, ready to use
The OCA publishes modules developed by Odoo partners around the world. They were built against real operational problems, and they have been used in projects.
Which is to say:
- you do not have to build from zero
- you can make use of designs with a track record
- later modification and extension are easier
Those are the benefits.
Seen from the company's side, that amounts to building an ERP that fits you while holding down development cost and risk.
Strength for long-term operation and upgrades
One of the common complaints in running an ERP is that "upgrading is hard".
Let bespoke customisation pile up too far and future updates become difficult. OCA modules, by contrast,
- are designed against shared rules
- are maintained by the community as a whole
- keep being brought up to date with new versions
Those are their characteristics.
So instead of "build it and you are done", an ERP you can keep growing becomes the realistic outcome.
Choosing a partner who understands the OCA matters
When you choose Odoo, which Odoo partner you work with goes a long way to deciding whether it succeeds.
With a partner who understands the OCA's thinking, and who can develop while giving back to the community where appropriate, there is:
- design with the future in view
- an implementation that is maintainable and extensible
- an ERP built along global standards
All of that you can expect.
The OCA is Odoo's foundation of confidence
The OCA is not a feature you can see, but it is a very important foundation holding up Odoo as an ERP.
For a company choosing Odoo now,
the existence of the OCA
- means you can use it for a long time with confidence
- means you can respond flexibly to change
- means your future options are not narrowed
or so we would put it.
Seeing Odoo not merely as an "ERP product" but as an ecosystem that keeps growing is, we think, the first step towards a successful Odoo implementation.
The state of OCA work in Japan
Odoo partners in Japan are gradually increasing in number, but there are still not many companies actually and continuously involved in developing OCA modules. Quartile is one of the few Japanese companies taking OCA work on in earnest.
The OCA's l10n-japan repository is the official repository for Japanese localisation — accounting, tax and business-practice support — and every module registered there today is one Quartile has developed and maintained.
Lately, though, comments, suggestions for improvement and corrections have started arriving from Japanese Odoo partners and users. Slowly, we feel that OCA work and community development are beginning to be recognised in Japan too.
Awareness of Odoo itself is climbing steadily in Japan at present. What Quartile wants is to work with the other Odoo partners more closely from here, make community work livelier, and build the conditions in which Odoo can be used in Japan with more confidence and more easily.
What modules does the OCA actually have?
So what modules does the OCA actually hold?
The OCA develops and publishes a great deal of generally useful functionality that Odoo's standard features do not cover, along with additional features commonly wanted in a given country or industry.
There is a great deal of it, and someone meeting the OCA for the first time may well feel they cannot tell which to use.
So the blog post below introduces, in plain terms, the OCA modules commonly used when implementing Odoo in Japan.
- Quartile site: The 2025 edition — five Quartile-built OCA modules you cannot do without when implementing Odoo in Japan
The forum on the Quartile site also explains what various OCA modules do and how to use them in practice. It is useful whether you are still considering Odoo or have already started using it, so do have a look.
- Quartile site: Forum posts explaining OCA modules
OCA modules can also be found by keyword search in the OCA app store. Note, though, that the app store does not cover every module and every version that exists on GitHub. If you want to search more broadly, we recommend checking the OCA repositories on GitHub as well.
The difficulties in community work
We have talked about the good side of the OCA so far. To close, we want to touch on the difficulties OCA work carries.
OCA work is done, fundamentally, by volunteers and unpaid.
Saying "let's make use of OCA modules" is easy enough; who bears the cost of actually developing and maintaining that functionality is always the large question.
At Quartile, where a feature we have developed at a customer's request looks generally useful — where we judge it likely to be valuable to other companies too — we propose publishing it as an OCA module.
When we do, the development cost is as a rule borne by the customer who needed the feature first.
As a real example, in the case below we developed the monthly consolidated invoice feature as an OCA module for Japanese localisation.
That case was a relatively large piece of development, but other Quartile customers have understood the point of OCA work, to greater or lesser degrees, and have cooperated in the same way. Let us take this opportunity to thank them again.
At the same time, it is entirely reasonable for someone to feel that "it hardly seems fair that a feature we paid to develop is free for other companies to use".
On that point the difficulty of how to keep cost-sharing fair genuinely exists. Joint development across several companies, and arrangements for sharing cost in future, are both worth exploring — but there is no all-purpose solution as things stand.
Quartile keeps at OCA work all the same, because we think the long-term value outweighs the short-term cost. Concretely: publishing something as an OCA module opens the possibility of other companies improving it and bringing it up to date for new versions, work we may then use for free ourselves. That circulation is particular to a community.
Those benefits, we think, end up serving the customer's own interests.
OCA work is by no means the easy road.
But it is indispensable if Odoo is to grow into an ERP you can use with confidence over a long time. Quartile intends to go on being a partner that does more than implement Odoo — one that keeps giving value back to the Odoo ecosystem itself, together with our customers and the other Odoo partners.
Related links on the OCA:
OCA (Odoo Community Association)
The OCA's development work happens in the following place on GitHub.
For translating OCA modules, a platform called Weblate is used.
What is the OCA (Odoo Community Association)? The role and the benefits to know before implementing Odoo