Odoo ships with more than 30 native apps and thousands of additional modules in its App Store, so the first question for any small business getting started isn't "what does Odoo do" but "what do I install first". The short answer: a core of four modules covering sales, invoicing, stock and lead capture, and from there, specific modules that get added once the business genuinely needs them — not before.
Key point: you don't need to activate Odoo's whole catalog on day one. Most small businesses start with 4 base modules and add specialized ones as they grow or their business model changes.
The 4 base modules almost every small business activates
These four modules form the operational backbone of any company that sells a product or a service, whether or not it holds physical stock:
Sales
Quotes, sales orders, product catalog and commercial terms, with invoicing built into the same flow. It's the first module almost any small business activates because it structures the whole commercial process end to end, from sending a quote to collecting the invoice.
Accounting / Invoicing
Chart of accounts, bank reconciliation, sales and purchase invoices, and financial reports. In Spain it's also the entry point into e-invoicing obligations that already affect a growing number of small businesses; for the full detail, see our guide to e-invoicing and VeriFactu.
Inventory
Stock management, locations, lot/serial number traceability, and delivery and receipt orders. Essential for any small business moving physical product; if the business is purely service-based, this module becomes optional.
CRM
Opportunity pipeline, lead tracking and sales activities. It's the module that connects marketing and sales before an order even exists, and is usually the second one activated right after Sales whenever there's a sales team.
Table: base modules vs. modules added based on the business
With the four base modules covered, this table sums up the rest of a small business's typical Odoo catalog: what each module does, whether every company needs it or only some, and when it makes sense to activate it.
| Module | Function | Does every business need it? | When to add it |
|---|---|---|---|
| Sales | Quotes, orders and built-in invoicing | Yes, almost always | From day one |
| CRM | Sales pipeline and lead tracking | Yes, if there's a sales team | From day one or shortly after |
| Accounting / Invoicing | Chart of accounts, reconciliation, financial reports | Yes | From day one |
| Inventory | Stock, locations, traceability | Only if there's physical product | From day one if you sell product |
| Purchase | Vendor orders and cost control | Not always | When you manage several vendors |
| Point of Sale (POS) | In-person sales in-store or at events | No | If you have a physical store or sell at events |
| Manufacturing (MRP) | Production orders and bills of materials | No | If you manufacture or assemble product |
| Marketplace connectors | Sync orders and stock with Amazon, Shopify, etc. | No | When you start selling on online marketplaces |
| Compliance / E-invoicing | VeriFactu and country-specific e-invoicing formats | Not universal, increasingly common in Spain | When regulation requires it or you want to get ahead |
| HR | Hiring, payroll, time off, evaluations | No | When the team grows beyond the founder |
| E-signature | Sign contracts and documents paper-free | No | When you handle a lot of documents with customers or vendors |
When to add specialized modules
You sell online on marketplaces
Once the business starts selling on Amazon, Shopify or other marketplaces, updating orders and stock by hand inside Odoo stops being viable very quickly. That's when a marketplace connector automatically syncs orders, stock and invoicing between the sales channel and Odoo. You can browse the connectors available in our catalog of Odoo 19 modules.
You need e-invoicing or VeriFactu
In Spain, e-invoicing obligations and certified invoicing systems such as VeriFactu already affect a growing number of small businesses. The native Accounting module covers a traditional invoice, but complying with a certified invoicing system requires a specific compliance module integrated into Odoo. Read the full detail in our guide to e-invoicing and VeriFactu in Odoo.
The team grows
While the company is just the founder plus one or two people, managing HR in a spreadsheet works reasonably well. Once you outgrow that scale, Odoo's HR modules cover hiring, payroll, time off and evaluations without leaving the same system where sales and accounting already live.
You sign a lot of documents
Contracts with clients, supplier agreements, internal paperwork. Once signing over email becomes routine, an e-signature module integrated into Odoo skips the back-and-forth of attachments and keeps every signed document tracked on the same customer or supplier record.
Your business runs on services, not products
If the small business doesn't sell physical product but instead bills hours, projects or on-site visits, the Inventory module stops being a priority and the Services and Project modules take over instead: work orders, time tracking, and billing by milestone or by usage.
How to choose without overloading Odoo from day one
Don't turn on the whole catalog at once: every active module adds menus, fields and processes the team has to learn and maintain. A rule of thumb that works well: if a native module already covers 80% of what you need, try adjusting it with standard configuration first. If that last 20% is missing — a field, a view, a specific report — before looking for a third-party module or commissioning custom development, customizing Odoo with Odoo Studio is usually the fastest, cheapest route.
Useful links within FlexigoTech
Frequently asked questions
What are the minimum modules to get started with Odoo in a small business?
Sales, Accounting/Invoicing, Inventory and CRM. These four cover the whole commercial process, from the first contact with a customer through to the invoice, and are the base almost every small business builds the rest of its Odoo on.
Do I need the Inventory module if I only sell services, not products?
It's not essential. If your small business bills hours, projects or on-site visits without moving physical stock, the Inventory module becomes optional and it's worth prioritizing the Services or Project modules instead.
When does it make sense to add a marketplace connector in Odoo?
Once you start selling on channels like Amazon, Shopify or other marketplaces and managing orders and stock by hand stops being viable. At that point, a connector automatically syncs orders, stock and invoicing between the marketplace and Odoo.
Can I install as many modules as I want at no extra cost on Odoo Community?
Odoo Community's native modules are free and can be installed with no license cost. Third-party proprietary modules — marketplaces, compliance, advanced HR, e-signature and so on — have a separate cost, usually a one-off license or a subscription, whether you're running Community or Enterprise.
What's the difference between activating a native Odoo module and hiring Odoo Studio customization?
Activating a native module adds functionality already built by Odoo or a third party, as-is. Odoo Studio, on the other hand, doesn't add a new module: it lets you modify fields, views, reports and automations on the modules you already have, with no coding, to fit your specific process.
Not sure where to start with your Odoo modules?
We'll help you decide which modules to activate first based on your type of business, and which ones can wait. Write to comercial@flexigobe.com or call +34 616 809 504.