Quick answer: SharePoint Online is delivered as SaaS: Microsoft runs the servers, patches the software and guarantees uptime, and you use it through a browser. The PaaS-style side of SharePoint is what you build on top of it: custom web parts with the SharePoint Framework (SPFx), or API-only document storage with SharePoint Embedded. If you also run SharePoint Server yourself, that is a third model, self-managed software. So the real question is not “PaaS or SaaS?” but “how much do we need to customise, and how much do we want to manage?”
What the SharePoint PaaS SaaS question really means
Most people searching for “SharePoint PaaS SaaS” are trying to decide one of three things: whether to buy SharePoint as a ready-made service, whether to develop custom applications on it, or whether to keep running it on their own servers. Each answer carries a different cost, risk and staffing profile.
The older explanations of this topic describe the cloud stack well, but they stop at definitions. They predate several major changes: SharePoint Add-ins were retired, SharePoint Server 2016 and 2019 lost support, and Microsoft released an API-only product called SharePoint Embedded. This guide updates the picture and gives you numbers you can plan around.
The cloud stack in one table
Cloud services are layered. The higher you go, the less you manage and the less you can change.
| Layer | What the provider runs | What you manage | SharePoint example |
|---|---|---|---|
| IaaS (Infrastructure) | Servers, storage, networking | OS, database, SharePoint install, patches, backups | SharePoint Server farm on virtual machines |
| PaaS (Platform) | Infrastructure plus runtime and tooling | Your application code and data | Custom solutions built with SPFx or SharePoint Embedded |
| SaaS (Software) | Everything, including the application | Users, permissions, content, configuration | SharePoint Online in Microsoft 365 |
A useful way to remember it: IaaS gives you the road, PaaS gives you the vehicle, and SaaS delivers the finished goods. SharePoint can show up at more than one layer, which is exactly why the question causes confusion.
Is SharePoint SaaS or PaaS?
SharePoint Online is SaaS. You subscribe, Microsoft operates it, and updates arrive automatically. Microsoft does not market SharePoint Online as a PaaS product. What gets called “SharePoint PaaS” in practice is the extensibility layer: you write code that runs inside or alongside the service, and Microsoft’s platform hosts the result.
That extensibility layer has changed a lot recently:
- SharePoint Framework (SPFx) is now the standard way to extend SharePoint Online, Teams and Viva Connections with custom code. It is a client-side, JavaScript and TypeScript model.
- SharePoint Add-ins are gone from Microsoft 365. They were retired on April 2, 2026, together with Azure Access Control Services (ACS) authentication, so any add-in that depended on ACS stopped working. SharePoint Add-ins deployed from an on-premises app catalog are not retired by that decision.
- SharePoint Embedded is an API-only file and document platform built on Microsoft 365 and accessed through Microsoft Graph. It has no user interface of its own, so your application supplies one. Microsoft released it in May 2024.
If your team is still maintaining Add-in based customisations, treat them as a migration project, not a future task.
SharePoint as SaaS: what you actually get
For most organisations this is the right default. You get document libraries, team and communication sites, search, permissions and Microsoft 365 integration without running any infrastructure.
| Item | Current figure | Why it matters |
|---|---|---|
| Tenant storage | 1 TB per organisation plus 10 GB per licensed user | Storage is pooled across all sites, not allotted per team |
| Extra storage | About $0.20 per GB per month (about $2,400 per TB per year) | One extra terabyte costs roughly $200 a month |
| Maximum per site | 25 TB | A technical ceiling for any single site |
| Maximum file upload | 250 GB per file | Relevant for media and engineering files |
| Uptime commitment | 99.9% monthly, with 25, 50 and 100 percent service-credit tiers | Credits apply per service and are claimed by the customer |
| Standalone pricing | Plan 1 about $5 and Plan 2 about $10 per user per month, annual commitment | Most organisations buy SharePoint inside a Microsoft 365 bundle instead |
Two practical notes. First, one 2026 pricing review reports that standalone SharePoint Online Plan 1 and Plan 2 are being retired, with sales ending during 2026 and service ending in 2029. We could only find that in a single source, so confirm it in your Microsoft 365 admin center or with your licensing partner before budgeting. Second, the 99.9% figure is a contractual threshold, not a promise of zero downtime. Industry tracking of Microsoft 365 reported about 99.5% overall uptime for the first quarter of 2026, which shows why you should read the SLA terms and plan for occasional disruption.
A worked storage example
The storage formula catches many teams out because it counts only licensed users who contribute storage, and some plans (such as frontline plans) add none.
| Tenant | Calculation | Pooled storage |
|---|---|---|
| 100 users | 1 TB + (100 x 10 GB) | 2 TB |
| 500 users | 1 TB + (500 x 10 GB) | 6 TB |
| 5,000 users | 1 TB + (5,000 x 10 GB) | 51 TB |
If you migrate a large file share into SharePoint Online, check the pooled total first. Overage is billed monthly and grows quickly.
SharePoint as PaaS: when building on top makes sense
Choose the PaaS-style path when the out-of-the-box features do not match a business process, and you have developers to maintain the result.
Use SPFx when you want custom web parts, field renderers or extensions that appear inside SharePoint pages, Teams tabs or Viva Connections. It runs in the user’s browser under their permissions, and Microsoft recommends it as the model for SharePoint extensibility.
Use SharePoint Embedded when you are building a separate application, such as a client portal or an industry app, and want Microsoft 365 document features behind it: Office co-authoring, Purview compliance controls and Copilot access. Its content sits in a dedicated partition of the customer’s tenant, does not count against normal Microsoft 365 storage, and is billed separately through an Azure subscription on a pay-as-you-go basis driven by storage and API usage.
Be careful with custom code that reaches into SharePoint through retired or deprecated methods. Every custom component is something your team must test when Microsoft changes the service, and the service changes continuously.
The third model: self-managed SharePoint Server
Some organisations must stay on their own servers for regulatory, data-residency or network reasons. Support dates now shape that decision.
| Version | Mainstream support ended | Extended support ended | Status |
|---|---|---|---|
| SharePoint Server 2016 | July 13, 2021 | July 14, 2026 | Unsupported, no security updates |
| SharePoint Server 2019 | January 9, 2024 | July 14, 2026 | Unsupported, no security updates |
| SharePoint Server Subscription Edition | Not applicable | Modern Lifecycle Policy | Supported, continuous updates |
The servers did not stop working on July 14, 2026, but newly discovered vulnerabilities in 2016 and 2019 will not be patched by Microsoft. Subscription Edition is the supported on-premises option. It requires Windows Server 2019 or later and SQL Server 2019 or later, and it is licensed with the server and client access licence model rather than a simple per-user online subscription. Direct upgrades are supported from 2016 and 2019 but not from older versions, so a 2013 farm needs an intermediate step. Also note that InfoPath Forms Services support ended on the same July 14, 2026 date.
SaaS vs PaaS-style vs self-managed: side-by-side
| Factor | SharePoint Online (SaaS) | Custom build (SPFx or Embedded) | SharePoint Server SE (self-managed) |
|---|---|---|---|
| Who runs the platform | Microsoft | Microsoft runs the platform; you own your code | You |
| Setup effort | Low | Medium to high | High |
| Customisation | Configuration and no-code tools | High | High, but older customisation models carry risk |
| Patching | Automatic | Automatic platform, your code is yours | You schedule and apply |
| Cost pattern | Per user per month | Per user plus developer time; Embedded adds Azure usage billing | Servers, SQL, licences, staff |
| Best for | Collaboration, intranets, document management | Unique processes and customer-facing apps | Strict data-control requirements |
| Main risk | Vendor-controlled change and storage overage | Maintenance burden | Security and upkeep falling behind |
How to decide: a short framework
- Start with SaaS. If sites, libraries, search and Teams integration cover the need, stop there. Less code means less to maintain.
- Add SPFx only for a gap you can name. Write down the specific process the standard features cannot handle, and who will own the code in two years.
- Choose SharePoint Embedded for a separate application. It suits software products and portals more than internal team sites.
- Choose Subscription Edition only for a documented constraint. A regulation, a network limit or a data-residency rule counts. Habit does not.
- Audit what you already run. List every farm, add-in, InfoPath form and workflow before you decide.
Common mistakes to avoid
- Assuming “SaaS” means no administration. You still own permissions, retention, external sharing and content hygiene.
- Planning storage from user count alone without checking which licences contribute capacity.
- Leaving 2016 or 2019 farms in place because they still run.
- Building new work on Add-ins or other retired models.
- Treating a vendor’s price list as final; confirm current figures with Microsoft or a licensing partner.
Frequently asked questions
Is SharePoint a SaaS or PaaS product?
SharePoint Online is SaaS. Developers can build on it using SPFx or SharePoint Embedded, which is the PaaS-style use. SharePoint Server on your own or rented virtual machines is self-managed software.
Can I use SharePoint as both SaaS and PaaS?
Yes. Many organisations use SharePoint Online as ready-made SaaS and add a few custom SPFx components for gaps. That combination is common and sensible.
What happened to SharePoint Add-ins?
Microsoft retired them in Microsoft 365 on April 2, 2026. SPFx is the supported replacement.
Is SharePoint 2019 still supported?
No. Extended support for SharePoint Server 2016 and 2019 ended on July 14, 2026. SharePoint Server Subscription Edition is the supported on-premises version.
How much storage does SharePoint Online include?
1 TB per organisation plus 10 GB per licensed user, with extra storage at about $0.20 per GB per month.
