COM add-ins vs JavaScript add-ins

Draftable Legal reaches into Microsoft Office and Outlook through add-ins, and there are currently two generations of them:

• The COM add-ins (also called VSTO add-ins) — the original integration, installed onto each Windows machine by the Draftable Legal desktop application itself.
• The JavaScript add-ins — the modern integration, deployed centrally to your Microsoft 365 tenant and delivered to users by Microsoft.

Both put a Draftable entry point in front of your users, but they are built, deployed, updated and controlled in completely different ways. If you are deciding which to roll out — or you have inherited an estate running both — this article explains the difference.

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The COM (VSTO) add-ins

These are Windows-only add-ins built on Microsoft’s Visual Studio Tools for Office (VSTO) runtime. There are three: How they behave:

• They are installed by the desktop application, not by you. When Draftable Legal launches, it checks whether each add-in is enabled and installs it for the current user if it is missing. There is no separate installer to deploy.
• They are per user. The add-in is registered under the signed-in user’s profile on that machine, so a user who moves to a new machine gets the add-ins installed again on first launch there.
• They depend on the VSTO runtime being present on the machine. Where it is missing, installation fails and Draftable reports it.
• The comparison always runs in the desktop application. The ribbon button hands your document off to Draftable Legal and the New Comparison window opens.
• They are controlled through the registry and Group Policy under the Draftable Feature namespace. See Most common Draftable Legal registry configurations for the exact values.

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The JavaScript add-ins

These are standard Microsoft 365 Office Add-ins, described by a manifest that you deploy once to your tenant through Integrated apps in the Microsoft 365 admin center. Microsoft then delivers the add-in to the users or groups you nominated. There are five, and they split into two families:

• Draftable in Office / Outlook — a full side panel that runs the comparison workflow inside Word, Excel, PowerPoint or Outlook, including file selection from your DMS, profile selection, comparison type selection and next actions.
• Draftable for Office / Outlook — lighter commands that send the document, attachment, selection or text out to the Draftable Legal desktop application, where the comparison runs with full access to advanced features.

Plus Redline in Email, the Outlook add-in that opens an email in a tracked-changes editor so you can redline the email text itself, accept or reject changes, and send the result as your reply. How they behave:

• You deploy them once, centrally. One manifest URL per add-in, entered in the Microsoft 365 admin center, targeted at everyone or at specific users and groups.
• You choose how binding the deployment is — Fixed (users cannot remove it), Available (users opt in) or Optional (installed but removable).
• Updates can arrive without touching the endpoint. Redline in Email and the Draftable Clean Outlook add-in are served from a latest manifest URL, so new versions within the same major version reach users without a desktop upgrade or a new package. Draftable in Office, Draftable for Office, Draftable in Outlook and Draftable for Outlook are deployed from pinned version URLs, so an administrator deploys a new manifest URL for each update. A new major version can also need a newer desktop application: Redline in Email 3.0 needs Draftable Legal 26.9.0.1 or later and a new manifest URL. See Configuring Redline in Email.
• They still require Draftable Legal on the machine. Each add-in has a minimum desktop version, listed in its installation article above. The for add-ins hand work to the desktop application by design; the in add-ins need it present as well.
• Endpoints must be able to reach dl.draftable.com. If your web filter or proxy blocks it, manifest validation fails at deployment time and the add-ins will not load for users.

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Side by side

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Which should you use?

Deploy the JavaScript add-ins if you can. They cover more host applications, offer richer workflows including in-panel comparison and DMS version selection, deploy and update centrally, and are where the product is going. They also have far less to go wrong on the endpoint: there is no per-user installation step and no VSTO runtime dependency, which is what makes them markedly more reliable across the environments we most often work in. You can deploy them if you have all three of the following:

• A Microsoft 365 tenant, with Global Administrator rights or equivalent permission to use Integrated apps in the Microsoft 365 admin center.
• Endpoints that can reach dl.draftable.com.
• A Draftable Legal desktop version at or above the minimum stated in each add-in’s installation article.

Stay on the COM add-ins where Microsoft 365 Centralized Deployment is not available to you — for example if you are running a non-Microsoft-365 Office licence, or your tenant administration sits outside your team’s control. Running both at once works, but users pay for it. Word and Outlook will show two separate Draftable entry points in the ribbon, with different capabilities behind each, and there is no visual cue as to which is which. In practice this generates support calls. Where you have both, pick one and retire the other.

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Related articles

• Working with our add-ins — what each add-in does, from a user’s point of view
• Moving from the COM add-ins to the JavaScript add-ins
• Draftable Legal Outlook add-in — using the Outlook COM add-in
• Most common Draftable Legal registry configurations