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The Add-ons SDK lets you build your own add-on: new pages that open inside the app, in the left menu, with the signed-in user’s session. PDF Generator is built with it. An add-on is a small React app. You build it into one JavaScript file and upload that file in Settings › Add-ons. There is nothing to host and no server to run.
Uploading a new add-on is open to organizations that build add-ons (an allowlisted group). Ask MileApp to enable it for your organization. Anyone can follow this guide and run an add-on locally before then.

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What an add-on can do

  • Add one or more pages to the left menu, nested under one entry.
  • Read and write your organization’s data through the app’s API: tasks, flows, users, hubs, data sources and more.
  • Check the signed-in user’s permissions, language and light or dark theme.
  • Save its own settings for your organization, which are kept when you upload a new version.
  • Create its own permissions, one per page, so you choose which roles open which page.
  • Bundle any JavaScript library it needs, such as a PDF or spreadsheet library.

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What it cannot do

  • Call a server outside the app directly from the browser. The app’s security policy blocks it. To reach your own system, use a webhook automation: the app calls your server, not the browser.
  • Run on the field mobile app. Add-ons are for the web app.
  • Keep older versions. Uploading a new file replaces the old one.

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How it works

1

Get the SDK

Clone the SDK repository and start a branch for your add-on.
2

Build your pages

Register your pages and build them with the app’s own components. A local preview shows them against your real data.
3

Build one file

One command checks your code and produces a single .js file.
4

Upload and publish

Upload the file in Settings › Add-ons, publish it, and add it to your organization.

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Build it with Claude Code

You do not need to be a developer. Claude Code can run every command and write the code with you. Open the SDK in Claude Code and it connects the MileApp knowledge base and loads the add-on builder skill by itself, so it follows MileApp’s own reference and rules for add-ons. See Build with Claude Code to set it up in two minutes.

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In this section

Build with Claude Code

Open the SDK in Claude Code and let it guide you.

Getting started

Set up the SDK and see your first page.

Building an add-on

Pages, data, settings, permissions and the rules to follow.

Publishing an add-on

Build, upload, publish, update and troubleshoot.