HubSpot App Builder (Platform 2025.2)

This skill guides the development of full HubSpot apps on the latest developer platform (version 2025.2), covering project creation, configuration, UI extensions, webhooks, and distribution.

Prerequisites

HubSpot CLI v7.6.0+: npm install -g @hubspot/cli@latest
Authenticate: hs account auth
Node.js 18+
A HubSpot developer account

Project Setup Workflow

1. Create the Project

hs project create

Follow CLI prompts to configure:

Distribution: marketplace (for App Marketplace listing) or private (for specific accounts)
Auth: oauth (multiple accounts) or static (single account)
Features: Select from card, settings, app-function, webhooks, workflow-action

To add a feature later:

hs project add

2. Project File Structure

my-project-folder/
├── hsproject.json
└── src/
    └── app/
        ├── app-hsmeta.json          # Top-level app config (required)
        ├── cards/                    # UI extension cards
        │   ├── MyCard.jsx
        │   ├── my-card-hsmeta.json
        │   └── package.json
        ├── settings/                 # App settings page
        │   ├── Settings.tsx
        │   ├── settings-hsmeta.json
        │   └── package.json
        ├── app-events/               # App events (open beta)
        │   └── my-event-hsmeta.json
        ├── app-objects/              # App objects (open beta)
        │   └── my-object-hsmeta.json
        ├── webhooks/                 # Webhook subscriptions
        │   └── webhooks-hsmeta.json
        └── workflow-actions/         # Custom workflow actions
            └── custom-action-hsmeta.json

3. Configure `app-hsmeta.json`

{
  "uid": "my_app_uid",
  "type": "app",
  "config": {
    "name": "My App",
    "description": "App description for installing users.",
    "distribution": "marketplace",
    "auth": {
      "type": "oauth",
      "redirectUrls": ["http://localhost:3000/oauth-callback"],
      "requiredScopes": ["crm.objects.contacts.read"],
      "optionalScopes": [],
      "conditionallyRequiredScopes": []
    },
    "permittedUrls": {
      "fetch": ["https://api.example.com"],
      "iframe": [],
      "img": []
    },
    "support": {
      "supportEmail": "support@example.com",
      "documentationUrl": "https://example.com/docs"
    }
  }
}

Key rules:

uid must be globally unique within the project (up to 64 chars, alphanumeric + _, -, .)
type must match the parent folder name (app)
Use static auth + remove redirectUrls for single-account private apps
At minimum, include one read scope (e.g., crm.objects.contacts.read)

4. Upload and Deploy

hs project upload          # Upload and trigger a build
hs project open            # Open project in HubSpot browser
hs project dev             # Start local dev server with hot reload
hs project install-deps    # Install package.json dependencies

5. Install the App

After uploading, install via HubSpot UI:

Navigate to Development > Projects > [Project Name] > [App UID]
Click the Distribution tab
For test accounts: click Add test install(s)
For standard accounts: click Install now

UI Extensions

All UI extensions share the same structure: a *-hsmeta.json config + a React component file (.jsx or .tsx).

App Card Configuration (`cards/*-hsmeta.json`)

{
  "uid": "my-card",
  "type": "card",
  "config": {
    "name": "My Card",
    "description": "Card description.",
    "location": "crm.record.tab",
    "entrypoint": "/app/cards/MyCard.jsx",
    "objectTypes": ["contacts"]
  }
}

Supported locations:

Location	Value	Notes
CRM middle column	`crm.record.tab`	Most common; supports custom tabs
CRM right sidebar	`crm.record.sidebar`	No CRM data components here
CRM preview panel	`crm.preview`	Record previews across CRM
Help desk sidebar	`helpdesk.sidebar`	Requires `tickets` scope
App home page	`home`	Full-screen extension
App settings page	`settings`	Config UI in HubSpot settings

Supported objectTypes: contacts, companies, deals, tickets, orders, carts, p_customObjectName, app_object_uid

React Component Pattern

import React from "react";
import { hubspot, Text, Button, Flex } from "@hubspot/ui-extensions";

// Required: register extension with HubSpot
hubspot.extend(({ context, actions }) => (
  <MyCard context={context} addAlert={actions.addAlert} />
));

const MyCard = ({ context, addAlert }) => {
  return (
    <Flex direction="column" gap="medium">
      <Text>Hello, {context.user.firstName}!</Text>
      <Button onClick={() => addAlert({ type: "success", title: "Done", message: "Action completed" })}>
        Click me
      </Button>
    </Flex>
  );
};

SDK Hooks (Preferred Approach)

import { hubspot, Button, useExtensionApi } from "@hubspot/ui-extensions";
import { useCrmProperties } from "@hubspot/ui-extensions/crm";

hubspot.extend<'crm.record.tab'>(() => <MyCard />);

const MyCard = () => {
  // Access both context and actions
  const { context, actions } = useExtensionApi<'crm.record.tab'>();

  // Fetch CRM properties from the current record
  const { properties, isLoading } = useCrmProperties(["firstname", "lastname", "email"]);

  if (isLoading) return <Text>Loading...</Text>;

  return (
    <Button onClick={() => actions.addAlert({ message: `Hello ${properties.firstname}!` })}>
      Say Hello
    </Button>
  );
};

Available hooks:

useExtensionApi<location>() — access both context + actions
useExtensionContext<location>() — access context only
useExtensionActions<location>() — access actions only
useCrmProperties(["prop1", "prop2"]) — from @hubspot/ui-extensions/crm
useAssociations({ toObjectType, properties, pageLength }) — from @hubspot/ui-extensions/crm

Fetching External Data

import { hubspot } from "@hubspot/ui-extensions";

// GET
const response = await hubspot.fetch("https://api.example.com/data", {
  method: "GET",
  timeout: 5000,
});
const data = await response.json();

// POST — body is a plain object, not JSON.stringify()
const response = await hubspot.fetch("https://api.example.com/data", {
  method: "POST",
  body: { key: "value" },
});

Key differences from native fetch:

body is a plain object — do not JSON.stringify() or set Content-Type manually
Only Authorization is supported as a custom header
URLs must be listed in permittedUrls.fetch; localhost is not allowed (use a proxy)
HubSpot appends userId, portalId, userEmail, appId as query params on every request
Max 20 concurrent requests; 15s timeout; 1MB payload limit

Your backend must validate X-HubSpot-Signature-v3 on every incoming request — see references/signature-validation.md.

For the full guide (proxy setup, Authorization header pattern, local dev signing, monitoring), see references/fetching-data.md.

Available UI Components

Import from @hubspot/ui-extensions:

Layout: Flex, Box, Divider, Grid
Text/Display: Text, Heading, Image, Link
Input: Input, TextArea, Select, MultiSelect, Checkbox, RadioButton, DateInput, NumberInput
Actions: Button, LoadingButton, IconButton
Feedback: Alert, LoadingSpinner, Tag, Badge
Overlay: Modal, ModalBody, ModalFooter, Panel, PanelBody, PanelFooter
Data: Table, TableHead, TableBody, TableRow, TableCell
Form: Form, FormField

Import from @hubspot/ui-extensions/crm (CRM points only, not sidebar):

CrmPropertyList — display/edit CRM properties
CrmAssociationTable — show associated records
CrmAssociationPivotTable
ReportChart

Webhooks Configuration

Create src/app/webhooks/webhooks-hsmeta.json:

{
  "uid": "my-webhooks",
  "type": "webhooks",
  "config": {
    "settings": {
      "targetUrl": "https://api.example.com/webhook",
      "maxConcurrentRequests": 10
    },
    "subscriptions": {
      "crmObjects": [
        {
          "subscriptionType": "object.creation",
          "objectType": "contact",
          "active": true
        },
        {
          "subscriptionType": "object.propertyChange",
          "objectType": "contact",
          "active": true
        }
      ],
      "legacyCrmObjects": [
        {
          "subscriptionType": "contact.propertyChange",
          "propertyName": "email",
          "active": true
        }
      ],
      "hubEvents": [
        {
          "subscriptionType": "contact.privacyDeletion",
          "active": true
        }
      ]
    }
  }
}

Use crmObjects for new-format events (object.*). Use legacyCrmObjects for classic types like contact.creation. Use hubEvents for contact.privacyDeletion and conversation.*.

Signature Validation (Required)

HubSpot signs all outbound requests with X-HubSpot-Signature-v3:

Webhook deliveries — HubSpot POSTs event payloads to your targetUrl
Card / settings page fetch — any hubspot.fetch() call from a UI extension is proxied and signed by HubSpot

Both must be validated the same way using Signature.isValid() from @hubspot/api-client. For the complete implementation, see references/signature-validation.md.

`package.json` for UI Extensions

{
  "name": "my-card",
  "version": "0.1.0",
  "dependencies": {
    "@hubspot/ui-extensions": "latest",
    "react": "^18.2.0"
  },
  "devDependencies": {
    "typescript": "^5.3.3"
  }
}

Install: hs project install-deps

Distribution & Auth Summary

Distribution	Auth Type	Install Limit
`private`	`static`	1 standard account + 10 test accounts
`private`	`oauth`	Up to 10 allowlisted accounts
`marketplace`	`oauth`	25 before listing; unlimited after

App Marketplace Listing

Before submitting to the HubSpot App Marketplace, the app must meet these key requirements:

Technical minimums:

OAuth is the sole authorization method — no API keys or private app tokens
At least 3 active installs from unaffiliated accounts with OAuth-authenticated API activity in the past 30 days
Only request scopes the app actually uses; all requested scopes must appear in the Shared data table
Classic CRM cards are not allowed (deprecated June 16, 2025)

Listing content:

Content must be integration-specific (not general product marketing)
All URLs must be live, publicly accessible, and under 250 characters — add HubSpot Crawler to your site allow list before submitting
Include: setup documentation, Install button URL, support resources, Terms of Service, Privacy Policy, and pricing (matching your website exactly)
Bi-directional sync must be declared in Shared data when both read and write scopes are requested for the same object

App cards (if using UI extensions):

Do not use HubSpot brand names in card names or icons
One primary button per surface; destructive buttons must use destructive styling
Must not access or display sensitive data

Review process: Initial review within 10 business days; full cycle up to 60 days. Only one app can be under review at a time.

For the complete requirements checklist, see references/marketplace-listing.md.

Local Development

hs project dev            # Starts dev server with hot reload

After starting, a local development homepage appears in the test account showing active dev sessions. Changes to .jsx/.tsx files reload automatically.

Note (Chrome 142+): Accept the local network access popup from app.hubspot.com on first launch.

Debugging

View logs: Development > Monitoring > Logs > UI Extensions in HubSpot.

In code, use the logger:

import { logger } from "@hubspot/ui-extensions";
logger.info("Info message");
logger.debug("Debug message");
logger.warn("Warning message");
logger.error("Error message");

Additional Resources

Reference Files

For detailed configuration and patterns, consult:

references/app-configuration.md — Complete app-hsmeta.json schema, auth types
references/scopes.md — Full list of available OAuth scopes grouped by category (CRM, CMS, settings, marketing, etc.)
references/ui-extensions-sdk.md — SDK hooks, context fields, actions API
references/fetching-data.md — hubspot.fetch() full guide: differences from native fetch, limits, auto query params, Authorization header pattern, local dev proxy, signature validation
references/ui-components.md — All UI components with examples
references/features.md — App events, app objects (open beta), settings page, home page
references/signature-validation.md — Full signature validation implementation for webhooks and card/settings page fetch endpoints
references/marketplace-listing.md — Full App Marketplace listing requirements, brand rules, app card criteria, and review process