Extending the
HubSpot Platform.

How HubSpot connects systems and supports custom experiences to streamline and unify business processes

Presented by Kye Bessant

November 2026

Section 01

Connecting with HubSpot

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling
01
No code

Standard processes and common integrations

Examples

Marketplace appsData SyncData StudioFile imports/exports
No code
HubSpotConnecting with HubSpot
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02
Low code

Custom automation and event-driven workflows

Examples

WorkflowsCustom-code actionsWebhook actions and triggers
Low code
HubSpotConnecting with HubSpot
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03
Full code

Bespoke experiences and deeper control

Examples

HubSpot AppsCustom integrationsUI extensionsCustom quote modules
Full code
HubSpotConnecting with HubSpot
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Choosing the build path

The best solution is usually the simplest one that meets the business and technical requirements.

Decision order
1

Use no code when the process fits an existing HubSpot capability or native integration.

2

Use low code when the process needs custom logic but can remain within HubSpot automation.

3

Use full code when the solution requires custom interfaces, complex orchestration, or capabilities beyond native tools.

HubSpotConnecting with HubSpot
6

Section 02

Developer Platform

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling

Introduction

The HubSpot Developer Platform provides a common foundation for building, extending, and managing solutions.

  • Organize application code and configuration.
  • Define capabilities through reusable features.
  • Develop and evolve solutions through versioned changes.
  • Move from local development and testing toward deployment
HubSpot developer platform screenshot
DocsDeveloper platform overviewApp configuration
HubSpotDeveloper Platform
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Platform and API versions

A new version of HubSpot’s REST APIs and app developer platform is made generally available every 6 months in March and September.

This is accompanied by a support transition for previous versions.

Version release schedule
v2025.2
Supported
Unsupported
v2026.03
Current
Supported
Unsupported
v2026.09
Beta
Current
Supported
Unsupported
v2027.03
Beta
Current
Supported
Unsupported
v2027.09
Beta
Current
Supported
Unsupported
v2028.03
Beta
Current
Supported
Unsupported
As of Sept 2026 · pick a date above
Betav2027.03
Currentv2026.09
Supportedv2025.2, v2026.03
Unsupported—
DocsPlatform & API versioning
HubSpotDeveloper Platform
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Project structure

DocsApp configuration
my-project-folder/
└─hsproject.json
└─src
└─app/
└─app-hsmeta.json/
└─app-events/
└─my-event-type-hsmeta.json
└─app-objects/
└─my-app-object-hsmeta.json
└─cards/
└─MyCard.jsx
└─my-app-card-hsmeta.json
└─package.json
└─functions/
└─NewFunction.js
└─private-function-hsmeta.json
└─package.json
└─settings/
└─Settings.tsx
└─settings-hsmeta.json
└─package.json
└─telemetry/
└─telemetry-hsmeta.json
└─webhooks/
└─webhooks-hsmeta.json
└─workflow-actions/
└─custom-action-hsmeta.json
HubSpotDeveloper Platform
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App Authentication & Distribution

Choose the authentication model based on the distribution model:

Authentication

Static token: Private access token, rotated every 12 months

OAuth: User authenticated access token, rotated every 30 minutes

Distribution

Private: Limited number of accounts

Marketplace: Publicly available and listed for install

FeatureStatic tokenOAuth
PrivatePrivateMarketplace
API calls✓✓✓
Agent tools✓✓✓
App cards✓✓✓
App pages✓✓✓
App events✕✕✓
App objects✕✕✓
App settings✓✓✓
Custom workflow actions✓✓✓
Public functions for CMS✓✓✕
Serverless functions✓✕✕
SCIM✓✕✕
Telemetry✓✓✓
Webhooks v3✓✓✓
Webhooks v4✕✓✓
DocsAuthentication overviewManage apps
HubSpotDeveloper Platform
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Section 03

HubSpot APIs

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling

Getting data in and out

01

CRM Import/Export

Imports API: Upload CSV/XLSX files to create/update CRM records

Exports API: Generate a CSV/XLSX file of CRM records

02

Data source Import

Data source ingestion API (BETA): These endpoints provide a flexible way to ingest and manage external data without the need to map it to standard HubSpot CRM object schemas.

03

CRM APIs

Create, update, search, upsert & delete records in batches of up to 100 per request

Webhooks can also be registered as part of a HubSpot App for changes to CRM data

DocsImports APIExports APIData source ingestion APIUnderstanding the CRM APIs
HubSpotHubSpot APIs
13

Understanding the CRM APIs

The key six CRM APIs for HubSpot are:

DocsUnderstanding the CRM APIs
01

Object APIs

Create and manage records.

02

Properties API

Create and manage fields.

03

Associations API

Connect records and manage relationship labels.

04

Schemas API

Define and manage custom object structures.

05

Search API

Filter and sort records using properties and associations.

06

Events API

Track occurrences of events for a CRM record on the activity timeline

HubSpotHubSpot APIs
14

API security & usage best practices

Authentication

Static Token or OAuth: For public/private app requests, including user-defined access

Service Keys (BETA): System-to-system integrations

View docs

Scopes

Scopes are defined within your App or Key configuration. You can refer to the API reference documentation to help with selecting the right scopes.

When installing an app, scopes are categorised into 3 types:

RequiredConditionalOptional
View docs

Rate Limits

OAuth / Marketplace apps

110 requests / 10 seconds

Private apps

190 requests / 10 seconds

1,000,000 / day
View docs

Errors & Retries

Inspect the error body; fix auth/validation errors, retry transient 429/5xx failures with backoff, and use correlation IDs to trace issues.

View docs
HubSpotHubSpot APIs
15

Before building, confirm:

If you get stuck, try using the Assistant at developers.hubspot.com/docs

HubSpotHubSpot APIs
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Section 04

Webhooks & Workflow Automation

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling

Using Webhooks in HubSpot

01

Webhook subscriptions

HubSpot sends event notifications to an application. Docs ↗

02

Workflow webhook actions

A workflow sends selected data to an external endpoint. Docs ↗

03

Webhook triggers

An inbound request starts supported HubSpot automation. Docs ↗

HubSpotWebhooks & Workflow Automation
18

Custom code actions

Create serverless functions using Node.JS or Python in a workflow for custom logic to validate, transform, or call an API.

You can use Secrets to store environment variables and API keys to use within Custom Code Actions for integrating with third-party services

Custom code action editor

For inspiration, you can refer to our Data Hub Use Cases

DocsCustom code actions
HubSpotWebhooks & Workflow Automation
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Usage & best practices

Subscribe only to the events you need.
Acknowledge webhook requests quickly.
Validate the sender and store a stable identifier.
Handle duplicates, delays, and failed deliveries.
DocsWebhooks API guideConfigure a webhook subscription
HubSpotWebhooks & Workflow Automation
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Section 05

UI Extensions

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling

Overview

UI Extensions allow you to build custom user interfaces to allow for bespoke business processes and bridge the gap between your CRM and other business applications. These are React-based, built using the UI Extensions SDK.

App cards
01App cards

Context and actions on CRM records.

App pages
02App pages

Broader workflows and guided processes.

Settings pages*
03Settings pages*

Configuration, mappings and connections.

*In the process of transitioning to Pages

HubSpotUI Extensions
22

UI Extensions SDK

  • Access account, extension, and user context
  • Perform actions like displaying alert banners
  • Access context, perform actions, or fetch data using hooks and serverless functions
  • Render the UI through UI components
  • Use tooling for testing, linting, and sharing code
  • Log custom messages for debugging
UI Extensions SDK example
DocsUI extensions SDKLogging & monitoring
HubSpotUI Extensions
23

UI Components

Components reference

When building a UI extension, you can include any number of HubSpot-provided reusable components. These components range from simple text fields to out-of-the-box CRM object reports, and each component offers customization options through properties.

Standard Components

Over 20 components, from text, to buttons to modals

CRM Action components

A built-in set of CRM-related actions, including adding notes to records, creating new records, etc.

CRM data components

Pull data directly from the current CRM record, including information about associated records

App page components

Specific components for your app pages, e.g. PageHeader, PageRoutes, etc.

To help with your first build, you can refer to our Design Patterns, use our Figma Design Kit, or even our Developer MCP Server

HubSpotUI Extensions
24

UI Extension boundaries and best practices

Boundaries

  • No arbitrary HTML or CSS, must use HubSpot-defined Components
  • No access to the DOM, runs in an isolated sandbox

Technical limits

1 MBrequest and response payload limit
15 sdefault fetch timeout

Calls to the HubSpot API count towards your account limits

Best practices

  • Use the @hubspot/eslint-config-ui-extensions for ESLint rules.
  • Use hs project dev when building your UI Extensions to speed up your workflow
  • Use Telemetry to log events and errors to a third-party for monitoring activity
DocsUI extensions overviewAdd telemetryLogging & monitoring
HubSpotUI Extensions
25

Section 06

Serverless Functions

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling

Serverless Functions

Serverless functions let you run backend code in response to events or HTTP requests without managing your own infrastructure.

They are a lightweight, scalable way to validate, transform, and move data between HubSpot and external systems.

Run Node.js logic on demand for UI extensions, workflows, and external integrations.

Custom code snippet
DocsServerless functions overview
HubSpotServerless Functions
27

Public Functions

Called via HTTP from external systems and web apps

Ideal for exposing controlled endpoints to other apps or services, and powering web applications

Private Functions

Called only from within HubSpot UI extensions

Ideal for backend logic that should not be directly accessible over the public internet.

DocsServerless functions overview
HubSpotServerless Functions
28

Limitations & Best Practices

Limitations

  • Functions have a 15 second execution timeout
  • Functions may experience “cold starts” after periods of inactivity.
  • Only privately distributed apps with static auth are currently supported. Apps using OAuth for authentication cannot use serverless functions.

Best Practices

  • Secrets can be stored and recalled for serverless functions via the CLI
  • Use the pre-loaded PRIVATE_ACCESS_TOKEN secret from the function’s app when calling HubSpot’s API
  • Use hs project dev to preview changes and debug errors directly in your terminal.
  • Use Telemetry to log events and errors to a third-party for monitoring activity
DocsServerless functions overview
DocsAdd telemetry
HubSpotServerless Functions
29

Section 07

Developer Tooling

01Connecting with HubSpot
02Developer Platform
03HubSpot APIs
04Webhooks & Workflow Automation
05UI Extensions
06Serverless Functions
07Developer Tooling

Sandboxes in HubSpot

Standard sandbox

  • Schema, assets and limited data copied from production
  • Ability to push select updates to production.
Best for: HubSpot administrators for handling changes to the platform without impacting operations
DocsDeploy sandbox changesAccount types

Developer test account

  • Completely isolated, disposable accounts for testing HubSpot Apps
  • Ability to adjust the HubSpot Subscription to validate its functionality across multiple customer configurations
Best for: HubSpot App developers and Partners for building apps for the marketplace
DocsConfigurable test accounts
HubSpotDeveloper Tooling
31

Tools available to developers

HubSpot CLI

The HubSpot CLI connects your local environment to HubSpot for managing projects within the HubSpot developer platform using your favourite text editors.

View docs

Source control & GitHub Actions

Keep configuration, code, review history and releases in GitHub and use GitHub Actions to automate build and deploy tasks.

View docs

VS Code Extension

Provides a set of tools to streamline local HubSpot development.

View docs

Postman collections

The HubSpot public API workspace in Postman includes API collections for most of the latest versions of the HubSpot REST APIs

View docs

Developer MCP server

The HubSpot Developer MCP server runs locally and provides your AI assistant with tools for streamlining app and CMS development tasks.

View docs

HubSpot Agent CLI

Agents can install and use the CLI to work directly with your HubSpot CRM data and operate on your behalf.

View docs
HubSpotDeveloper Tooling
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Thank you.