Basics & Onboarding

Your Starting Point for Building on the HubSpot Developer Platform

One unified foundation to build apps, extend Smart CRM and ship custom integrations. From creating your first project to migrating existing apps, this is your starting point for building and delivering value faster on HubSpot.

Choose Your PathRead the Announcement
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Are your existing apps on the new platform? See key dates and decision framework →   View timelines

What's New

One platform. Built to scale with you.

The HubSpot Developer Platform gives you one set of tools to build apps, integrations and custom experiences on HubSpot.

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Ship Faster

Guided setup → hello world in minutes. Modern CLI, AI-native docs, no boilerplate.

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Build AI-Ready

Powered by one unified data foundation. Your experiences surface natively across CRM, workflows and AI tools.

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Stay Current

18-month support windows, clear upgrade paths, investment protection. Future beta programs.

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Reach More Customers

Distribute to 228k+ HubSpot customers through the HubSpot Marketplace.

  • Ship your first integration in minutes

    • Guided setup with hs get-started
    • AI-native docs that answer your questions
    • One codebase → private or Marketplace

  • Uplevel existing apps with more value

    • Keep existing installs and OAuth
    • Unlock App Home, App cards, AI capabilities
    • Clear timelines with 18-month support windows

Building Blocks

What You Get What It Does Get Started
Projects

Unified framework for apps + CMS assets
hs get-started
UI Extensions
App cards, App Home, settings pages (React)
APIs & Webhooks
RESTful APIs, webhooks, and OAuth for any integration
Serverless Functions
Backend logic without managing infrastructure (Node.js)
App Objects & App Events
Custom data models that work across tiers
Breeze Agent Tools
Turn workflow actions into AI agent capabilities
MCP Server
Bring HubSpot data to your IDE copilot

2025.2, 2026.03

Choose Your Path

What are you trying to do?

Select your starting point and we'll guide you through the right steps.

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Start fresh with the latest platform version and best practices.


Your Day 0:

1. Create Account
Sign up for a free HubSpot account.
Sign up

2. Run hs get-started 

Authenticate and create your first project with guided setup.
Quickstart guide

3. Build Your App
Add UI extensions, workflow actions or API integrations.
Create an app

4. Upload & Deploy

Upload your project and deploy to HubSpot.
CLI project reference


See what you can build
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Migrate to the new platform and unlock new capabilities.


Your Day 0:

1. Convert Portal (if needed)

Opt in to the new platform if using legacy Developer Tools.
Portal conversion guide 


2. Find Your Migration Path
Identify your app type, platform version, and serverless usage.
Check the migration matrix 

3. Review Requirements
Understand what migration involves for your app type.
Migration guide

4. Run Migration
Legacy: hs app migrate
Projects 2025.1: hs project migrate
CLI migration commands 


Read the migration case study
Start Building

Resources to Get Started

Docs, tutorials and videos organized by what you're trying to accomplish.

Showing 1 - 6 of 21

  • Docs

    Starting Fresh

    Docs

    Starting Fresh

    Developer Platform OverviewArchitecture, capabilities, and core concepts.
    View Docs

  • Tutorial

    Starting Fresh

    Tutorial

    Starting Fresh

    Getting Started with ProjectsDetailed walkthrough of creating your first project.
    Watch

  • Tutorial

    Starting Fresh

    Tutorial

    Starting Fresh

    Create an App CardStep-by-step guide to your first UI extension.
    View Docs

  • Docs

    Portal Conversion

    Docs

    Portal Conversion

    Portal Conversion 101Everything you need to opt in to the new HubSpot Developer Platform and convert a legacy developer portal to a HubSpot Free CRM account.
    View Docs

  • Video

    Migrating Your Apps

    Video

    Migrating Your Apps

    How to Convert Your Portal to the New Developer PlatformDetailed walkthrough covering portal conversion to HubSpot’s unified Developer Platform.
    Watch

  • Changelog

    Migrating Your Apps

    Changelog

    Migrating Your Apps

    Legacy Developer Accounts Migrating to the Unified Developer PlatformKey dates and info for planning legacy developer accounts conversion to HubSpot’s unified Developer Platform.
    Read More
FAQs

Common Questions

Quick answers to help you get started.

The HubSpot Developer Platform is a unified foundation that empowers you to build and deliver value faster — one way to build on HubSpot, from private integrations to Marketplace apps. It includes the CLI, projects framework, UI extensions, and APIs plus an AI‑ready framework and capabilities like Breeze Agent Tools. 

Projects are the unified framework for building apps (and CMS assets) on the HubSpot Developer Platform: unified projects that can support one account or many. A project is a collection of code, configuration, and assets managed through the CLI with date-based versioning (like 2026.03).

Both follow the same 6-month release cycle: March and September. Each platform version is supported for 18 months, giving you ample time to plan upgrades. API versioning is independent meaning you can use newer APIs on older platform versions.

Check the changelog for release announcements and deprecation notices. Subscribe for updates

No. You can create a free HubSpot account and build apps without a paid subscription. You'll get access to a developer test account with sample data for testing. For production deployments, your app's users will need appropriate HubSpot accounts.

A free developer account includes:

  • Test accounts with sample CRM data (contacts, companies, deals) for development and testing
  • API access to HubSpot’s public APIs for development and testing
  • App management to create, configure, and publish apps
  • CLI access to create and deploy Projects
  • AI-native developer documentation

Test accounts reset periodically but are fully functional for building and testing your integrations.

When you convert your developer portal, you get 2 Super Admin core seats with full access to CRM and development tools. Additional users can be added as developer seats which provide access to development tools without using a paid CRM seat.

Developer seats let your team collaborate on apps without requiring paid HubSpot subscriptions.

Learn more about account types

  • UI Extensions: React (TypeScript or JavaScript)
  • Backend integrations: Any language that can make HTTP requests; HubSpot's APIs are RESTful
  • CLI tooling: Node.js
  • Serverless functions: Node.js (currently supported on Projects 2025.1; see docs for the latest roadmap and migration guidance)
  • AI tooling: MCP server support for IDE copilots (Cursor, Claude Code, VS Code, Windsurf)

Check the platformVersion field in your hsproject.json file. Apps on version 2025.2 or later are on the current platform.
If you're on an earlier version, see the "I have an existing app" path above to upgrade to the latest Projects framework.

Note: Version numbers are date-based. Use 2026.03 (March), not 2026.3.

The new platform offers better performance, modern UI Extensions (app cards, App Home, settings pages), improved developer tooling, and ongoing feature updates including AI capabilities.

Legacy apps on older versions will be deprecated over time. Projects 2025.1 deprecates June 1, 2026. Migrating ensures your app stays supported and can take advantage of new capabilities.

See the migration timeline

They're separate steps: Portal conversion updates your developer portal itself — converting it from the legacy Developer Tools view to a HubSpot Free CRM account with the Development navigation. This is a one-time step that must be completed before you can migrate apps.

App migration moves individual apps to the new Projects framework (2025.2 or later). Each app migrates separately using CLI commands. If your portal is already on the new platform (you see "Development" in the nav), you can skip portal conversion and go straight to app migration.

Migration moves your app to the new Projects framework. What's involved depends on where you're starting:
  • Legacy public apps use OAuth and can be installed in multiple portals; they may or may not be listed in the Marketplace.
  • Legacy private apps use API keys and work only in a single portal.
This distinction affects your migration path and install limits. If you’re still using a legacy developer portal, you’ll convert that portal to the new Developer Platform through the in‑app opt‑in banner then move individual apps using the migration guides.

See the migration matrix guide

Yes, Classic CRM cards sunset on October 31, 2026. App cards are the replacement — they're built with React, support richer interaction and work across more surfaces (record pages, App Home, settings).

If you're migrating an app that uses classic CRM cards, you'll need to rebuild them as app cards.

Classic CRM cards sunset details
Create an app card

Serverless functions are currently supported only in Projects 2025.1. They're not yet available on 2025.2 or later.

What this means for you: New apps should build without serverless for now or start on 2025.1 and migrate later. Existing apps using serverless should stay on 2025.1 until 2026.03 (March 2026).

We'll share updates on 2026.03 serverless support in the changelog.
Read serverless migration strategies

If you're already on Projects 2025.1 with app cards → migration to 2025.2 or later is lightweight.
If you're on a legacy app with significant tech debt → starting fresh might be faster.

Run hs project migrate to see what's involved.

Ready to Build?

Access Your HubSpot Account to Get Started