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description: Onboarding starting point for new and existing developers building on the HubSpot Developer Platform. Step-by-step guides to create your first project or migrate your existing apps.
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[content]
Developer Platform Basics & Onboarding
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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 Path
Read the Announcement
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.
Ship Faster
Guided setup → hello world in minutes. Modern CLI, AI-native docs, no boilerplate.
Build AI-Ready
Powered by one unified data foundation. Your experiences surface natively across CRM, workflows and AI tools.
Stay Current
18-month support windows, clear upgrade paths, investment protection. Future beta programs.
Reach More Customers
Distribute to 228k+ HubSpot customers through the HubSpot Marketplace.
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Ship your first integration in minutes
Available
Guided setup with hs get-started
AI-native docs that answer your questions
One codebase → private or Marketplace
Uplevel existing apps with more value
Available
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)
Quickstart
APIs & Webhooks
RESTful APIs, webhooks, and OAuth for any integration
API overview
Serverless Functions
Backend logic without managing infrastructure (Node.js)
Strategies
App Objects & App Events
Custom data models that work across tiers
Overview
Breeze Agent Tools
Turn workflow actions into AI agent capabilities
AI Tools
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Bring HubSpot data to your IDE copilot
Setup
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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.
I'm new here
I have an existing app
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
Migrate to the new platform and unlock new capabilities.
Your Day 0:
1. Find Your Migration Path
Identify your app type, platform version, and serverless usage.
Check the migration matrix
2. Review Requirements
Understand what migration involves for your app type.
Migration guide
3. Run Migration
Legacy: hs app migrate
Projects 2025.1: hs project migrate
CLI migration commands
Read the migration case study
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Resources to Get Started
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Architecture, capabilities, and core concepts.
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Tutorial
Starting Fresh
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Detailed walkthrough of creating your first project.
Watch
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Tutorial
Starting Fresh
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Step-by-step guide to your first UI extension.
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Portal Conversion
Docs
Portal Conversion
Portal Conversion 101
Everything you need to opt in to the new HubSpot Developer Platform and convert a legacy developer portal to a HubSpot Free CRM account.
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Video
Migrating Your Apps
Video
Migrating Your Apps
How to Convert Your Portal to the New Developer Platform
Detailed walkthrough covering portal conversion to HubSpot’s unified Developer Platform.
Watch
Changelog
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Migrating Your Apps
Legacy Developer Accounts Migrating to the Unified Developer Platform
Key dates and info for planning legacy developer accounts conversion to HubSpot’s unified Developer Platform.
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FAQs
Common Questions
Quick answers to help you get started.
What is the HubSpot Developer Platform?
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.
What are Projects?
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
).
When are new platform versions and APIs released?
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
Do I need a paid HubSpot account to develop?
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.
What does a developer account come with?
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.
What are developer seats?
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
What languages and frameworks are supported?
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)
How do I know which platform version I'm on?
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
.
Why should I migrate my existing app? When is the best time?
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
What’s the difference between portal conversion and app migration?
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.
What does “migration” mean for my app?
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
Do I need to migrate from legacy CRM cards to app cards?
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
What’s the status of serverless functions?
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
Should I migrate or start fresh?
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
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