What This Update Actually Is
HubSpot is closing the door on creating new legacy public apps through the Developer Platform UI. This is a permanent change, not a soft deprecation.
The rollout happens on two dates. If your developer account was created on or after May 26, 2026, you lose the ability to create legacy public apps immediately. If your account existed before that date, the cutoff is June 23, 2026.
Three things are not changing right now: your existing legacy public apps, legacy private apps, and the migration path for existing apps. HubSpot has committed that migration of existing legacy public apps is a separate initiative with its own timeline and tooling.
The only action that disappears is creating a new legacy public app. All new app creation for marketplace-listed apps now routes through the Projects-based platform and HubSpot CLI.
Why HubSpot Shipped This
Legacy public apps were built on an older architecture. HubSpot's own documentation on this update calls it increasingly difficult to secure and maintain. That's a candid admission, and it matters.
The deeper driver is that HubSpot wants every app in its marketplace built on infrastructure it actively invests in. The Projects-based platform gives developers CLI-based workflows, UI extensions, app cards, and stronger deployment tooling. Building new apps on the legacy system would mean starting with a foundation HubSpot is pulling away from.
For the HubSpot ecosystem as a whole, this move raises the security floor. Every new marketplace app will be built on a platform with a clear long-term roadmap, which protects the humans relying on those integrations.
How to Use It Step by Step
If you're a developer planning to build a new public app, here's the path forward.
- Install the HubSpot CLI if you haven't already. You'll need Node.js and a developer account. Run npm install -g @hubspot/cli and authenticate with hs auth.
- Create a new project using hs project create. Choose the app template that matches your use case. This scaffolds the Projects-based structure you'll build inside.
- Review HubSpot's developer documentation for Projects-based apps at developers.hubspot.com. The public app quickstart walks you through scopes, OAuth, and your first deployment.
- Use hs project deploy to push your app to your developer sandbox and validate behavior before submission.
- Submit to the HubSpot App Marketplace through the Developer Platform UI once your project-based app is ready. The listing and review process is unchanged.
If you have an existing legacy public app, do nothing right now. Wait for HubSpot's dedicated migration tooling and timeline. Don't attempt a manual migration without guidance; you risk breaking live integrations.
What It Touches in Your HubSpot Strategy
For most portal admins and marketing ops leaders, this update is a background event. If your stack runs on installed marketplace apps built by third-party vendors, those apps keep running. Nothing breaks on your side.
The ripple is felt most in three places.
- Internal development teams building custom HubSpot integrations for their own organization must shift all new public app work to the Projects platform immediately.
- HubSpot Solutions Partners and ISVs who build and maintain marketplace apps need to stop scoping new apps on the legacy architecture now, even before the hard cutoff date.
- RevOps leaders planning integration roadmaps should factor in a learning curve for any developer resources being asked to build on the Projects platform for the first time.
Key Takeaway
Your existing legacy public apps are fully protected. This sunset only removes the ability to create new ones. Don't let urgency around the headline push you into an unnecessary migration right now.
There's also an indirect signal here for anyone managing a complex portal. When HubSpot tightens its app ecosystem, it often follows with more aggressive enforcement of app security standards. If your portal relies on a high volume of third-party integrations, this is a good moment to run a full audit.
Our HubSpot portal audit checklist covers integrations alongside workflows, data quality, and every hub so you can spot risk before it becomes a real problem.
Key Takeaway
The Projects-based platform isn't just a replacement. It brings UI extensions, app cards, and CLI-based deployments that legacy architecture never supported. New apps built here will be more capable, not just more compliant.
Who Should Care Most
This update is high-priority for a specific slice of the HubSpot community and genuinely low-stakes for everyone else.
- HubSpot app developers and ISVs: stop any in-flight work scoped for the legacy public app creation flow. Redirect it to Projects-based tooling before the hard cutoff.
- Solutions Partners building custom integrations for clients: update your delivery methodology and developer onboarding docs to reflect Projects as the default.
- RevOps and operations leaders at mid-market and enterprise companies: flag this to any developer resources on your team who handle HubSpot integrations.
- Marketing ops managers using marketplace apps day to day: no action needed. Your installed apps are not affected.
Companies with integration-heavy portals should note this as the start of a longer transition. The migration tooling for existing legacy public apps is coming. Humans managing those portals will want to plan capacity for that work when it arrives.
George's Take
I've watched HubSpot manage platform transitions for years, and this one is handled more cleanly than most. They're not pulling the rug. They're closing one door, leaving everything behind it intact, and pointing clearly to the new door. What I'd tell any developer or RevOps leader right now is this: don't confuse the headline with an emergency. Your existing apps are fine. But if you've been planning to build something new, start it on Projects today, not the day before the deadline. The developers we work with who've already made the switch report that the CLI tooling and UI extensions are genuinely better, not just different. This isn't a step down. It's a step forward that HubSpot finally made mandatory.
“Don't confuse the headline with an emergency. Your existing apps are fine. But if you're planning to build something new, start it on Projects today, not the day before the deadline.”
Plan Ahead With a Sidekick Strategy Session
Platform transitions like this one reward teams that plan early. If you're managing a HubSpot portal with active integrations and aren't sure how this sunset fits into your roadmap, a focused strategy call with the Sidekick team is the fastest way to get clarity. We help humans figure out what needs action now, what can wait, and how to build integration strategy that holds up as HubSpot evolves. Not sure if you need outside help? Read our honest guide on when a HubSpot implementation partner actually makes sense and then reach out if it resonates.
Frequently Asked Questions
Will my existing HubSpot legacy public apps stop working after June 23, 2026?
No. Existing legacy public apps are fully unaffected by this change. They'll continue to function exactly as they do today. The sunset only removes the ability to create new legacy public apps. A separate migration initiative with its own timeline will address moving existing apps to the new platform in the future.
What is HubSpot's Projects-based app platform?
It's HubSpot's current developer platform for building public apps. It uses the HubSpot CLI for local development, supports UI extensions and app cards, and offers better deployment tooling than the legacy architecture. All new marketplace-listed apps must be built here starting May 26 or June 23, 2026, depending on account age.
Does this change affect legacy private apps?
No. The sunset specifically targets new legacy public app creation. Legacy private apps are not impacted at this time. HubSpot confirmed this explicitly in the update documentation. If you're running private apps for internal integrations, no action is needed on your end right now.
What's the exact cutoff date for my developer account?
If your developer account was created on or after May 26, 2026, legacy public app creation is disabled on that same date. If your account existed before May 26, 2026, your cutoff is June 23, 2026. After those dates, new app creation must happen through the Projects-based platform and HubSpot CLI.
Do I need to migrate my existing legacy public apps right now?
No. HubSpot has stated that migration of existing legacy public apps is a separate initiative with its own timeline and dedicated tooling. You don't need to act today. When migration tooling is available, HubSpot will communicate the process. Attempting a manual migration now carries unnecessary risk.
How does the HubSpot Projects platform differ from legacy public apps for developers?
The Projects platform supports CLI-based workflows, UI extensions, app cards, and more robust deployment tooling. Legacy public apps were built on older architecture that HubSpot no longer invests in. The new platform gives developers access to a richer feature set and a clear long-term roadmap backed by active HubSpot investment.
