Decide whether this is a creation issue or a modernization issue.
Legacy Public App vs Projects App
The sunset is about creating new legacy public apps. Projects-based apps are the path HubSpot directs new public app development toward.
Last source check: 2026-05-24
Citation Summary
Use this page as an unofficial, source-linked planning reference for decide whether this is a creation issue or a modernization issue. The key takeaway is: The sunset is about creating new legacy public apps. Projects-based apps are the path HubSpot directs new public app development toward.
Suggested citation: Projects App Guide, "Legacy Public App vs Projects App," last source check 2026-05-24, https://projectsappguide.com/hubspot-legacy-public-app-vs-projects-app
Answer Snapshot
- Short Answer
- The key distinction is creation versus modernization: the May/June 2026 sunset affects new legacy public app creation, while migration decisions depend on the existing app state.
- Applies To
- Stakeholders deciding whether a HubSpot app needs new app creation, modernization, migration planning, or a separate card workstream.
- Verify
- Compare the sunset changelog with the create-app and migration overview docs before telling a client what changed.
- Boundary
- Do not collapse all older HubSpot app work into one migration deadline.
Independent educational guide. Not affiliated with, endorsed by, or sponsored by HubSpot. Verify critical commands and platform behavior against official HubSpot documentation before deploying.
The difference that matters
A legacy public app and a Projects-based app are not just two labels for the same workflow. The May/June 2026 changelog is about the ability to create new legacy public apps through the legacy Developer Platform UI. The Projects-based developer platform uses CLI and file-based project configuration for new app development.
This distinction matters because stakeholders often compress the announcement into a vague deadline. The safe planning statement is narrower: new legacy public app creation is being disabled; existing legacy public apps continue functioning under that specific sunset.
When you explain this to a client or internal team, separate three questions: Do we need a new public app? Do we need to modernize an existing app? Do we have a separate Marketplace or CRM card deadline?
Legacy public app creation
Legacy UI creation is the path being sunset for new public apps. If a team was planning to create a new public app from the old UI, they should shift their planning to the Projects-based CLI app creation flow.
For existing legacy public apps, the right next step is usually inventory and risk review, not panic migration language. Document installs, OAuth behavior, scopes, webhooks, CRM cards, Marketplace status, and any modernization timeline before assigning a command path.
If the existing app is not project-based and modernization is desired, review the public app migration docs and `hs app migrate` guidance. Do not assume a new-app creation flow is the same as migrating an existing app.
Projects-based app development
Projects-based apps use file-based configuration and HubSpot CLI workflows. That makes the project easier to review in source control, pass through CI checks, and hand off between developers compared with an undocumented UI-only process.
The main planning artifacts are the project files, platform version, app schema/config files, auth configuration, and the commands used for creation, upload, local development, and migration. Those artifacts should be reviewed together instead of scattered across chat notes.
A good handoff ends with the likely path to verify, relevant official source links, and open questions. It should not end with a guaranteed command, because the correct path depends on app type, project state, platform version, and current official docs.
Claim / Source Map
These are the main claims this page relies on. Re-open the linked official HubSpot source before production-affecting commands, uploads, submissions, or client delivery.
| Claim | Official source |
|---|---|
| The legacy public app sunset concerns new legacy public app creation. | Legacy Public App Creation Sunset |
| New Projects-based app development should be reviewed from the create-app docs. | Create a new app using the CLI |
| Existing app migration paths should be evaluated from migration documentation. | Determine your migration path to 2026.03 |
FAQ
Is the legacy public app sunset the same as a migration deadline?
No. The May and June 2026 sunset affects new legacy public app creation. Migration and platform-version work should be evaluated from the relevant migration sources.
How do I explain the difference to a client?
Separate new app creation, existing app modernization, Marketplace readiness, and CRM card modernization as different workstreams with different official sources.
Download the 2-page checklist
Use the affected/not affected table, command map, and preflight checklist before choosing a path.
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