HubSpot Legacy Public App Creation Sunset: May 26 and June 23, 2026

HubSpot's changelog describes a staged sunset for creating new legacy public apps through the legacy Developer Platform UI. Beginning May 26, 2026, developer accounts created on or after that date cannot use that legacy UI path for new public app creation. Beginning June 23, 2026, the same new legacy public app creation path is disabled for developer accounts created before May 26, 2026.

The practical planning question is narrow: does your team need to create a new public or Marketplace app after these dates? If yes, your review should move toward the Projects-based developer platform and CLI app creation docs. If no, this sunset may still be a reason to plan modernization, but it should not be treated as an immediate breakage event for an existing legacy public app.

For searchers landing here in a hurry, the safe wording is: new legacy public app creation is affected. Existing legacy public apps continue functioning under this specific sunset. Any separate platform migration, Marketplace, or CRM card deadline should be evaluated from its own official source.

Affected: a team that needs to create a new public app through the legacy Developer Platform UI after the relevant account-date cutoff. That team should review the Projects-based app creation path and the CLI project commands before starting new work.

Not affected by this specific event: an existing legacy public app simply continuing to run. That app may still deserve an inventory, migration plan, or Marketplace readiness review, but the May 26 and June 23 dates should not be described as a shutdown date for existing legacy public apps.

Adjacent but separate: apps with classic or legacy CRM cards have their own October 31, 2026 modernization deadline. Keep that card workstream separate from the May/June public app creation sunset so teams do not mix two different official notices.

First, record whether the developer account was created before or after May 26, 2026 and whether the team needs a net-new public or Marketplace app. Second, classify the app state: new app, existing non-project legacy public app, existing project-based app, private app, or CRM card modernization. Third, open the official HubSpot source linked below before selecting a command.

If the work is a new public app, review `hs project create`. If the work is an existing public app that is not already project-based, review the public app migration docs and `hs app migrate` path. If the work is an existing project app, inspect `hsproject.json` and platform-version guidance before deciding whether `hs project migrate` is relevant.

Use this page as a scope guard. It helps prevent both underreaction and overreaction: do not ignore the creation sunset if you build new public apps, and do not tell stakeholders that existing legacy public apps stop functioning on May 26 or June 23, 2026.