HubSpot legacy APIs and apps: the 2027 deadlines explained

If your HubSpot portal relies on an integration, a custom app or a private app token, the clock is now running. On 15 September 2026 HubSpot announced that v1 to v3 APIs, legacy public apps and legacy private apps will become unsupported, with enforcement in September 2027. Version 4 APIs lose support even sooner, on 30 March 2027, and apps built on Projects 2025.2 need to move to 2026.09 by March 2027.

That leaves about four to five months for the early deadlines and under a year for the main one. This guide explains what is changing, how to find out whether you are affected, and a sensible order of work for the migration.

What HubSpot announced, in plain terms

HubSpot is moving its whole developer platform to date-based versions. APIs and developer projects now get two major releases a year, in March and September, and each version is supported for 18 months. The current platform version at the time of writing (November 2026) is 2026.09, released on 8 September 2026.

Alongside that, three older things are being retired:

• API versions v1, v2 and v3. Endpoints on /v1/, /v2/ and /v3/ paths move to unsupported status. HubSpot says it will no longer release bug fixes, reliability improvements or security updates for them.
• Legacy public apps. Public apps built on the older, pre-Projects architecture. New legacy public apps could no longer be created from 23 June 2026.
• Legacy private apps. Private apps created before the Projects-based model. Creation of new legacy private apps ended on 28 September 2026 for new accounts and 26 October 2026 for existing accounts.

Scopes are changing too: HubSpot says new apps must use granular scopes from 8 September 2026. Broad scopes for HubDB, tickets, timeline and files are being replaced with separate read, write, publish and delete permissions, and HubSpot's partner recap says the current scopes sunset in March 2027.

The key dates at a glance

If you still have a classic CRM card on a record page, check it now: HubSpot's migration timeline said static legacy cards would stop rendering after 31 October 2026.

Who this affects

You are likely affected if any of these sound familiar:

• A developer or agency built a custom integration between HubSpot and your ERP, ecommerce platform, booking system or internal database.
• Your website forms, CMS modules or serverless functions call the HubSpot API directly.
• Someone created a private app in your portal to get an access token for a script, a reporting tool or a Zapier-style workflow.
• You sell or maintain an app on the HubSpot Marketplace.

Marketplace apps face the clearest consequences. After September 2027, an app making unsupported API calls loses its certification, and an app still on the legacy architecture becomes eligible for delisting. For in-house integrations, "unsupported" means no more fixes or security updates, which is a real operational risk even if the endpoint keeps answering for a while.

How to check whether you are affected

1. 1 Open Developer Home. Since 15 September 2026, a tasks card shows how many of your apps call APIs that are going unsupported. HubSpot detects this from runtime calls, not from your source code, so an app can be flagged even after you think you have updated it.
2. 2 List your legacy apps. In your HubSpot account, go to Development and choose Legacy apps in the left sidebar. Anything listed there is on the old architecture.
3. 3 Check your projects. For apps built with the HubSpot CLI, open hsproject.json and look at platformVersion. Anything older than 2026.09 has a deadline attached.
4. 4 Search your codebase. Look for API paths containing /v1/, /v2/, /v3/ and /v4/, including inside website JavaScript and CMS serverless functions.
5. 5 Ask your vendors. If a third-party connector touches HubSpot, ask the vendor for their migration plan and date in writing.

A sensible migration order

HubSpot's advice is to migrate straight to date-based versioning rather than stepping through v3 or v4 first. That saves doing the work twice. A practical order of work looks like this:

1. 1 Fix anything with a near deadline. The Pipelines API v1 sunset on 4 December 2026 comes first. Then Projects 2025.2 apps and v4 calls before March 2027.
2. 2 Replace legacy private app tokens. For lightweight integrations and internal tools, HubSpot points to Service Keys, which are scoped API credentials with activity logging and key rotation. They were announced in public beta in September and are found under Settings, Integrations, Service Keys.
3. 3 Move custom apps onto Projects 2026.09. Update platformVersion, switch to granular scopes, and rebuild any classic CRM cards as React-based app cards. If your app uses serverless functions, those have been supported again since version 2026.03.
4. 4 Consider user-level apps. Version 2026.09 lets an app act with the permissions of the person using it, not the person who installed it, by setting isUserLevel: true. Audit logs then show "user via app". Some newer APIs, such as the expanded Sequences API, require this.
5. 5 Test, then watch the tasks card. Because detection is based on real traffic, the Developer Home card is a useful confirmation that old endpoints are no longer being called.

If your local tooling is out of date too, our post on the HubSpot CLI and Node 20 end of support covers the Node.js side of the same clean-up.

Treat September 2027 as the last date, not the target. The March 2027 deadlines arrive first.

Frequently asked questions

Will my integration stop working on the deadline?

HubSpot describes these versions as becoming unsupported, which means no bug fixes or security updates. It has not promised that endpoints will keep working indefinitely, so plan to finish migrating before September 2027 rather than relying on them.

Can I still create a private app?

Not a legacy one. Legacy private app creation ended in September and October 2026. Use Service Keys for simple token-based access, or build a Projects-based app if you need more.

Do HubSpot CMS websites need changes?

Standard pages, templates and modules do not. Sites that call HubSpot APIs from JavaScript or serverless functions should be checked for old API paths.

How long is each new version supported?

Each date-based version is supported for 18 months after release, so a version adopted today still needs a planned upgrade later.

Need help with your HubSpot integrations?

We audit and rebuild HubSpot apps, private app integrations and CMS functions on the current developer platform, alongside our wider HubSpot development services. For context, see our HubSpot CMS website for a global payments platform, or read about Node.js integrations between Shopify, HubSpot and your CRM. If you would like an inventory of what needs migrating, get in touch.

Sources: HubSpot changelog: Legacy APIs and apps, Fall 2026 Spotlight, Platform versioning, Migration timeline, Pipelines API v1 sunset, UNBOUND 2026 partner recap