HubSpot's September 2027 API deadline
What's changing, what "unsupported" really means, where old API calls tend to hide in a HubSpot account, and how to check yours.
The short version. HubSpot has replaced its numbered API versions (v1, v2, v3, v4) with dated versions like 2026-03. Its migration guide says the numbered versions will no longer be supported from September 2027. Anything your team built that calls HubSpot's API, including code inside workflows, should be checked and moved before then.
What's changing
HubSpot now names API versions by date, in a YYYY-MM format, instead of v1 through v4. In the address of an API call, that looks like this:
Three rules come with the new system:
- New versions arrive twice a year, in March and September.
- Each version is supported for 18 months. The first 6 months get bug fixes and improvements. The next 12 get critical fixes only, such as security issues.
- Breaking changes only ship in a new version. A version you're on won't change under you, but staying on it past its 18 months means it stops being looked after.
What happens to the old versions
HubSpot's legacy API migration guide says that in September 2027, all APIs using the old numbered versions (v1, v2, v3 and v4) will no longer be supported. HubSpot's developer blog puts v4 on that path even earlier, at its spring 2027 release.
Unsupported doesn't mean switched off on day one. HubSpot says unsupported versions may keep working, but they're no longer guaranteed critical fixes. In practice, that means anything still on them can break at any time, and nobody at HubSpot is obliged to fix it.
HubSpot also notes that some older v1 and v2 endpoints don't yet have exact replacements in the dated versions, so some migrations take more than a find-and-replace.
Where old API calls hide
The risky code is rarely in one place. Check each of these:
- Custom code steps inside workflows. The most common spot, and the easiest to forget, because the code is tucked inside a workflow nobody opens.
- Scripts outside HubSpot. Scheduled jobs on a server, a laptop or a cloud function that use a HubSpot token.
- Code steps in Zapier, Make and similar tools. These often call HubSpot directly.
- Apps from HubSpot's marketplace. These are the vendor's job to update, but it's worth confirming each one has a plan.
How to check your account yourself
- List every workflow with a custom code step. Include workflows that are switched off, since someone may turn one back on.
- Search the code for old version numbers. Look for
/v1/,/v2/,/v3/and/v4/in any address that includesapi.hubapi.com, and forhapikey, a login method HubSpot retired years ago. - Find scripts outside HubSpot. Ask who has created private apps or access tokens in your HubSpot settings, and what each one is used for.
- Ask your marketplace app vendors whether they've moved to the dated versions.
- Plan the moves in order of risk, starting with workflows that touch leads, owners and revenue.
- Put March and September on the calendar. New versions will keep arriving every six months, so this becomes a routine check rather than a one-off project.
Or let RimeGuard do it
RimeGuard's free health check does the first three steps for you. It reads every workflow, including the code in custom code steps, flags each call to a retiring API, and gives you a plain-English list of what to move and how. After that, it keeps watching for each March and September release.