HubSpot Custom API and webhooks integration: connect the systems no marketplace connector covers
When an off-the-shelf connector fits, we install it. When it does not, we build the integration on HubSpot's REST APIs and webhooks: contacts, companies, deals and custom objects moving both ways, with clear logging when a sync fails.
Honest fit
Connector, or custom API and webhooks
A marketplace connector exists and fits
If a certified connector already covers your system and your data model, that is the cheaper, faster path and we say so. We configure it, map fields and move on. No point building code where a maintained connector does the job.
No connector, or the connector is too shallow
Many B2B systems have no HubSpot connector, or one that syncs contacts but ignores custom objects, quotes or your internal IDs. We build on HubSpot's REST APIs and webhooks so the fields you actually report on move too.
Event-driven, not a nightly batch
When a HubSpot record changes and another system needs to know within seconds, we use webhooks. HubSpot notifies your endpoint on contact, company and deal creates, deletes and property updates, up to 1,000 subscriptions per app (HubSpot docs).
What actually syncs
The data and events we move between HubSpot and your systems
Contacts, companies, deals, custom objects
- - Standard objects plus custom objects you defined
- - Associations between them, not just flat records
- - Read and write both directions via REST API
- - Your internal IDs mapped, so records match on both sides
Webhook notifications on change
- - Fires on create, delete and property update
- - crmObjects subscriptions for most CRM object types (HubSpot changelog)
- - Your endpoint receives the event within seconds
- - Lightweight to set up, quick to extend
API pulls for reports and reconciliation
- - Retrieve specific records or full lists on demand
- - Best when you need data or an action, not a notification (HubSpot docs)
- - Nightly reconciliation to catch missed events
- - Rate-limit aware, so large pulls do not stall
Outbound webhooks from HubSpot workflows
- - A workflow calls your external endpoint mid-process
- - Route to a serverless function, for example AWS Lambda behind API Gateway (HubSpot docs)
- - Enrich, validate or push to an ERP
- - Result written back to the HubSpot record
Private app built the current way
- - Webhooks defined in a private app via developer projects (HubSpot changelog)
- - Built on current API versions, not deprecated v1 or v4 (HubSpot changelog)
- - OAuth on supported endpoints, not the sunset v1 OAuth (HubSpot changelog)
- - Documented so your team can maintain it
Fails loudly, retries where safe
- - Errors surface to a channel you watch, not a silent log
- - Retries and dead-letter handling for transient failures
- - Reconciliation catches events dropped on either side
- - You know a sync stopped before your reporting drifts
Questions we get
HubSpot custom API and webhooks, answered
Webhook or API: which one do we need?+
Use a webhook when another system must react to a change in HubSpot, and an API call when you need to fetch specific data or perform an action inside HubSpot. HubSpot's own guidance draws the same line: webhooks push notifications on events, APIs retrieve or update on demand (HubSpot docs). Most real integrations use both.
What HubSpot events can trigger a webhook?+
Contact, company and deal creations, deletions and property updates, among other CRM object types. You subscribe to the events you care about, up to 1,000 subscriptions per app (HubSpot docs). Newer setups define these subscriptions in a private app via developer projects using a webhooks.json file (HubSpot changelog).
Do you build integrations where no connector exists?+
Yes, that is the point of this service. When a maintained marketplace connector fits, we use it. When your system has no connector, or the connector ignores custom objects and the fields you report on, we build directly on HubSpot's REST APIs and webhooks so the right data moves both ways.
Where does the integration code actually run?+
On infrastructure you can point at: a serverless function, a small service, or a private app. A common pattern is a HubSpot workflow calling a webhook that hits an endpoint, for example AWS Lambda exposed through API Gateway, which processes the event and writes back to HubSpot (HubSpot docs).
How do you handle HubSpot API rate limits on large syncs?+
We stop well below the ceiling and reserve headroom for retries. HubSpot's APIs have per-app limits, and pushing to the edge risks odd counter behavior and failed calls, so a bulk pull is throttled and, where possible, scheduled off your integrations' peak windows. Reconciliation catches anything a burst missed.
Will this break on HubSpot's API changes?+
We build on current, supported API versions. HubSpot is deprecating v1 and v4 APIs and sunsetting legacy OAuth and public app creation (HubSpot changelog), so integrations built on those need attention. We also flag upcoming breaking changes, such as pipeline stage delete validation from the 2026-09 API version (HubSpot changelog).
Can you fix an integration someone else built?+
Yes. We start with a portal audit to map what the current integration touches, where it drops data and what runs on deprecated endpoints, then propose a fix list with effort estimates. If the sync is silently losing records, that is usually where reconciliation and loud error handling go in first.
Next step
Where this fits in the wider build
Automations
Make.com when no-code fits, custom Node or Python when it does not. Integrations built to run unattended and fail loudly when they should.
One clean source of truth
An integration only helps if the data model underneath it is clean. Data sync, deduplication and modeling so records match across systems.
Audit an existing integration
A two to three week structured review of your portal, including where syncs drop data. Output is a scorecard plus a prioritised fix list with effort estimates.
30 min discovery call
Tell us which system needs to talk to HubSpot
Walk us through the stack and the data that has to move. We come back with an honest read on connector versus custom, and a scope.