How to Manage a Successful HubSpot API Integration

By working directly with HubSpot’s APIs, you can create a tailored connection between HubSpot and almost any other software. To help you get started, we’ll explain when a custom API integration is the right solution, the challenges you should prepare for, and the steps to managing an integration that’s built quickly but lasts for the long term.

Put simply, an API (Application Programming Interface) is a way for two systems to talk to each other. A HubSpot API integration means using HubSpot’s APIs to connect HubSpot with another piece of software in a way that suits your business requirements.

There are three main ways HubSpot can integrate with other platforms:

• Native integrations: Ready-made connectors built by HubSpot or partners, designed to be plug-and-play.

• Marketplace apps: Third-party tools that can be installed from the HubSpot App Marketplace.

• Custom API integrations: Bespoke builds that use HubSpot’s APIs to create connections not available out of the box.

It’s this third option we’re focusing on here.

Most businesses start with what HubSpot already provides in its marketplace. However, there are scenarios where a custom API integration is the only way forward.

• No native connector exists. This often happens with industry-specific or proprietary software that hasn’t been widely adopted.

• The available integration isn’t flexible enough. Maybe it doesn’t support all the data fields you need, or it only syncs one way when you require two-way.

• You have unique workflows. For example, importing offline transactions into HubSpot for full revenue attribution, or linking HubSpot with an ERP system to surface account information.

• Future-proofing. As businesses grow, they need integrations that can scale and adapt rather than being limited by what comes out of the box.

In each of these cases, the goal is to create an integration that works reliably in the background, without requiring manual workarounds or constant fixes.

Custom API integrations can be powerful, but they come with considerations that marketing leaders should be aware of.

• Technical complexity. Unlike native connectors, an API integration requires development expertise. You need someone who understands HubSpot’s APIs and the other system’s APIs, too.

• Short-term fixes. It can be tempting to patch together a quick solution, but these often break as soon as processes change or APIs are updated.

• Performance. Poorly designed integrations can create bottlenecks, slow down data syncs, or even hit API rate limits, which currently cap most integrations at 100 requests per 10 seconds per app. Without batching or queuing requests, this can cause sync delays or dropped data.

• Ongoing maintenance. APIs evolve. Without monitoring and updates, an integration that works today may stop working tomorrow.

Recognising these challenges upfront helps you plan for success rather than troubleshooting under pressure later.

Until recently, many developers authenticated HubSpot integrations using API keys. However, HubSpot officially deprecated API keys in 2022 in favour of more secure methods. Today, new integrations must use either OAuth (for apps connecting multiple HubSpot accounts) or private apps (for single-account use cases).

This change improves security and gives businesses more control over how their data is accessed. If you’re scoping a custom HubSpot API integration, it’s essential to use OAuth or private app tokens, not API keys, to ensure your integration is future-proof and compliant with HubSpot’s requirements.

Getting an API integration right is about more than writing code. It requires planning, collaboration, and ongoing management. Here are the core steps.

1. Define clear business objectives

Before any technical work starts, map out what the integration is supposed to achieve. Which teams will use it? Which processes will it support? Which metrics will it impact? Without clear objectives, it’s easy to over-engineer or miss critical requirements.

2. Plan for data mapping and sync rules

Decide exactly what data needs to move between HubSpot and the other system. This includes identifying which fields should sync, how frequently, and whether the integration should be one-way or two-way.

Not all APIs support two-way sync. For example, some external systems may allow HubSpot to read data but not write back to it. Understanding these limitations early will shape your workflows and prevent misaligned expectations.

3. Build for scalability

A good integration isn’t just about solving today’s problem. It should also handle increased data volumes, new fields, and future use cases without needing to be rebuilt from scratch.

4. Test thoroughly before go-live

If you have an Enterprise account, use a HubSpot sandbox for safe testing. Otherwise, create a separate HubSpot portal or staging environment to validate the integration before deploying it live. Check that data flows correctly, error handling works, and no records are duplicated or lost. Involving both marketing and sales teams in testing ensures the integration meets practical needs, not just technical specifications.

5. Monitor and maintain

Once live, schedule regular reviews to check performance and make adjustments. HubSpot releases API updates frequently, and third-party systems evolve too. Building in error logging and notifications ensures you spot issues before they cause bigger problems.

Beyond the technical steps, some principles make the difference between a quick fix and a long-term solution.

• Involve both technical and commercial stakeholders. Developers may understand the APIs, but only marketers and sales teams know which data matters for campaigns, reporting, and lead handoff.

• Document everything. Clear documentation of what the integration does, how it works, and who owns it avoids confusion when teams change.

• Work with certified partners. Specialist partners bring experience across multiple projects and can anticipate pitfalls. This often saves time and cost in the long run.

• Balance speed with sustainability. Yes, integrations should be built quickly to minimise disruption, but they also need to stand the test of time. Cutting corners at the start almost always leads to higher maintenance later.

To bring this to life, here are a few scenarios where businesses have turned to a HubSpot API integration:

• ERP integration. A manufacturing company needed order and inventory data from its custom ERP system visible in HubSpot, so sales reps could see stock availability before quoting.

• Finance integration. A subscription business linked HubSpot with its billing platform so renewals and payment status could trigger marketing and customer success workflows.

• Custom portal integration. A services business created a two-way sync between HubSpot and its client portal, ensuring communications and account data stayed consistent.

These examples illustrate that API integrations aren’t just about convenience; they enable processes that would otherwise be impossible, giving both marketing and sales a more complete picture.

A HubSpot API integration can feel like a technical project, but for marketing leaders, it’s ultimately a strategic one. Done well, it ensures data flows seamlessly, teams have the information they need, and reports can be trusted. Done poorly, it creates friction, errors, and costs more to fix later.

At MarCloud, we work with businesses to scope, build, and maintain HubSpot integrations that support their unique needs, then deliver swiftly, strategically, and with future-proofing in mind. If you’d like to explore how we can help, send us a message.