I’m currently working on a project involving custom app development and looking to integrate it seamlessly with HubSpot’s CRM and marketing tools.
What are the best approaches or APIs available for connecting a custom-built mobile or web app with HubSpot?
Hey @Suheb the developer documentation has all the documentation on the available apis, to start you’ll need to create a private app to get a key to integrate into your HubSpot portal.
You can also get started with the overview here.
To integrate a custom app with HubSpot, use the HubSpot Public APIs — particularly:
Use HubSpot’s SDKs (Node.js, Python, PHP, etc.) for quicker implementation. Web apps can also leverage HubSpot’s App Marketplace if broader access is needed.
Oliver Kendrick
Adding to what others said, the approach really depends on what kind of custom app you’re building. If it’s a standard web or mobile app, HubSpot’s CRM API and Private Apps setup will cover most of what you need, and OAuth 2.0 handles the authentication side cleanly.
One thing I’d flag though, if your custom app is connected to any hardware or IoT devices (like smart sensors, POS terminals, or connected equipment that logs customer data back into HubSpot), you’re stepping into embedded software development territory, and that changes the integration approach a bit. You’re not just calling APIs from a server anymore, you’re dealing with devices that have limited connectivity, intermittent syncing, and sometimes offline data that needs to queue up before it reaches HubSpot’s CRM.
In that case, I’d recommend building a middleware layer between the device firmware and HubSpot’s webhook/CRM API, so the embedded side handles data collection and buffering, and the middleware handles retries and formatting before it hits HubSpot. Saved me a lot of headaches on a similar project where the device would drop connection mid-sync and duplicate records started piling up.
If it’s a pure software app though, ignore all that, the CRM API plus private app setup is genuinely enough