| Google Cloud Platform (incl. Firebase & Vision) | United States (us-central1) | Hosts application workloads on Cloud Run and Cloud Functions, stores data in Firestore/Cloud Storage, performs OCR with Vision API, and provides Firebase Authentication (including Google sign-in). | Cloud infrastructure & data processing | Required |
| Elastic Cloud (App Search) | United States (us-central1) | Indexes and searches customer documents via Elastic App Search. | Search & analytics | Required |
| Amazon Web Services (SES & S3) | United States (us-east-1) | Sends transactional email with SES and stores inbound mail attachments in S3. | Email delivery & storage | Required |
| FastSpring | United States | Processes subscriptions, payments, and related tax collection. | Payment processor | Required |
| Freshdesk (Freshworks) | United States | Provides helpdesk ticketing, embedded contact forms, and knowledge base hosting. | Customer support | Required |
| Drip | United States | Sends lifecycle communications and manages marketing subscribers. | Email marketing | Required |
| Sentry | United States | Captures application errors and performance telemetry for reliability. | Error monitoring | Required |
| ipapi (APILayer) | European Union | Supplies IP geolocation used to determine EU residency for GDPR consent flows. | Geolocation compliance | Required |
| Google Marketing Platform (Analytics, Ads, Tag Manager) | United States | Measures website usage and advertising conversions when visitors grant consent. | Analytics & marketing | Optional |
| Google Fonts | United States | Delivers hosted web fonts for the public marketing site. | Font hosting | Required |
| Zapier | United States | Enables customer-configured automations that connect BillBjorn to other apps. | Automation platform | Optional |
| Intuit QuickBooks Online | United States | Customer-enabled accounting integration and OAuth single sign-on. | Accounting integration | Optional |
| Xero | New Zealand | Customer-enabled accounting integration and OAuth single sign-on. | Accounting integration | Optional |
| Sage Accounting | United Kingdom | Customer-enabled accounting integration. | Accounting integration | Optional |
| MYOB Business | Australia | Customer-enabled accounting integration. | Accounting integration | Optional |
| FreshBooks | Canada | Customer-enabled accounting integration and OAuth single sign-on. | Accounting integration | Optional |