Real-time
Two-way sync
Changes in Bill or Kustomer instantly reflect in both systems. No stale data, no manual imports.
Accounting and finance ⇄ CRM
Bill to Kustomer integration — real-time, two-way sync
Keep Bill and Kustomer in sync without custom scripts. Cut weeks of integration work, eliminate silent data drift, and give your team a single, reliable source of truth.
- SOC 2 and 6 other compliance frameworks
- POC with real engineers in minutes
Adopted by fast-scaling companies moving mission-critical data in real time
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Migrated from MuleSoft
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Migrated from Celigo
Migrated from Heroku Connect
Migrated from Matillion
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Migrated from Fivetran
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Migrated from Celigo
Why teams connect Bill and Kustomer
Sync customers, invoices, and payment status between Bill and Kustomer in real time, so sales sees the money and finance sees the relationship.
Finance and sales describe the same customers in different systems. Kustomer knows the relationship: who the contacts are and what is in motion with the account. Bill knows the money: what was invoiced, what was paid, what is overdue. When the two are connected only by exports, each side works partly blind.
Stacksync links Vendor Credits and Credit Memos, Bills, Vendors, Invoices in Bill to Notes, Customers, Conversations, Messages in Kustomer with bi-directional, real-time sync. New customers, updated billing details, invoice status, and payment activity move in whichever direction you configure, field by field, with conflicts resolved by rules you set. The result is one version of each customer, visible from both sides.
Common use cases
- 01 Read Payments and payment status into a reconciliation database once bills are marked paid in BILL.
- 02 Read approved Bills and their line items into a Postgres warehouse for spend, accrual, and cash-flow reporting without CSV exports.
- 03 Escalate conversation-derived signals into the CRM as tasks or opportunities
- 04 Sync customers bi-directionally with the CRM and ERP so agents see deal, billing, and subscription context on the timeline
Common sync patterns
Where Kustomer tracks deals: closed-won creates the finance record
A won opportunity creates or updates the customer in Bill with the right billing details, so invoicing starts without re-keying.
Payment status on the account
Invoice and payment status from Bill appears on the account in Kustomer, so reps see overdue balances before they promise the next order.
Billing detail changes flow back
When a contact or address is corrected in Kustomer, Bill gets the update before the next invoice goes out.
What you can sync between Bill and Kustomer
Representative objects on each side — any object or custom field can map to any target. Schemas are auto-detected; types are converted between the two systems.
| Bill objects | Kustomer objects | How this pairing syncs | |
|---|---|---|---|
| Customers AR customer master records; mapped to customer/account records in a CRM or ERP so finance and sales share one view. | Customers The central record whose timeline aggregates every interaction; external attributes sync onto it. | Same entity on both sides — records pair one-to-one and field-level changes reconcile in both directions. Custom fields on either side are included in the mapping. | |
| Bills Accounts-payable amounts owed to vendors, with bill line items; read and created via /v3/bills and pulled incrementally by filtering on createdTime/updatedTime. | Messages Individual messages within conversations support full-thread replication. | Bills is specific to Bill and Messages to Kustomer — each maps to any object or custom field on the other side. | |
| Vendors Payee master records; synced two-way with vendor/supplier tables in an ERP or accounting system so new payees don't have to be re-keyed. | Companies Organization records group customers and map to CRM accounts. | Vendors is specific to Bill and Companies to Kustomer — each maps to any object or custom field on the other side. | |
| Invoices Accounts-receivable invoices sent to customers; created and read via /v3/invoices to keep billing status aligned with the ERP or CRM. | Custom Objects (Klasses) Structured external records such as orders and subscriptions synced in to appear on the customer timeline. | Invoices is specific to Bill and Custom Objects (Klasses) to Kustomer — each maps to any object or custom field on the other side. | |
| Payments Outgoing vendor payments and received customer payments; read for reconciliation and created to schedule bill pay. | Users Agent records map conversation ownership to people in other systems. | Payments is specific to Bill and Users to Kustomer — each maps to any object or custom field on the other side. | |
| Chart of Accounts GL accounts used to code bills and invoices; typically mastered in the accounting system and written into BILL for consistent coding. | Teams Team assignments support routing parity and reporting. | Chart of Accounts is specific to Bill and Teams to Kustomer — each maps to any object or custom field on the other side. |
How changes propagate between Bill and Kustomer
Each direction of the sync is driven by what the source system can signal and what the destination accepts — detection, delivery, and expected latency below.
Bill Kustomer Sub-second propagation
DetectionBill notifies Stacksync of record changes through webhook events. Webhook event subscriptions (POST /v3/subscriptions) for bills, vendors, payments, invoices, and bank accounts, with polling on.
DeliveryEach detected change is written to Kustomer through its API, with automatic retries and rate-limit backoff.
Kustomer Bill Sub-second propagation
DetectionKustomer notifies Stacksync of record changes through webhook events. Outbound webhooks on record events, plus polling for backfill.
DeliveryEach detected change is written to Bill through its API, with automatic retries and rate-limit backoff.
Rate-limit considerations
- Bill: 20,000 requests per developer key per hour; login (POST /v3/login) capped at 200/hour; maximum 3 concurrent requests per developer key per organization. Spend & Expense API is a separate token at 60 calls/token/minute.
- Kustomer: Subject to the platform's API rate limits.
What ships with Bill ⇄ Kustomer
Connect Bill and Kustomer for flexible, real-time data sync.
Real-time sync, workflow automation, event queues, EDI, and monitoring, for every Bill–Kustomer connection.
No-code + pro-code
Workflow automation
Trigger automated workflows whenever Bill or Kustomer data changes, update records, fire webhooks, or kick off sequences without brittle API scripts.
At scale
Event queues
Handle millions of events per minute without losing a single Bill or Kustomer record.
Observability
Monitoring
Track your Bill ⇄ Kustomer sync health, view errors, and replay failed events in one click.
Trading partners
EDI
Transform legacy EDI complexity into simple database interactions between Bill and Kustomer.
How the Bill and Kustomer connectors work
Bill
- Integration surface
- REST/JSON (BILL v3 Connect API)
- Authentication
- Session-based: POST /v3/login with username, password, organizationId, and a developer key (devKey) returns a sessionId that is passed with the devKey as headers on every subsequent call; OAuth is available for partner/embedded apps
- Change detection
- Webhook event subscriptions (POST /v3/subscriptions) for bills, vendors, payments, invoices, and bank accounts, with polling on createdTime/updatedTime list filters as the fallback
- Capabilities
- read · write · webhooks
- Rate limits
- 20,000 requests per developer key per hour; login (POST /v3/login) capped at 200/hour; maximum 3 concurrent requests per developer key per organization. Spend & Expense API is a separate token at 60 calls/token/minute.
Kustomer
- Integration surface
- REST API
- Authentication
- API key used as a bearer token, scoped by role
- Change detection
- Outbound webhooks on record events, plus polling for backfill
- Capabilities
- read · write · webhooks
- Rate limits
- Subject to the platform's API rate limits
How it works
How to connect Bill to Kustomer — three steps, no code
Configure and sync within minutes, no code. Whether you sync 50k or 100M+ records, Stacksync handles the queues, infra, and plumbing. Integrations are non-invasive and need zero setup on your systems.
- 01
Connect your apps
Authenticate Bill and Kustomer with each platform's native method — OAuth, API keys, or service accounts — plus secure options like SSH tunneling, IP whitelisting, and VPC peering.
Bill
connected
Kustomer
connected
OAuth 2.0SSH tunnelSSL certificateVPC peering - 02
Choose tables
Pick the Bill and Kustomer objects to sync — Stacksync auto-detects both schemas, including custom fields where the platform exposes them. Sync to existing tables, or let Stacksync create new ones with ideal data types.
objects · Bill ⇄ KustomerCustomers 12,480Sales Orders 8,213Invoices 5,902Items 1,344 - 03
Map fields
Fields map automatically even when names and types differ. Stacksync handles transformation and type casting for you, zero configuration required.
Bill KustomerCompany company_name textEmail email textAmount amount numericCreated created_at timestamp
FAQ
Bill and Kustomer integration FAQ
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Yes. Stacksync provides a managed, real-time two-way integration between Bill and Kustomer: authenticate both systems, choose the objects to sync (such as Bill's Customers and Bills), map fields visually, and changes propagate both ways in milliseconds — no code required.
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Stacksync is SOC 2 Type II and ISO 27001 certified with HIPAA BAA support. Data is encrypted in transit, and a zero-persistent-storage architecture means Bill and Kustomer records are not retained after a sync operation.
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Stacksync pricing is usage-based and starts at $1,000/month, including the managed Bill and Kustomer connectors, real-time two-way sync, monitoring, and support. That replaces building and maintaining a custom Bill–Kustomer integration in-house.
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Yes — Stacksync ships production-grade connectors for both Bill and Kustomer. The connectors handle authentication, schema detection, rate limits, and retries; you configure the sync, and Stacksync operates it.
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Change detection on Bill: Webhook event subscriptions (POST /v3/subscriptions) for bills, vendors, payments, invoices, and bank accounts, with polling on createdTime/updatedTime list filters as the fallback. On Kustomer: Outbound webhooks on record events, plus polling for backfill. Each detected change propagates to the other side in milliseconds, with field-level conflict resolution and an inspectable event log.
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On the Bill side: Vendor Credits and Credit Memos, Bills, Vendors, Invoices, plus custom fields where Bill exposes them. On the Kustomer side: Notes, Customers, Conversations, Messages. Stacksync auto-detects both schemas and converts types between the two systems.
SECURITY
Security teams trust Stacksync
As a data company, we understand the importance of keeping your data secure. Stacksync is built with security best practices to keep your data safe at every layer, and is DPF-certified for US, EU, UK and CH data transfers.
SOC 2 Type II
ISO 27001
HIPAA BAA
GDPR
CCPA
CSA STAR
DPF US-EU-UK-CH
→ SECURITY WITH BENEFITS
SSO & SCIM
Let your users access Stacksync from your centralized user management systems. Works with Okta, Azure, Google SSO and more.
Alerts
Immediately get alerted about record syncing issues over email, Slack, PagerDuty and WhatsApp. Resolve issues from a centralized dashboard with retry and revert options.
Secure connection options
Securely connects to your systems with:
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