Integrate Your Accounting, CRM, and Payment Systems
Yes, a custom API can integrate your accounting software, CRM, and payment gateways. It provides a direct, real-time connection that off-the-shelf tools cannot match.
The complexity of the build depends on the specific systems and the required business logic. A standard integration connecting QuickBooks Online, Salesforce, and Stripe is a common pattern. Connecting a legacy, on-premise ERP with limited API documentation requires a more extensive discovery phase to map the data models correctly.
We built an integration for a 25-person services firm connecting their QuickBooks Online, Salesforce, and Stripe accounts. The build took 3 weeks and reduced their monthly financial close process from 4 days to under 2 hours by completely automating invoice reconciliation.
What Problem Does This Solve?
Most teams start with native sync apps, like the QuickBooks connector in the Salesforce AppExchange. These work for basic use cases but fail with custom fields. If your Salesforce Opportunity has a custom 'Project ID' required for job costing in QuickBooks, the native sync ignores it, forcing your finance team to manually copy and paste the ID for every single invoice.
A common next step is a multi-step workflow in a no-code tool. This approach is brittle. A workflow might create a customer in Stripe and then an invoice in QuickBooks. If the QuickBooks API is temporarily down and that step fails, you now have a paying customer in Stripe with no corresponding accounting record. There is no automatic rollback, creating data integrity issues that are only discovered during a painful month-end audit.
This workflow also becomes expensive. A single new customer might trigger 5 separate tasks: create customer, create subscription, create invoice, update CRM deal, log to a sheet. At 100 new customers per month, that's 500 tasks. As you grow to 1,000 customers, your bill increases tenfold for the exact same workflow, punishing your success.
How Does It Work?
We start by mapping the entire data flow. Using the Python library httpx, we connect to the live APIs for your accounting, CRM, and payment systems to pull the exact data schema. We identify every standard and custom field that must sync, creating a clear data contract that governs the entire build. This plan ensures that critical data like a 'Project ID' is never missed.
We build a central API using FastAPI that acts as the single source of truth for all transactions. When Stripe processes a payment, it sends a webhook to our service. The API validates the event, creates a properly formatted invoice in QuickBooks, and then updates the deal status in your CRM. This entire three-system transaction is atomic and completes in under 800ms.
The FastAPI service is deployed on AWS Lambda, a serverless platform. This architecture is highly efficient, costing less than $20 per month to process over 15,000 transactions. All logs are written as structured JSON using structlog, allowing us to instantly query and diagnose any API error from a third-party system, like a malformed request error from the QuickBooks API.
For reliability, every endpoint is idempotent, meaning duplicate webhooks from Stripe won't create duplicate invoices. If an API call to an external system fails, we implement an exponential backoff retry mechanism that attempts the call 5 times over 10 minutes. If the call still fails, the system sends a detailed alert to a designated Slack channel with the full error payload for immediate investigation.
What Are the Key Benefits?
Transactional Integrity, Guaranteed
A failed QuickBooks invoice automatically prevents the corresponding CRM update. This prevents the mismatched data that corrupts your financial reports and requires hours of manual fixing.
Fixed Build Cost, Near-Zero Runtime
A one-time project fee and serverless hosting costs that stay low, regardless of volume. No per-user or per-task fees that punish you for growing your business.
You Get the Keys and the Blueprints
We deliver the complete Python source code to your company's GitHub account, along with a runbook explaining the architecture and deployment process. No vendor lock-in, ever.
Real-Time Sync in Under a Second
Data moves between your systems in less than 800 milliseconds. Your sales and finance teams see the same correct data, all the time, without waiting for a batch sync to run.
Connects Your Actual Tech Stack
We write direct integrations for your exact systems: HubSpot, Salesforce, QuickBooks, Xero, Stripe, and industry-specific platforms with REST APIs. No compromises from pre-built connectors.
What Does the Process Look Like?
API Audit & Data Mapping (Week 1)
You provide read-only API keys for your systems. We deliver a data flow diagram and a mapping document that details every field being synced, which you approve before the build begins.
Core API Development (Week 2)
We build the central FastAPI service and test all logic against your systems' sandbox environments. You receive a link to a private GitHub repository to view the code and track progress.
Staging Deployment & UAT (Week 3)
We deploy the integration to a staging environment for you to test. You receive a formal test plan with specific scenarios to run, ensuring the logic meets your business requirements.
Go-Live & Monitoring (Week 4)
After your sign-off, we deploy to production. We provide 30 days of active monitoring and support. You receive the final runbook, system documentation, and full ownership of the code.
Frequently Asked Questions
- What determines the cost and timeline?
- The primary factors are the number of systems and the complexity of the business logic. A one-way sync from Stripe to QuickBooks is simpler than a three-way sync with conditional rules for different product SKUs. Systems without modern, well-documented APIs also require more discovery time, which affects the scope. We provide a fixed-price quote after our initial discovery call.
- What happens if QuickBooks changes its API?
- We build against versioned API endpoints to minimize the impact of routine updates. In the case of a major breaking change, our optional monthly maintenance plan covers the code adjustments. Since we own the codebase, these updates are surgical and typically take only a few hours, not a full rebuild. We subscribe to developer changelogs to get ahead of these changes.
- How is this different from an iPaaS like Celigo or Workato?
- iPaaS platforms provide a visual builder and pre-built connectors for an annual subscription fee, which can be very high. We build a single-purpose, code-based asset that you own completely. This approach results in a lower total cost of ownership, higher performance for your specific workflow, and no platform-specific limitations. You are not paying for a thousand features you do not use.
- What if a transaction fails permanently?
- The system is built with a dead-letter queue on AWS. If a transaction fails after all retry attempts, the full request payload is sent to this queue and a high-priority alert is triggered. This means failed syncs are captured for manual review and replay. We know about an issue within minutes, not at the end of the month.
- Can we add another system later, like our ERP?
- Yes. The API is designed with modular connectors. Adding a new system involves writing a new module for that specific API and adding it to the core logic. Since the central infrastructure, error handling, and deployment pipeline are already built, adding a new connection is a much smaller and faster project than the initial integration.
- Do we need an in-house engineer to maintain this?
- No. The AWS Lambda deployment is serverless, requiring no system administration. We provide a runbook that covers common operational tasks like rotating an API key. For any future changes or additions, you can re-engage Syntora for a small, scoped project. Because you own the standard Python code, any competent developer can also take over maintenance.
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