How Much to Pay for Custom API Development and Integrations
A small business can expect a custom API integration to take 2 to 4 weeks for a complete build. A more complex project connecting multiple legacy systems may require up to 6 weeks for development and deployment.
Project scope depends on the quality of API documentation and the complexity of the data transformations required. Connecting two modern platforms with well-documented REST APIs is straightforward. Integrating a proprietary ERP with a SOAP API and a CRM requires more extensive mapping and error handling logic.
We recently built a document processing pipeline for a 12-person recruiting firm. They connected their applicant tracking system to an internal HR database. The 3-week build now processes 400 applicant resumes a month, reducing a 6-minute manual data entry task to an 8-second automated workflow.
What Problem Does This Solve?
Many businesses first attempt integrations using the built-in connectors within their SaaS tools. A CRM's native webhook might send a JSON payload to a URL, but it offers no built-in retry logic. If the receiving endpoint is down for 30 seconds, that customer data is lost permanently without a trace.
Next, teams turn to visual, point-and-click automation platforms. These tools are excellent for simple IFTTT (if this, then that) logic but fail with complex business rules. A workflow that needs to check inventory in one system, verify customer credit in another, and then apply volume-based discounts before creating an invoice becomes a tangled web of paths. These platforms often cannot merge branched paths, forcing you to duplicate logic and double your task usage for a single transaction.
A regional insurance agency with 6 adjusters faced this exact issue. They needed to sync data from a claims management system to their accounting software. The platform they used could not handle the token-based authentication of the claims API. It also timed out on batch jobs of more than 100 records, forcing them to run manual exports every afternoon, defeating the purpose of automation.
How Does It Work?
Our process starts by mapping every required data field and transformation rule in a shared document. For the insurance agency, this meant defining how 25 distinct fields from their claims system (like `policy_id` and `loss_date`) mapped to the 12 fields in their accounting software's API. This specification becomes the blueprint for the build.
We then write the core logic in Python, using the FastAPI framework to create a lightweight API service. We use httpx for its robust support for async requests and configurable retry mechanisms, ensuring that temporary downtime from an external API does not cause data loss. All sensitive credentials, like API keys, are managed through AWS Secrets Manager, never hard-coded.
The service is deployed as a serverless function using AWS Lambda, which costs nothing when idle. For the agency processing 200 claims per week, the total monthly hosting cost on Lambda is under $30. We use Supabase, a Postgres-based database, to log every transaction and its outcome. This provides a complete audit trail and makes debugging any single failed sync take minutes, not hours of searching through platform logs.
Finally, we configure monitoring using Amazon CloudWatch. We set up alerts that trigger on two conditions: an error rate exceeding 1% over a 5-minute window, or a processing latency greater than 500ms. These alerts post directly to a shared Slack channel, so any production issue is visible to both of us instantly. The final system processes each new claim in under 150ms.
What Are the Key Benefits?
Launch in Weeks, Not Quarters
Your custom integration is live in 2-4 weeks. We scope tightly and build efficiently, so you see the return on investment before the next billing cycle.
One Fixed Price, No Surprise Bills
We quote a single, fixed price for the entire scoped build. After launch, you only pay for cloud hosting, with no per-user or per-task fees.
You Own The Code and Infrastructure
We deliver the complete Python source code to your company's GitHub account and deploy it on your own AWS infrastructure. There is zero vendor lock-in.
Built-in Monitoring from Day One
Your system includes structured logging with structlog and automated CloudWatch alerts for errors and latency spikes. We catch problems before they impact your business.
Connects to Any Modern or Legacy API
We build connectors for REST, GraphQL, and SOAP APIs. We also handle older systems that rely on FTP data drops or direct database connections.
What Does the Process Look Like?
Scoping and Access (Week 1)
You provide API documentation and read-only credentials for the systems you want to connect. We deliver a detailed technical specification and a fixed-price proposal.
Core System Build (Weeks 1-2)
We write the Python code for data transformation and API communication. You receive access to a private GitHub repository to review progress and code quality.
Deployment and Testing (Week 3)
We deploy the system to a staging environment on your cloud infrastructure for user acceptance testing. You receive a list of test cases to validate functionality.
Handoff and Monitoring (Week 4)
After a successful test, we deploy to production. You receive a runbook with architectural diagrams and instructions for maintenance. The optional support plan begins.
Frequently Asked Questions
- What factors most influence the project cost and timeline?
- The primary factors are the quality of API documentation and the number of systems being connected. A project with clear, modern REST API docs for two systems is typically a 2-week build. A project involving an undocumented, legacy SOAP API or connecting three or more systems is more likely to take 4 weeks due to the added complexity in discovery and testing.
- What happens if an external API your system relies on goes down?
- The system is designed for this. Using AWS Lambda and SQS, a failed API call is automatically placed in a dead-letter queue. The system then retries the call with exponential backoff for up to 24 hours. If it still fails, a notification is sent with the exact request data, so it can be replayed manually once the external service is restored. No data is ever lost.
- How is this different from hiring a freelancer on Upwork?
- We deliver production-ready systems, not just scripts. This includes deployment on your infrastructure, comprehensive logging, automated monitoring and alerting, and a detailed runbook for future maintenance. The engagement model is a scoped project with a clear deliverable, not an hourly contract. The person you talk to on the discovery call is the engineer who writes every line of code.
- How is our sensitive data and API keys handled?
- All development and deployment happens within your own cloud environment (e.g., your AWS account). We never store your data or credentials on Syntora's systems. Sensitive keys are stored securely using AWS Secrets Manager or a similar service, and accessed at runtime with IAM roles. You retain full control and ownership of your data and infrastructure at all times.
- We have an old system with no API. Can you still integrate it?
- Often, yes. If the system uses a standard database like Postgres, MySQL, or SQL Server, we can connect to a read-only replica to extract data. For systems that can only perform scheduled file exports (like CSV or XML files to an FTP server), we can build a process that watches for new files and ingests them as they arrive. This is a common pattern for legacy ERP and accounting systems.
- What does the optional monthly maintenance plan include?
- The maintenance plan covers proactive monitoring of API uptime and performance, regular updates to libraries and dependencies to patch security vulnerabilities, and 2 business hours of support per month for minor changes or troubleshooting. It ensures the system remains secure and functional as the underlying platforms and libraries evolve. The cost is a flat monthly fee.
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