Build vs. Buy: The True Cost of Building SaaS Integrations In-House

You just lost a six-figure enterprise deal because your app doesn't sync with Salesforce. The immediate reaction from engineering is predictable: "Give me a week. It’s just a few REST API calls."

Fast forward six months. That single integration has spawned a dedicated sub-team. Your error logs are choked with 401 Unauthorized and 429 Too Many Requests errors. The platform you integrated with just deprecated their v2 API, forcing a complete rewrite. And the sales team? They just asked for 49 more integrations.

Build vs. buy for SaaS integrations is the strategic decision between dedicating internal engineering resources to write and maintain custom API connections (build) or purchasing a third-party Unified API to handle the infrastructure (buy).

In this post, we are breaking down the true costs of building integrations in-house, looking at the actual math, and providing an honest pros and cons comparison so you can make the right architectural decision for your team.

The "Just a Few API Calls" Trap

When product teams estimate the time required to build an integration, they look at the API documentation, find the endpoints they need, and estimate the time to write the HTTP requests.

This is the integration iceberg. The HTTP request is the 10% visible above the water. The remaining 90%—authentication, pagination, rate limiting, data normalization, webhooks, and ongoing maintenance—lurks below the surface, ready to sink your product roadmap.

Let's look at exactly what lives beneath the surface.

The Hidden Costs of Building In-House

1. Data Normalization and Pagination

Building an integration isn't just moving JSON from point A to point B. Every SaaS platform structures data differently. What you call a "User," Salesforce calls a "Contact," Zendesk calls a "Requester," and Jira calls an "Assignee." Your team has to write custom mapping logic for every single platform.

Pagination is equally messy. Some APIs use cursor-based pagination, others use offset-based pagination, and some rely on page numbers. Your engineering team must build custom abstraction layers to handle these discrepancies.

2. OAuth Management and Race Conditions

Authentication is the most fragile part of any integration. Most modern SaaS applications use OAuth 2.0, requiring a complex dance of authorization codes, access tokens, and refresh tokens.

The real headache begins with token expiration. Access tokens expire frequently. Your system needs to intercept 401 Unauthorized errors, pause the current job, use the refresh token to get a new access token, update your database, and retry the original request.

If you have multiple background workers trying to sync data simultaneously and a token expires, you hit a race condition. Multiple workers try to refresh the token at the same time, the API provider invalidates all tokens, and your customer is forced to manually re-authenticate.

3. Rate Limits and Exponential Backoff

No SaaS platform lets you pull data at unlimited speeds. They protect their infrastructure using rate limits, and every platform enforces them differently:

• Shopify uses a leaky bucket algorithm.
• HubSpot limits requests per second and per day.
• Salesforce limits concurrent API requests.

When you hit a limit, the API returns a 429 Too Many Requests error. A naive integration will simply crash or drop the data. A production-grade integration requires implementing exponential backoff and retry queues. You have to parse the Retry-After headers (which are formatted differently by every provider), pause your workers, and safely resume later without losing data.

Here is a look at the boilerplate code required just to safely make a request in-house versus using Truto.

# The In-House Way: Handling Auth, Retries, and Pagination
import time
import requests
 
def fetch_data_safely(url, tenant_id):
    max_retries = 5
    for attempt in range(max_retries):
        token = get_valid_token_from_db(tenant_id) # Custom logic with DB locks
        headers = {"Authorization": f"Bearer {token}"}
        
        response = requests.get(url, headers=headers)
        
        if response.status_code == 200:
            return response.json()
            
        elif response.status_code == 401:
            refresh_oauth_token(tenant_id) # Handle race conditions here
            continue
            
        elif response.status_code == 429:
            retry_after = int(response.headers.get("Retry-After", 2 ** attempt))
            time.sleep(retry_after) # Blocks the worker thread
            continue
            
        else:
            raise Exception(f"API Error: {response.status_code}")
            
    raise Exception("Max retries exceeded")

# The Truto Way: Unified API handles everything
import requests
 
def fetch_data_with_truto(tenant_id):
    # Authentication, rate limits, and retries are handled automatically
    headers = {"Authorization": f"Bearer {TRUTO_API_KEY}", "X-Tenant-Id": tenant_id}
    response = requests.get("https://api.truto.one/unified/crm/contacts", headers=headers)
    return response.json()

4. API Versioning and Silent Breakages

APIs are living organisms. Providers constantly add new features, change data types, and deprecate old endpoints.

If you build integrations in-house, you are committing to infinite maintenance. Your engineering team must monitor changelogs and schedule refactoring sprints whenever an API version is deprecated. If you miss a deprecation notice, the integration breaks silently in production. You usually find out when an angry customer submits a support ticket.

Pros and Cons of Building In-House

Let's be honest: building in-house isn't always the wrong choice. It depends entirely on your use case.

Pros of Building In-House:

• Total Control: You own the entire data pipeline end-to-end.
• Deep, Niche Access: If you need to access highly obscure, undocumented endpoints that a unified API provider hasn't mapped yet, building natively gives you that access.
• No Vendor Reliance: You aren't dependent on a third-party middleware provider's uptime (other than the end SaaS platform itself).

Cons of Building In-House:

• Massive Engineering Drain: Your best engineers spend their time reading third-party API docs instead of building your core product.
• High Maintenance Debt: Every integration you build is a permanent tax on your engineering team's future velocity.
• Infrastructure Costs: Building polling infrastructure, dead-letter queues, and worker nodes drives up your AWS/GCP bills.

Showing the Math: The True Cost of In-House Integrations

Let's look at the actual numbers. We'll assume a conservative blended rate of $100/hour for a mid-level software engineer.

The Cost of 1 Integration

• Initial Build: 40 hours = $4,000
• Maintenance (API updates, bug fixes, monitoring): 10 hours/month = 120 hours/year = $12,000/year
• Total Year 1 Cost: $16,000

Spending $16,000 to unblock a massive enterprise deal makes sense. But SaaS products rarely need just one integration.

The Cost of 50 Integrations

To be competitive in categories like HR, CRM, or ticketing, you often need to offer dozens of integrations.

• Initial Build (50 x 40h): 2,000 hours = $200,000
• Maintenance (50 x 120h): 6,000 hours/year = $600,000/year
• Total Year 1 Cost: $800,000

At 50 integrations, you have accidentally built an entire integration company inside your own startup. You are dedicating three full-time engineers purely to maintaining third-party APIs.

The Buy Alternative: Unified APIs

The "Build vs. Buy" debate used to mean choosing between writing custom code or forcing your customers to use clunky third-party tools like Zapier. Today, the solution is the Unified API.

A Unified API normalizes data across hundreds of SaaS platforms into common data models. Instead of building 50 different integrations, your engineering team builds one integration against the Unified API.

Pros and Cons of Buying a Unified API

Pros of Buying:

• Speed to Market: Build one integration and instantly offer your customers dozens of platforms (Salesforce, HubSpot, Zendesk, etc.).
• Zero Maintenance: When an underlying API changes or deprecates an endpoint, the Unified API provider updates the connector. Your code never changes.
• Automated Infrastructure: Authentication, token refreshes, rate limits, and pagination are handled out of the box.

Cons of Buying:

• Vendor Reliance: You are adding a dependency to your stack. If the Unified API provider goes down, your integrations go down. (This is why choosing a provider with enterprise-grade SLAs and fail-safe architecture is critical).
• Abstraction Limits: Unified models cover 95% of use cases, but if you need highly specific, non-standard data, you might feel restricted. Note: Premium providers like Truto solve this by offering "passthrough" requests, allowing you to hit native endpoints directly through their auth proxy when needed.

The Verdict: When to Build vs. When to Buy

So, which route should you take?

Build in-house if:

• You only ever plan to integrate with one or two specific platforms.
• The integration requires deep, highly specialized functionality that falls completely outside standard data models (e.g., executing complex, multi-step proprietary workflows inside a legacy ERP).
• Your core product is an integration platform.

Buy a Unified API if:

• You need to integrate with a category of tools (e.g., "We need to integrate with all CRMs" or "We need to pull data from all HRIS platforms").
• You want to ship integrations in days, not months.
• You are tired of your engineering team acting as a maintenance crew for third-party APIs.

Your company's competitive advantage is your core product, not your ability to parse Salesforce's SOAP API or manage HubSpot's OAuth tokens. By leveraging a unified API, you can offer your customers the connectivity they demand while keeping your engineering team focused on what they do best.