Build vs buy: The real cost of internal development compared to using APIs

When faced with the decision to build a feature in-house or integrate an existing API, many teams underestimate the true cost of building internally. While the idea of owning the codebase and customising every detail is appealing, it often comes with significant upfront and ongoing expenses that far outweigh the cost of using a well-maintained API. Here’s a breakdown of the real costs involved in building internally vs using an API.

Upfront development costs

Building a feature or tool internally requires a considerable investment in time, talent, and planning. From hiring developers to architecting the solution, the initial development phase can take weeks or months depending on complexity.

• Developer salaries: A team of engineers may cost tens of thousands per month to build and test the feature.
• Project management: Coordination, meetings, and roadmaps consume time that could be spent on core product work.
• Tooling and infrastructure: Cloud services, storage, and monitoring tools add setup costs before the product is even launched.

Ongoing maintenance and support

Once a feature is built, it doesn’t maintain itself. Internal tools require constant upkeep—fixing bugs, handling edge cases, updating for security patches, and adapting to evolving requirements.

• Bug fixes and updates: Engineering resources must be allocated for fixing regressions and improving functionality.
• Security patches: Unpatched tools become a liability, requiring dedicated monitoring and updates.
• Downtime and performance: Ensuring uptime, speed, and reliability requires operational support and monitoring infrastructure.

Infrastructure and scaling costs

Scaling an internal solution is not free. As usage grows, so do server costs, storage needs, and bandwidth expenses. More users mean higher expectations for speed and reliability, which require technical investment to meet.

On the other hand, most modern APIs are built to scale. They include rate-limiting, load balancing, and caching at the infrastructure level—without requiring your team to engineer and maintain it.

Opportunity cost of internal builds

Perhaps the most overlooked cost is the opportunity cost. Every week spent building and fixing a non-core feature is time not spent on your primary product differentiators. Especially for startups and lean teams, this can slow growth and product velocity significantly.

APIs offer a plug-and-play alternative that frees your team to focus on your unique value proposition. Instead of building CV parsing or job matching from scratch, for example, platforms like Gateway APIs provide high-performance solutions you can integrate in minutes.

Cost comparison example

Imagine building a CV parsing engine internally:

• Initial development: 2 engineers × 3 months = ~£30,000+
• Infrastructure and storage = £2,000–£5,000/month depending on scale
• Ongoing support: 0.5 FTE for maintenance = ~£3,000/month

Compare that with using Gateway APIs:

• Pay-as-you-go or usage-based pricing
• No infrastructure or maintenance costs
• Instant deployment and best-in-class accuracy

Conclusion

While building internally might seem like a strategic investment, the actual cost—financial, operational, and strategic—can be substantial. APIs are designed to eliminate this burden, providing reliable, scalable, and cost-effective solutions that let your team focus on what truly matters.

Whether you're parsing documents, verifying users, or building intelligent search, Gateway APIs offers a smarter way to deliver value without overextending your resources.