The "Buy vs. Build" debate is the perennial dilemma of the CTO. But in 2024, the variables in the equation have fundamentally shifted.
Ten years ago, "building" meant a team of engineers and six months. Today, with low-code tools, AI copilots, and serverless infrastructure, "building" might take a weekend. Conversely, "buying" used to mean rigid enterprise software. Now, SaaS APIs are so composable they feel like building blocks.
So how do we decide?
The Core Competency Test
The golden rule remains: Build your differentiator, buy your utility.
If a capability is central to your competitive advantage—the thing that makes customers choose you over option B—you must own it. You need to control the roadmap, the data, and the experience.
If it's a utility (payroll, authentication, email delivery, CRM), buying is almost always the answer. Even if you can build a better email server, you shouldn't. It doesn't make the boat go faster.
The Cost of Integration
The hidden killer in "Buy" decisions is integration cost.
Vendors promise "plug-and-play," but the reality is "plug-and-debug." The data models never quite match. The webhooks are flaky. Suddenly, you have three engineers maintaining the "glue code" between five different SaaS tools.
Sometimes, building a simple version is cheaper than integrating a complex one.
The "Build" Premium in the AI Era
AI has lowered the barrier to building. A specialized internal tool that used to require a dedicated frontend dev and backend dev can now be scaffolded by one engineer and an LLM in a day.
This shifts the needle slightly towards "Build" for internal tools.
- Then: Buy Salesforce because building a CRM is madness.
- Now: Build a lightweight CRM in Airtable + Next.js because Salesforce is overkill and we only need 10% of the features.
The Framework
When facing a decision, score it on these three axes:
- Strategic Value: Is this our secret sauce? (High = Build)
- Market Maturity: Are there 50 great vendors solving this? (High = Buy)
- Complexity relative to value: Is the problem harder than it looks? (High = Buy)
The best companies are hybrids. They buy the commodity rails—payments (Stripe), comms (Twilio), hosting (Vercel)—and pour every ounce of engineering energy into the unique logic that defines their business.