--- title: "Build vs. Buy Has Flipped: Custom AI-Built Tools vs SaaS" description: "AI coding agents made custom internal software cheap. When building beats another SaaS subscription, and when it turns into a maintenance trap." url: https://axiointelligence.com/blog/build_vs_buy_has_flipped --- [← Blog](https://axiointelligence.com/blog) build vs buy, AI coding agents, fractional CTO, SaaS # Build vs. buy has flipped: when custom AI-built tools beat SaaS Brice Ayres / October 11, 2026 Short answer Agentic coding tools cut the cost of building small internal tools from weeks to days, and McKinsey's 2026 survey finds 32% of organizations have already skipped at least one software purchase because they could build it. Build when the workflow is yours, the scope is small and you're paying for glue or per-seat sprawl. Buy anything regulated, security-critical or full of edge cases. Either way, someone technical has to own what you build. For years the build-vs-buy answer for a small company was boring: buy. Unless the software *was* your product, writing your own CRM, scheduler, or reporting dashboard was a great way to burn six months and end up with something worse than a $49/month tool. That math has changed, and not just for us. McKinsey’s *State of AI in 2026* survey found that **32% of respondents say their organizations decided against buying at least one software product or feature because they could build it in-house with agentic coding tools**. In tech it’s 41%. Healthcare is 39%. Professional services is 38%. ([McKinsey, The state of AI in 2026](https://beszerzes.hu/wp-content/uploads/2026/09/The-state-of-AI-in-2026-On-the-road-to-ROI-.pdf)) That’s a third of companies saying “we’ll build that ourselves.” It lines up with what we’re seeing with clients. ## What actually changed Coding agents didn’t make software engineering free. They made the *first 80%* dramatically cheaper. A focused internal tool (an intake form that writes to your database, a dashboard that joins three spreadsheets, a script that reconciles invoices) used to be a few weeks of work. Now it’s often a few days, sometimes an afternoon. When the build cost drops that much, a lot of SaaS stops making sense. Especially the kind you’re paying per-seat for while using 10% of the features. ## When we tell clients to build - **The workflow is yours, not generic.** If you’ve spent months bending a tool to fit how your business actually works, that’s the signal. Custom software that matches your process is a real advantage. - **The scope is small and stable.** Internal tools with a handful of users and clear inputs and outputs are the sweet spot. - **You’re paying for glue.** A lot of SaaS spend is really just moving data between other SaaS. That’s exactly what agents are good at writing. - **Per-seat pricing is eating you.** If a tool costs more every time you hire, run the numbers on a one-time build. ## When we still tell clients to buy - **Anything regulated or security-critical.** Auth, payments, payroll, compliance. Pay someone whose entire job is getting that right. - **Things with a long tail of edge cases.** Email deliverability, accounting, tax. The demo is easy; year three isn’t. - **When nobody will own it.** This is the big one. ## The catch nobody puts in the demo Building got cheap. *Owning* didn’t. Every tool you build is a tool you maintain: dependency updates, API changes, the one person who knows how it works going on vacation. AI-generated code makes this worse if nobody reviews it. You can end up with a pile of working-but-mysterious scripts that nobody wants to touch. Our rules for keeping custom tools from becoming a liability: 1. **Someone technical owns it.** An employee, a contractor, or a fractional CTO, but a name, not “the AI.” 2. **It lives in a repo with tests.** Even a few. Agents are great at writing tests if you ask. 3. **Keep it boring.** Mainstream languages, managed hosting, no clever infrastructure. 4. **Write down the exit.** If this thing breaks and we can’t fix it, what do we buy instead? ## How to decide this week Pull up your software subscriptions. For each one, ask: - Do we use more than a third of it? - Does it match how we actually work? - What would a simple version we own cost to build *and* maintain for two years? You’ll probably find one or two tools where building wins clearly. Start there, keep it small, and treat it like real software. If you want a second opinion on which ones are worth building, that’s exactly the kind of call we help with at Axio Intelligence. [Book a call](https://axiointelligence.com/book). ## We do this work for a living. A 30-minute scoping call with the engineers who would do the work. [Book a scoping call](https://axiointelligence.com/book) Or email [contact@axiointelligence.com](mailto:contact@axiointelligence.com?subject=Project%20inquiry) and we’ll reply. ## Related posts Oct 11, 2026 ### [DHH's Campfire shootout, part 2: the Elixir port played by different rules](https://axiointelligence.com/blog/dhh_campfire_shootout_part_2) The Campfire repos show Rust could drop Redis and diverge from Rails while Elixir PRs doing the same were turned down. What a fair benchmark needs. Elixir, Rust, benchmarks Oct 6, 2026 ### [398 commits vs 2: how to run a fair language benchmark with AI-written code](https://axiointelligence.com/blog/fair_language_benchmark) The Campfire Rust port had about 400 commits before the benchmark. The Elixir port had two. How to run a fair benchmark when AI agents write the code. benchmarks, Rust, Elixir Oct 4, 2026 ### [DHH's Campfire shootout: AI agents rewrote one app in Rust, Go and Elixir](https://axiointelligence.com/blog/dhh_campfire_shootout) DHH had AI agents port Campfire from Rails to Rust, Go and Elixir and found Rust fastest. What he actually claimed, and why it's worth taking seriously. Rust, Elixir, AI coding agents