For decades, companies opted to buy software instead of building it. The complexity, cost and time required to develop internal tools made off-the-shelf solutions the default choice.

These monolithic platforms bundled tools, workflows and data, but came with hidden costs: rigid systems, vendor lock-in and escalating expenses as businesses grew. Even when companies bought software, they ended up building on top of it, but on foundations they don’t own.

Today, the landscape has shifted. Advances in composable building blocks, vertical SaaS and AI coding tools have made it easier and more affordable than ever to build custom solutions tailored to unique business needs.

Software-as-a-Block

The software industry is seeing the emergence of a new category of tools: companies that package state-of-the-art infrastructure into elegant, composable APIs. Unlike traditional SaaS, these are modular building blocks designed to fuel larger systems:

• Payments: Stripe, Plaid
• Communication: Resend, Knock
• Workflows: Trigger.dev, Inngest
• Authentication: Clerk, WorkOS
• Data: Xata, Flatfile
• Backend: Supabase, Convex

These API-first tools democratize access to enterprise-grade infrastructure. Initially targeting developers, their composable nature makes them perfect for internal tooling. Companies can now build systems using proven, reliable components without the overhead of traditional development.

Vertical SaaS

Another new wave of SaaS has gained cult-like followings in recent years due to their extreme vertical focus and relentless pursuit of crafting magical products for their core customer segment: Linear, Ramp, Fillout and Attio.

These tools prioritize:

• Focused excellence: Solving one problem exceptionally well, rather than trying to own entire work streams.
• API-centricity: Built to be inherently composable, designed to work effortlessly with other blocks.
• Cost-efficiency: Usage-based pricing that scales with value rather than headcount.
• Customer obsession: Great customer experience end-to-end, especially documentation and customer support.

Vertical SaaS tools excel in their domain and embrace composability, instead of trying to expand horizontally by becoming a suite of tools. Custom systems can now be built from proven, reliable components—eliminating the need to settle for the limitations of all-in-one platforms.

AI Coding Tools

The other big shift is the advent of LLMs and AI coding tools:

• IDEs: Cursor, Replit, Windsurf
• Agents: Devin, Exponent
• Coding chatbots: Lovable, bolt.new
• Code review: CodeRabbit, Korbit
• Specialized coding chatbots: v0, database.new

These extraordinary tools are rapidly expanding what's possible to build using natural language and logical thinking. The pace of improvement is staggering. Features that seemed like science fiction six months ago are now routine. As these tools mature, the cost of writing and maintaining code will virtually disappear.

In many ways, AI coding tools are building upon the groundwork laid by the no-code/low-code movement. That first wave showed business teams they didn't need to wait for engineering bandwidth to build software solutions to their operational problems. What AI has done is exponentially expand the scope of what these teams can now build: from simple automations to full-fledged custom systems.

The Recipe for Modern Operational Systems

The convergence of Software-as-a-Block, vertical SaaS and AI coding tools enables a new approach to building operational systems:

1. Start with the data layer: Build a unified foundation that serves as your single source of truth. Tools like Xata and Supabase make this easier than ever.
2. Compose best-in-class building blocks: Cherry-pick the best tools for each specific need—Stripe for payments, Resend for communications, Linear for product management—each excellent at what it does.
3. Build custom workflows: Use code and AI tools to connect these blocks, creating workflows tailored to your exact needs.
4. Create custom interfaces: Design purpose-built views and tools for specific use cases, ranging from simple dashboards to complex operational tools, powered by your unified data layer.

The result? A system combining the reliability of proven components with the flexibility of custom software—without the traditional costs and complexity.

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Ready to build unique internal tooling for your company? Reach out at hello@railblocks.co.