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Custom LLM Application Development

Applications built around a language model as the reasoning engine — not a wrapper around a public chat interface, but software that does a specific job well.

01 The problem

It's easy to wire a public API key into a basic chat interface. It's much harder to build software that reliably does a specific job — summarizing contracts a certain way, classifying support tickets against your internal taxonomy, drafting content in your brand's voice — without drifting, hallucinating, or breaking when the input looks slightly different than expected.

Off-the-shelf AI tools are built for the general case. When your workflow has specific rules, specific data formats, or needs to plug into software you already run, a generic tool usually can't flex far enough, and teams end up stitching together fragile no-code automations that break under real load.

There's also a model-selection problem: different tasks are genuinely better served by different models, and picking one and hard-coding it means re-engineering later when a better or cheaper option ships. Few businesses have the in-house expertise to evaluate that tradeoff correctly, let alone keep re-evaluating it as the field moves.

02 How we solve it

We build the application layer around the model, not the other way around — proper input validation, structured outputs you can rely on downstream, and a model-routing layer so we can swap or mix providers as the field moves without a rewrite.

Every LLM app we build is grounded in your actual data and rules, tested against real examples from your workflow (not toy prompts), and shipped with monitoring so you can see when outputs drift and why.

Because we write the code ourselves rather than assembling third-party no-code blocks, you get software you can extend later — new features are a code change, not a new subscription to a different tool. We also document the prompt and validation logic clearly, so you're not dependent on us for every small adjustment.

03 Sample workflow

What shipping this actually looks like.

01

Define the task precisely

We scope exactly what the model needs to input, output, and get right — vague tasks make unreliable software.

02

Scope + fixed quote

A written scope and firm price based on the real complexity of the task, not a generic estimate.

03

Build with structured outputs

We build validation and structure around the model so downstream systems can trust the output.

04

Test against real examples

We run the app against real data from your workflow, not synthetic test cases.

05

Launch + monitor drift

We ship with monitoring so you can see quality over time, not just at launch.

06

Document + handoff

You get clear documentation of the prompt and validation logic, not a black box only we understand.

Tools we typically useMultiple LLM providers (model-routed by task), Structured output validation, Your existing databases/APIs, Evaluation + monitoring pipelines
TimelineTypical custom LLM apps ship in 2–4 weeks depending on integration complexity.
PricingLLM application builds typically run $3,500–$12,000, depending on how many downstream systems the output needs to feed into.
04 FAQ

Common questions.

Which AI model do you use?

It depends on the task — we route to whichever model performs best for the specific job, and design the system so switching providers later doesn't require a rewrite.

How do you stop the model from making things up?

We ground outputs in your real data, validate structure before anything reaches downstream systems, and build monitoring to catch drift after launch.

Can this replace our current no-code AI tool?

Often yes — a custom build removes the per-seat pricing and rigid limits of no-code platforms once your workflow has outgrown them, and it stops you paying for seats you don't need.

Do you handle the hosting and infrastructure?

We can build on infrastructure you already use or set up hosting as part of the project — either way, you own the deployment.

What if our task changes after launch?

Because it's your codebase, changes are a normal development request, not a renegotiation with a platform vendor. Most changes are scoped and estimated within a day or two of you describing them.

Will we be dependent on you for every tweak?

No — we document the prompt and validation logic clearly enough that a competent developer on your side (or a new vendor) can pick it up.

How do you measure whether the output is actually good enough to ship?

We build an evaluation set from real examples in your workflow before launch, so quality is measured against cases that actually matter to you — not a generic benchmark that doesn't reflect your specific task.

• Related

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Ready to scope this?

Tell us what you want automated — we'll come back with a fixed scope and a quote.

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