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NextGen Code

AI Strategy & Implementation

Custom AI development: AI built on your data and tested before it ships

Custom AI development is for businesses whose problem doesn't fit an off-the-shelf tool: an assistant that answers from your own documents, an AI feature inside your product, or a system that reads images and paperwork no generic app understands. NextGen Code designs, builds, and runs these systems for small and mid-sized businesses and SaaS companies, from first prototype to production.

This is for you if…

  • Your team spends hours digging through manuals, contracts, SOPs, or past projects for answers buried in documents.
  • Customers are asking when your product will have AI features, and you want them built properly, not bolted on.
  • Off-the-shelf AI tools can't see your systems, don't follow your rules, or can't meet your data requirements.
  • You have a prototype that demos well but gives wrong answers too often to put in front of customers.
  • Your AI usage bills are growing faster than the value, or responses are too slow for people to wait on.
  • You process scans, forms, or photos that generic optical character recognition (OCR) tools keep getting wrong.

Overview

LLM apps, RAG, copilots, document AI, and computer vision, built and tested like production software.

Our team has shipped production software since 2018, including the computer-vision receipt parser inside DIVIT, an iOS and Android bill-splitting app. That background matters, because most of the work in an AI application isn't the model. It's the data pipeline, integrations, user experience, security, and the tests that show it works.

We choose models on evidence. We test hosted large language models (LLMs) from OpenAI, Anthropic, and Google alongside open-weight models, which you can download and run on your own servers, then pick on accuracy, cost, speed, and where your data is allowed to go. We fine-tune, meaning further train a model on your examples, only when testing shows that better prompts and retrieval can't close the gap.

What you get

Deliverables, not decks.

  • 01

    Technical design and model selection

    Architecture, data flow, and a model shortlist tested on your real examples, with the expected accuracy, cost per request, and response time of each option written down before we build.

  • 02

    Production AI application

    An LLM application, copilot, AI feature, or RAG system (retrieval-augmented generation, which lets an AI answer from your own documents), integrated with your systems and interface, with sign-in, user permissions, and audit logs built in.

  • 03

    Evaluation suite

    Evals are automated tests that score an AI system's answers. We build yours from real questions and documents, grade accuracy, grounding in your sources, and safety, and run them before every release to catch quality drops early.

  • 04

    Guardrails and security controls

    Input and output checks, defenses against prompt injection (hidden instructions that try to hijack the AI), retrieval limited to what each user may see, redaction of sensitive fields, and spend limits, designed against the OWASP Top 10 for LLM Applications.

  • 05

    Cost and speed tuning

    Model routing, caching, shorter prompts and context, and batch processing where it fits, tuned to agreed targets for cost per request and response time.

  • 06

    Code, documentation, and handoff

    Source code in your repository, architecture notes, runbooks, and the latest eval report, so your team or ours can maintain and extend the system.

How it works

A clear process, start to finish.

  1. 011–2 weeks

    Discovery and feasibility

    We define the job the AI must do, gather real examples, set targets for accuracy, cost, and speed, and test candidate models and approaches on your data.

  2. 022–4 weeks

    Prototype

    A working prototype in front of real users, scored against the eval set, so the decision to go further rests on evidence rather than a demo.

  3. 034–12 weeks

    Production build

    We harden the system in 2-week cycles: integrations, permissions, guardrails, monitoring, and interface, with the eval suite running on every change.

  4. 04Ongoing

    Launch and operate

    A staged rollout, monitoring of usage, cost, and quality, review of flagged answers, and a full re-test whenever a model, prompt, or data source changes.

What we measure

The numbers this moves.

We baseline these before we start and report against them after launch.

  • Answer accuracy

    Scored on your eval set before launch and sampled every week after, against a target we agree on up front for each type of question.

  • Time to find an answer

    Minutes staff or customers spend finding information or finishing a task, measured before and after. Example: 25 lookups a day × 6 minutes each is 2.5 hours a day to win back.

  • Cost per request

    Model, hosting, and search costs per answer or document, tracked against a target so usage can grow without the bill outgrowing the value.

  • Response time

    Seconds from question to answer, which often decides whether people use the tool at all. We set a target for each feature and tune to it.

  • Adoption and deflection

    Weekly active users for internal tools, or the share of customer questions resolved without a support ticket for customer-facing ones.

In practice

What this looks like in a real business.

  • RAG over company documents

    Example: field technicians at a manufacturer ask questions in plain English and get answers drawn from service manuals and past work orders, each with a citation to the exact page, so they can check the source before acting on it.

  • Internal copilot

    Example: an accounting firm's assistant drafts client memos from past work and pulls figures from its practice-management system through MCP (Model Context Protocol, an open standard for connecting AI to business tools), opening only files the person asking may see.

  • AI features inside a SaaS product

    Natural-language search, automatic summaries, smart form filling, and in-app assistants added to an existing product, with each customer's data kept separate and usage-based cost controls per account.

  • Document intelligence and OCR

    Structured data pulled from scanned forms, contracts, lab reports, or handwritten notes, using OCR to read the text and a language model to understand it, with low-confidence fields sent to a person for review.

  • Computer vision

    Reading receipts, labels, gauges, damage photos, or product images. DIVIT is one we built: its receipt parser reads line items, subtotal, and tax from a photo so a group can split the bill and request payment through Venmo.

  • Customer-facing assistant

    Example: a property manager's resident assistant answers lease and maintenance questions from the actual lease and house rules, opens work orders, and hands anything legal or urgent to staff.

Tools & platforms we work with

  • OpenAI API
  • Claude API
  • Gemini API
  • Amazon Bedrock
  • Google Vertex AI
  • Microsoft Foundry
  • Llama
  • Mistral
  • Hugging Face
  • PostgreSQL with pgvector
  • LangChain
  • Model Context Protocol (MCP)
  • Google Document AI
  • OpenCV

We're vendor-neutral: we recommend what fits your stack, budget and risk profile — not what pays us a referral fee.

Next step

Let's talk about Custom AI.

Bring a problem or a goal. In 30 minutes we'll tell you what's realistic, what it would take, and where AI fits — even if the answer is to start smaller.

FAQ

Custom AI: common questions

Still have a question? Ask us directly.

How much does custom AI development cost?

Budget for two things: the build and the running costs. The build is driven by how many systems the AI connects to, how much data must be cleaned and indexed, how high the accuracy bar is, how polished the interface needs to be, and your compliance requirements. Running costs scale with usage: model fees per request, hosting, and search infrastructure. We estimate both during discovery, test cheaper models wherever they meet the accuracy target, and set spend limits so monthly costs stay predictable.

How long does it take to build a custom AI application?

A focused prototype typically takes 2–4 weeks, and a production system 2–4 months, depending on integrations, data preparation, and the accuracy bar. Discovery comes first, usually 1–2 weeks, to test whether the idea works on your data at all. After that, every 2-week cycle ends with a demo, so you can stop, adjust, or expand based on real results instead of a long specification.

Will our data be used to train AI models?

Not when the system is built on business-grade services. The paid APIs from OpenAI, Anthropic, Google, AWS, and Microsoft exclude your inputs and outputs from model training by default, and some offer limited or zero data retention for eligible uses. When data can't leave your environment, we deploy open-weight models in your own cloud account or on your own servers. Either way, the system retrieves only the documents the person asking is already allowed to see.

Do we need to fine-tune a model?

Usually not. Most business applications get better results, sooner and for less money, from clear instructions, retrieval over your documents, and well-designed tools. Fine-tuning earns its place when you need a consistent format or tone at high volume, or a smaller, cheaper model to match a larger one on a narrow task. We decide with evals: if a fine-tuned model doesn't beat the baseline on your test set, it doesn't ship.

Should we use a hosted model or an open-weight model?

Start with whatever meets your accuracy target at the lowest total cost and risk. Hosted models from OpenAI, Anthropic, and Google are usually the most capable and the fastest way to launch. Open-weight models you run yourself give you more control over data, vendor lock-in, and cost at very high volume, but you take on hosting and upkeep. Many systems use both, and we design so you can switch models without a rewrite.

How do you know the AI's answers are accurate?

We measure it. Before building, we assemble an evaluation set of real questions or documents from your business with known correct answers. Every version of the system is scored against it for accuracy, grounding in your sources, and safe behavior, and we agree on the passing bar with you before launch. After launch, we sample live answers, collect user feedback, and add each failure to the test set so a repeat gets caught.

What happens after launch?

An AI system needs operating, not just hosting. Models get updated or retired, your documents change, and users ask questions nobody predicted. We monitor accuracy, cost, and response times, re-run the eval suite whenever a model or prompt changes, and review flagged answers. You can keep us on a support plan, or we hand over the code, documentation, and evals so your own team can run it.