---
title: "I Will Build a Custom AI Application with Python, OpenAI & LangChain"
url: https://zinnhub.com/zinns/develop-custom-ai-applications-using-python-openai-chatgpt-langchain/
description: "Get a production-ready AI application built by a senior engineer — from a simple ChatGPT integration right through to a fully orchestrated LLM solution with RAG pipelines, custom actions, and conversation starters."
published: 2025-11-18T03:33:53+00:00
modified: 2026-10-19T17:26:03+00:00
language: en-GB
---

# I Will Build a Custom AI Application with Python, OpenAI & LangChain

If you need an AI application that actually works in the real world — not just a proof of concept — you are in the right place.

Zinn Digital® is a London-based AI and backend engineering studio specialising in end-to-end AI development. Whether you need a straightforward ChatGPT-powered automation, a retrieval-augmented generation (RAG) pipeline that searches your own data, or a fully featured AI assistant with conversation starters and custom actions, this service covers the full spectrum.

\*\*What you get\*\*

Every engagement delivers a functional, tested Python application built on the latest AI tooling. The entry tier gives you a clean, working custom GPT application — ideal for automating a specific task or validating an AI use case quickly. Step up to the Standard tier and your application gains conversation starters and a more polished interactive experience, along with a longer delivery window for a more considered build. The Full Build tier adds custom actions, giving your AI assistant the ability to call external services, APIs, or internal tools — transforming it from a chat interface into an autonomous agent.

Optional bolt-ons let you layer in DALL·E image generation or a code interpreter capability without committing to a larger tier.

\*\*How it works\*\*

1. Place your order and complete the brief — tell us what your application needs to do, the data or context it should work with, and any integration points.
 2. Our engineering team designs the architecture and begins development.
 3. You receive the working application via the order manager, with source code and clear documentation.
 4. Raise revision requests through the order chat and we will address them within the agreed scope.

\*\*Our technical stack\*\*

We build with Python, FastAPI, LangChain, LlamaIndex, OpenAI, Anthropic, Gemini, Pinecone, Chroma, [Next.js, React](https://zinnhub.com/zinns/develop-modern-full-stack-web-apps-using-next-js-react-and-ai-integrations/), and Tailwind — selecting the right combination for your specific requirements. For AI orchestration we draw on RAG pipelines, LLM integration, prompt engineering, and where needed, custom model fine-tuning using Transformers, LoRA, and PEFT.

\*\*Who this is for\*\*

This service suits founders and product teams who want to ship an AI feature without hiring a full-time engineer, technical leads who need a reliable delivery partner for an AI workstream, and businesses that want to automate knowledge-intensive tasks using their own data and workflows.

Zinn Digital® combines rigorous backend engineering with deep LLM expertise — built and delivered from London, England.