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.
I Will Build a Custom AI Application with Python, OpenAI & LangChain
A clean, functional custom GPT application built with Python and OpenAI — ideal for automating a focused task.
- Functional custom GPT application
- Python & OpenAI / ChatGPT integration
- Automated task handling
- Delivered with source code
- Unlimited revisions
A more complete AI assistant with conversation starters and a carefully engineered user experience.
- Everything in Starter
- Conversation starters configured
- Web browsing capability enabled
- Prompt engineering & optimisation
- 1 revision included
- Delivered with source code and documentation
A production-ready AI application with custom actions, enabling your assistant to call APIs and external tools autonomously.
- Everything in Standard
- Custom actions — connect to external APIs or internal tools
- AI gateway architecture & orchestration
- Advanced LLM integration (OpenAI, Anthropic, Gemini or Ollama)
- Scalable backend built with FastAPI or Flask
- Delivered with full source code, documentation, and deployment guidance
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Value Position
AI Stack Depth
Multi-Model Support
Production-Ready Backend
Base Entry Point
What You'll Receive
Full Description
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, 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.
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Compare Packages
| Feature | Starter | Standard | Full Build |
|---|---|---|---|
| Delivery Time | 3 days | 5 days | 10 days |
| Revisions | unlimited | 1 | 1 |
| Functional custom GPT application | ✓ | ✕ | ✕ |
| Python & OpenAI / ChatGPT integration | ✓ | ✕ | ✕ |
| Automated task handling | ✓ | ✕ | ✕ |
| Delivered with source code | ✓ | ✕ | ✕ |
| Unlimited revisions | ✓ | ✕ | ✕ |
| Everything in Starter | ✕ | ✓ | ✕ |
| Conversation starters configured | ✕ | ✓ | ✕ |
| Web browsing capability enabled | ✕ | ✓ | ✕ |
| Prompt engineering & optimisation | ✕ | ✓ | ✕ |
| 1 revision included | ✕ | ✓ | ✕ |
| Delivered with source code and documentation | ✕ | ✓ | ✕ |
| Everything in Standard | ✕ | ✕ | ✓ |
| Custom actions — connect to external APIs or internal tools | ✕ | ✕ | ✓ |
| AI gateway architecture & orchestration | ✕ | ✕ | ✓ |
| Advanced LLM integration (OpenAI, Anthropic, Gemini or Ollama) | ✕ | ✕ | ✓ |
| Scalable backend built with FastAPI or Flask | ✕ | ✕ | ✓ |
| Delivered with full source code, documentation, and deployment guidance | ✕ | ✕ | ✓ |
Extra Information
Why Choose Me
Tools I Use
Perfect For
Frequently Asked Questions
Please share a clear description of what you want the AI application to do, any relevant data sources or documents it should work with, any APIs or external services it should connect to, and your preferred programming environment if you have one. The more context you provide, the faster we can begin.
We work across OpenAI (GPT-4 and later), Anthropic (Claude), Google Gemini, and Ollama for local models. On the orchestration side we use LangChain and LlamaIndex. Vector stores include Pinecone and Chroma. Backend services are built with Python, FastAPI, and Flask.
The Starter tier delivers a straightforward custom GPT application for a focused automated task. The Standard tier adds conversation starters and web browsing capability for a richer assistant experience. The Full Build tier introduces custom actions, allowing the assistant to call external APIs and services — making it a true agent rather than a chat interface.
Custom actions allow your AI assistant to interact with external systems — for example, retrieving live data from an API, writing records to a database, or triggering a workflow in another tool. We design and implement these integrations as part of the Full Build.
Yes. Both are available as optional add-ons that can be attached to any tier at checkout. They are bolt-on capabilities rather than core features of the tiered packages.
The Starter tier includes unlimited revisions. Standard and Full Build each include one revision round. Additional revision rounds can be purchased as an add-on. All revision requests should be submitted clearly through the order chat so we can address them efficiently.
Yes. Every tier delivers the complete source code for the application, giving you full ownership of what is built. The Standard and Full Build tiers also include documentation to help you or your team maintain and extend the application going forward.
Customer Reviews
See what our customers say about this Zinn
Neil has been a great teammate to work with on this project. The scope evolved over time, and he adapted quickly while continuing to put in strong effort and thoughtful work throughout. He’s diligent, responsive, and committed to getting things right. I appreciate his flexibility and professionalism, and I’m looking forward to continuing to work with him on future phases and projects.
Neil delivered exceptional backend development work for CorpusIQ. From the beginning, his communication was clear, structured, and proactive. He translated complex requirements into a clean and scalable architecture that worked flawlessly. The quality of his code was outstanding. He built efficient APIs, documented every endpoint, and designed robust database logic that integrated perfectly with our front-end and automation systems. Authentication, data models, and error handling were implemented with precision and a strong focus on maintainability. Neil consistently went beyond what was expected.
Delivers consistently high-quality work and code, clearly demonstrating deep expertise and a strong command of his craft.
Neil has done outstanding work on the CorpusIQ codebase. The implementation is clean, structured and production-focused, with strong attention to security, scalability and long-term maintainability. He consistently delivers high-quality work, thinks through edge cases and executes with precision.
Great experience working with Neil. He delivered a solid backend foundation, communicated clearly throughout, and was proactive in sharing updates and technical explanations. The work was well-structured and met the scope we agreed on. Looking forward to continuing the project together.
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