How to Choose an LLM Development Company: Checklist and 12 Questions

What types of LLM development work are there?

LLM development work falls into four types: integration (adding an LLM to an existing app through an API), retrieval-augmented generation or RAG (answering from your own documents), fine-tuning (adapting a model to a style or task), and agents (LLMs that use tools and take actions). Most business projects are integration or RAG.

What should an LLM company’s evaluation process look like?

A good LLM company builds a test set of real questions or tasks from your business, defines what a correct answer looks like, and measures the system against it before launch and after every change. Without evaluations, nobody knows whether a new prompt or model made things better or worse.

Ask to see an example evaluation report from a past project, with the data anonymised. It tells you more than any demo.

What 12 questions should you ask an LLM development company?

Ask questions that reveal real production experience: how data is handled, how quality is tested, how costs are controlled and what happens after launch. Experienced teams answer specifically and mention trade-offs; inexperienced teams answer in generalities.

• 1. Which LLM projects have you shipped to production, and can I speak to a client?
• 2. Would you use integration, RAG, fine-tuning or an agent for my case, and why?
• 3. Where will my data go, and is it used to train any model?
• 4. How will you measure answer quality before launch?
• 5. How do you prevent and detect hallucinations?
• 6. How do you defend against prompt injection?
• 7. Can we switch model provider later without a rebuild?
• 8. What will it cost per month to run at our expected volume?
• 9. How do you monitor the system after launch?
• 10. Who owns the code, prompts and evaluation data?
• 11. What does a small pilot look like, and how do we judge success?
• 12. What support and updates do you offer after launch?

How do LLM development companies price their work?

LLM development companies price work as a fixed-price project, a time-and-materials contract or a monthly retainer. Fixed price suits well-defined integrations; time and materials suits exploratory RAG or agent work; retainers suit ongoing improvement. Running costs for model usage and hosting are billed separately.

At WebsNexus, LLM integration starts from $400 and custom LLM development from $2,000. Our custom LLM development cost guide explains what drives the price.

What are the red flags when hiring for LLM work?

The biggest red flags are promising perfect accuracy, recommending fine-tuning or a custom model before trying simpler options, having no evaluation process, and not discussing running costs. Also be wary of teams that cannot explain where your data goes or how they handle prompt injection.

Should you start with a pilot?

Yes. A short, paid pilot on one real use case shows how the team works and whether the approach is accurate enough before you commit to a full build. Agree on success measures first, such as the share of test questions answered correctly or hours saved per week.