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LLM CUSTOMIZATION

Make the model yours — measurably.

Out of the box, every LLM is a generalist. Your product needs a specialist: your tone, your formats, your accuracy bar, your cost ceiling. Dezvo customizes LLMs systematically — prompt engineering with version control, fine-tuning when the data justifies it, eval suites that prove improvement, and guardrails that hold the line in production.

See Our Work
Customization toolkit
  • Versioned prompt engineering
  • Fine-tuning (OpenAI, open-source)
  • Frozen-set evaluation suites
  • Guardrails & output validation
  • Token & latency optimization
PROMPTING VS FINE-TUNING

The decision that saves you months.

Prompt engineering shapes model behaviour through instructions, examples, and output constraints — it's fast, cheap, and reversible, and it solves the large majority of quality problems. Fine-tuning retrains the model's weights on your examples — it's the right tool when you need consistent style at scale, a smaller/cheaper model to match a bigger one's quality on a narrow task, or behaviour prompts can't reach.

The honest sequence is: engineer the prompts, build an eval set, measure — and only fine-tune if the eval says prompting has plateaued. Teams that fine-tune first burn months and training budgets on problems a better prompt would have solved in a week. We always run the eval first.

HOW WE CUSTOMIZE

Four disciplines, one measured pipeline.

Prompt engineering

System prompts, few-shot examples, and output schemas — versioned in git, A/B tested against the eval set, never tweaked blind in a playground.

Fine-tuning

Dataset curation, training, and validation on OpenAI fine-tunes or open-source models (Llama, Mistral) — when evals prove prompting has plateaued.

Evaluation suites

A frozen test set of real cases scored on accuracy, format, tone, and safety — run on every prompt change, model upgrade, and deploy.

Guardrails & optimization

Input/output validation, PII redaction, jailbreak resistance — plus routing, caching, and token diet to cut cost without cutting quality.

FAQ

Common questions, answered.

If your question isn't here, message us — usually same-day reply.

Fine-tune when three things are true: prompting has measurably plateaued on your eval set, you have 500+ high-quality training examples, and the task is narrow and stable (classification, extraction, a fixed style). For everything else — and as the first step always — systematic prompt engineering wins on speed, cost, and reversibility.

OpenAI's GPT models via their fine-tuning API, and open-source models (Llama, Mistral, Qwen) which you then own outright and can self-host. Anthropic's Claude doesn't offer general fine-tuning — for Claude we get equivalent gains through prompt optimization, few-shot curation, and retrieval grounding.

With an eval suite built before we change anything: 100-500 real examples from your domain, scored automatically (exact match, rubric scoring, LLM-as-judge with human calibration). Every change — prompt, model, fine-tune — is a before/after number on that same set. No “it feels better.”

Usually by 40-70%. The levers: route easy cases to smaller models, prompt caching for repeated context, semantic caching for repeated questions, trimming bloated prompts, and fine-tuning a small model to replace a large one on narrow tasks. The eval suite proves quality held while the bill dropped.
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