LLM Tech Stack & Model Ecosystem

APIs, foundation models, embeddings, open vs closed systems, and infrastructure choices.

Overview

Modern LLM applications rely on a layered tech stack involving APIs, foundation models, embedding systems, and the infrastructure running them. Developers must choose between open and closed models, weigh hosting options, and design the pipeline supporting inference, fine‑tuning, vector search, and integration.

Key Concepts

APIs

Access models via hosted providers like OpenAI, Anthropic, Google, and others.

Foundation Models

Large pretrained models forming the base of modern AI capabilities.

Embeddings

Vector representations powering semantic search, retrieval, and classification.

Open Models

Self‑hostable and fine‑tunable models like Llama, Mistral, DeepSeek.

Closed Models

Proprietary, highly capable models available via API only.

Infrastructure

Options include cloud GPU clusters, managed inference endpoints, and on‑device execution.

LLM System Process

1. Input

User query or structured data.

2. Embedding / Retrieval

Semantic search and context building.

3. Model Inference

Open or closed LLM generates output.

4. Output

Response, action, or downstream pipeline.

Use Cases

RAG Systems

Knowledge retrieval enriched with embeddings.

Agentic Workflows

Autonomous tools orchestrating tasks.

Custom AI Apps

Domain‑specific assistants and automation.

Open vs Closed Models

Open Models

  • Fine‑tuning flexibility
  • Self‑hosting control
  • Lower cost at scale

Closed Models

  • State‑of‑the‑art capabilities
  • Fully managed infrastructure
  • Zero maintenance

FAQ

Which type of model should I choose?

Closed models for quality; open models for customization and scale.

Do I need embeddings?

Yes for retrieval‑augmented systems, search, and long‑context tasks.

Should I self‑host?

Only if you need privacy, control, or lower cost at large volumes.

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