Reference · 46 tools
Tools
The platforms and libraries the lessons use, what each one is for, and whether you can start for free. Pricing changes often. These notes were checked in November 2026, so confirm on the official page before you rely on them.
Model APIs
Claude API (Anthropic)
Paid API, per tokenClaude models (Haiku, Sonnet, Opus) through the Messages API, with tool use, prompt caching and batches.
Official docs for Claude API (Anthropic)Lesson: Calling an LLM API for the first timeLesson: Prompt caching and token pricingLesson: Function and tool calling basics
OpenAI API
Paid API, per tokenGPT models through the Responses API, plus embeddings, batch and moderation endpoints.
Official docs for OpenAI APILesson: Calling an LLM API for the first timeLesson: Embeddings and cosine similarity
Gemini API (Google)
Free tier + paid APIGoogle's Gemini models for text, images, audio and video.
Official docs for Gemini API (Google)Lesson: Calling an LLM API for the first timeLesson: Multimodal inputs
Hugging Face Hub
Free + paid plansThe main hub for open models, datasets and demo apps (Spaces), with hosted inference options.
Official docs for Hugging Face HubLesson: Open vs closed models, small vs largeLesson: Serverless functions and the easy hosting route
Local and self-hosted models
Ollama
Open source (MIT)Run open models on your own laptop or server with one command and a local HTTP API.
Official docs for OllamaLesson: Ollama for local modelsLesson: Open vs closed models, small vs large
vLLM
Open source (Apache 2.0)High-throughput serving engine for LLMs with PagedAttention, continuous batching and an OpenAI-compatible API.
Official docs for vLLMLesson: Serving models with vLLMLesson: GPU instances
LiteLLM
Open source + enterprise planOne Python interface and proxy for 100+ model providers, with routing, fallbacks and cost tracking.
Official docs for LiteLLMLesson: Model routing, fallbacks and LLM gateways
Classic ML and data
scikit-learn
Open source (BSD)The standard Python library for classic machine learning (regression, trees, clustering, metrics).
Official docs for scikit-learnLesson: Classic machine learning in one lessonLesson: Overfitting and train, validation and test splits
NumPy
Open source (BSD)Fast arrays and maths in Python; the base of almost every AI library.
Official docs for NumPyLesson: Vectors and matrices, just enough for AILesson: Python for AI engineers
pandas
Open source (BSD)Tables (DataFrames) for loading, cleaning and analysing data in Python.
tiktoken
Open source (MIT)OpenAI's fast tokenizer library, handy for counting tokens.
PEFT (Hugging Face)
Open source (Apache 2.0)Parameter-efficient fine-tuning methods such as LoRA and QLoRA.
Official docs for PEFT (Hugging Face)Lesson: Fine-tuning with LoRA and QLoRA
RAG and vector search
pgvector
Open source (PostgreSQL licence)Vector similarity search inside Postgres, with HNSW and IVFFlat indexes.
Official docs for pgvectorLesson: Vector databases, HNSW and pgvectorLesson: Access control in RAG
Qdrant
Open source + managed cloudA dedicated vector database with filtering, hybrid search and a managed cloud.
Official docs for QdrantLesson: Vector databases, HNSW and pgvector
Pinecone
Free tier + paidA fully managed vector database.
Official docs for PineconeLesson: Vector databases, HNSW and pgvector
Chroma
Open source + managed cloudA simple embedded vector store popular for prototypes.
Official docs for ChromaLesson: Vector databases, HNSW and pgvector
rank-bm25
Open source (Apache 2.0)A small Python implementation of BM25 keyword ranking.
Official docs for rank-bm25Lesson: BM25 keyword search and hybrid searchLesson: Capstone: build a small RAG app from scratch
Unstructured
Open source + paid APIParses PDFs, Office files, HTML and images into clean text and elements for ingestion.
Official docs for UnstructuredLesson: Document parsing and ingestion pipelines
Agents and protocols
Model Context Protocol
Open standard, open-source SDKsAn open protocol for connecting AI apps to tools and data through MCP servers.
Official docs for Model Context ProtocolLesson: MCP: servers and clientsLesson: MCP server trust
LangGraph
Open source (MIT) + paid platformA library for building stateful agent workflows as graphs, with checkpoints and human-in-the-loop.
Official docs for LangGraphLesson: LangGraph, state and checkpointsLesson: Human in the loop
OpenAI Agents SDK
Open source (MIT)A lightweight Python framework for agents with tools, handoffs, guardrails and tracing.
Official docs for OpenAI Agents SDKLesson: The OpenAI Agents SDK and other frameworks
Agent2Agent (A2A) protocol
Open standardAn open protocol for agents from different vendors to discover each other and exchange tasks.
Official docs for Agent2Agent (A2A) protocolLesson: The A2A protocol
Evals and observability
Langfuse
Open source + managed cloudOpen-source LLM tracing, prompt management, evals and cost tracking.
Official docs for LangfuseLesson: Langfuse and observability dashboardsLesson: Tracing and OpenTelemetry for LLMsLesson: Prompt versioning, model versioning and registries
Ragas
Open source (Apache 2.0)Metrics for evaluating RAG pipelines, such as faithfulness and context precision.
Official docs for RagasLesson: RAG evals: faithfulness, relevance and context precisionLesson: Eval tools at a glance
DeepEval
Open source + paid platformA pytest-style framework for LLM evals with many built-in metrics.
Official docs for DeepEvalLesson: Eval tools at a glanceLesson: Regression evals in CI and A/B testing prompts
promptfoo
Open source + enterpriseConfig-driven evals and red teaming for prompts and models, runnable in CI.
Official docs for promptfooLesson: Eval tools at a glanceLesson: Red teaming
OpenTelemetry
Open sourceThe open standard for traces, metrics and logs, including GenAI semantic conventions.
Official docs for OpenTelemetryLesson: Tracing and OpenTelemetry for LLMsLesson: Logging and monitoring
Security
Llama Guard and Prompt Guard
Open weights (Llama licence)Meta's open classifier models for unsafe content (Llama Guard) and prompt injection or jailbreaks (Prompt Guard).
Official docs for Llama Guard and Prompt GuardLesson: Input guardrails, output validation and moderationLesson: Prompt injection, indirect injection and jailbreaks
Presidio
Open source (MIT)Detects and anonymises personal data (PII) in text and images.
Official docs for PresidioLesson: PII redaction and data leakage
OWASP GenAI Security Project
FreePublishes the Top 10 for LLM applications and for agentic applications, plus guides.
Official docs for OWASP GenAI Security ProjectLesson: The OWASP Top 10 for LLM apps
garak
Open source (Apache 2.0)An LLM vulnerability scanner that probes models for jailbreaks, leaks and other failures.
PyRIT
Open source (MIT)Microsoft's toolkit for automated red teaming of generative AI systems.
gitleaks
Open source (MIT)Scans git repositories and commits for leaked secrets such as API keys.
Official docs for gitleaksLesson: Secrets management and API key rotation
Backend
FastAPI
Open source (MIT)A Python web framework with type-hint validation and automatic OpenAPI docs.
Official docs for FastAPILesson: REST APIs with FastAPILesson: Capstone: build a small RAG app from scratch
Pydantic
Open source (MIT)Data validation with Python type hints, plus Pydantic Settings for configuration.
Official docs for PydanticLesson: Input validation with Pydantic, and configLesson: Structured outputs
PostgreSQL
Open sourceThe popular open-source relational database; with pgvector it also stores embeddings.
Official docs for PostgreSQLLesson: SQL vs NoSQL, indexing and transactions
Redis
Open source + managed cloudAn in-memory store for caching, rate limits, sessions and queues.
Official docs for RedisLesson: Caching with RedisLesson: Rate limiting
Celery
Open source (BSD)A widely used Python task queue for background jobs.
Official docs for CeleryLesson: Message queues and background jobs
pytest
Open source (MIT)Python's most popular testing framework.
Amazon S3
Paid, per GB and requestObject storage for files, with presigned URLs and event notifications.
Deployment
Git
Open sourceVersion control for code, prompts and configuration.
GitHub Actions
Free minutes + paidCI/CD workflows that run on every push and pull request.
Official docs for GitHub ActionsLesson: GitHub ActionsLesson: CI/CD pipelinesLesson: Eval gates in CI
Docker
Free for personal use + paid plansPackages an app and its dependencies into a container image that runs the same everywhere.
Official docs for DockerLesson: DockerLesson: Docker Compose
Kubernetes
Open source; managed versions are paidRuns and scales containers across many machines, with health checks and rolling updates.
Official docs for KubernetesLesson: Kubernetes basicsLesson: Autoscaling and load balancing
OpenTofu / Terraform
Open source (OpenTofu); Terraform has its own licenceInfrastructure as code tools that create and update cloud resources from configuration files.
Official docs for OpenTofu / TerraformLesson: Infrastructure as code
Prometheus and Grafana
Open source + managed cloudMetrics collection, dashboards and alerting.
Official docs for Prometheus and GrafanaLesson: Alerts and dashboards