EconML is a Python library for estimating heterogeneous treatment effects (CATE) from observational and experimental data using machine learning. It implements state-of-the-art causal inference methods including Double/Debiased Machine Learning (DML), Generalized Random Forests (GRF), Orthogonal Random Forests, Doubly Robust Learners, Instrumental Variable estimators (DMLIV, DRIV, OrthoIV), and Meta-Learners (S, T, X, DA). The library provides a unified scikit-learn-compatible API across all estimators with fit, effect, marginal_effect, and inference methods (confidence intervals, p-values). It includes advanced features such as cross-fitting, sample weights, missing data support, federated learning, sensitivity analysis, and model selection via RScorer. The repository also contains extensive documentation, notebooks, Monte Carlo tests, and a Cython-optimized tree implementation for performance.
OpenBB is an open-source financial data platform that provides a unified, multi-interface access layer to over 20 data providers (FMP, FRED, CBOE, Yahoo Finance, Intrinio, etc.) through a modular provider-extension architecture. The core library (`openbb_core`) defines a standardized Fetcher pattern (transform_query -> extract_data -> transform_data), Pydantic-based standard models for equities, derivatives, fixed income, economics, and more, and a command routing system exposed via a Python SDK (OBBject), a REST API (FastAPI), a CLI (argparse translator), a desktop app (Tauri + React), and an MCP (Model Context Protocol) server for AI agents. The platform includes domain-specific extensions (equity, crypto, economy, quantitative, technical analysis, charting) and a cookiecutter template for scaffolding new providers or OBBject extensions. While the codebase is large and actively maintained, there is notable technical drift in the form of hardcoded API URLs, mixed sync/async extraction, deprecated endpoints, and code duplication across many provider implementations. The charting extension's plugin-based technical indicator system, the country/exchange validation utilities, and the LRU cache with TTL are high-craftsmanship, reusable components that demonstrate non-obvious software engineering skill.