PyOD vs PySAD

PyOD is a free Python library for anomaly detection, with documented detectors for tabular, time-series, graph, text, image, and audio data. Its documentation lists 61 detectors available through a common API. Users can work with the classic detector API or ADEngine, which profiles data, selects benchmark-backed detectors, runs multiple detectors in parallel, computes consensus scores, and reports diagnostics. ADEngine also works as a standalone Python API without an LLM. PyOD includes an agentic investigation workflow and activation paths for Claude Code, Codex, and MCP-compatible agents, including an od-expert skill and optional MCP server. Installation is available through pip, conda-forge, or source, and requires Python 3.9 or higher. Optional pip extras enable capabilities including PyTorch, graph detectors, embeddings, audio, and MCP support. The project serves academic research and commercial products. Its model persistence guidance warns that pickle and joblib can execute arbitrary Python code during deserialization, requiring callers to pass trusted=True when loading artifacts. ADEngine describes its quality verdict as a heuristic rather than a guarantee and recommends validation against held-out labels or domain review.

PySAD is a free, open-source Python framework for online anomaly detection in streaming data. Its models update when each new data instance arrives, supporting sequential detection for univariate and multivariate data. The project describes 16 online detectors, including xStream, LODA, RS-Hash, Half-Space Trees, and Robust Random Cut Forest. It also provides stream simulators, evaluators, preprocessors, statistic trackers, postprocessors, and probability calibrators. Integrations allow batch anomaly detectors from PyOD to run in a streaming setting. Experiments can use supervised, semi-supervised, or unsupervised settings. The documentation says streaming methods may retain one instance or a small recent window to meet memory and processing constraints. Installation is available through pip or the GitHub source; the current README lists Python 3.10 or newer on Linux, macOS, and Windows. PySAD is self-hosted and distributed under a BSD 3-Clause license. Its plan costs nothing, and 17 labelled benchmark datasets are downloaded on first use.