foxglove/mcap

Health v2 · maintenance only

Adoption not part of the score

1071 stars · 224 forks observed · 2026-09-03

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

MCAP is an open-source, serialization-agnostic container file format for multimodal log data, with native reader/writer libraries in C++, Go, Python, Rust, Swift, and TypeScript. It is designed for pub/sub and robotics workloads, featuring append-only writes, optional indexing, and LZ4/Zstandard compression, and is the default log format in ROS 2.

Use cases

• log pub/sub messages and sensor data to a file
• record and replay robotics messages in ROS 2
• store timestamped multimodal log data with schemas
• read and write MCAP files in Python or C++
• merge, split, and inspect robot log files from the CLI
• stream indexed log data over low-bandwidth connections

When to choose

• you need a production-grade log format for robotics or autonomous vehicle data
• you want serialization-agnostic storage of pre-serialized messages like Protobuf, ROS, or CDR
• you need efficient indexed reads and crash-resilient append-only writes
• you need native libraries across multiple languages

When to avoid

• you only need simple structured data files like CSV or JSON
• your use case is general-purpose analytics rather than timestamped message logging
• you need a time-series database with query capabilities rather than a file format

Facets

library · maturity stable

serialization logging file-system cli robotics files developer-tools cross-platform cpp go python rust cli container-file-format pub-sub-logging multimodal-log-data ros2 sensor-data message-schemas lz4 zstd data-engineering swift nodejs

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