# foxglove/mcap

MCAP is a modular, performant, and serialization-agnostic container file format, useful for pub/sub and robotics applications.

Repository: https://github.com/foxglove/mcap
Canonical: https://ross.abutalabs.com/products/mcap
Homepage: https://mcap.dev
Language: Rust
License: MIT
License Family: permissive
Topics: robotics, data, serialization, deserialization, typescript, golang, python, cpp, swift
Last push: 2026-09-02T19:00:28+00:00

## Health v2 (maintenance only)
Score: 98/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 100, release rhythm 93, longevity 100
- inputs: {"age_days": 1748, "days_push": 0, "days_rel": 49, "gap_med": 5, "n_releases_24m": 52}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1071, forks 224 (observed 2026-09-03T02:15:12.079294+00:00)

## What it is
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
- artifact type: library
- maturity: stable
- function: serialization, logging, file-system, cli
- domain: robotics, files, developer-tools
- platform: cross-platform, cpp, go, python, rust, cli
- tags: container-file-format, pub-sub-logging, multimodal-log-data, ros2, sensor-data, message-schemas, lz4, zstd, data-engineering, swift, nodejs

## Member repositories
- foxglove/mcap (main) score 98

## Provenance
- Observed fields: from GitHub, fetched 2026-09-03T02:15:12.079294+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:58:22.934403+00:00, confidence not recorded.
  - readme: https://github.com/foxglove/mcap (fetched 2026-09-03T02:15:12.079294+00:00, sha 3b590fe3e802)
  - homepage: https://mcap.dev (fetched 2026-08-29T12:59:51.293807+00:00, sha c4fca5726c03)
  - registry_crates: https://crates.io/api/v1/crates/mcap (fetched 2026-08-29T12:59:51.297333+00:00, sha 44c82f7ff6ec)
- Data as of 2026-08-30T08:39:29.467469+00:00.