# cognitect/transit-format

A data interchange format.

Repository: https://github.com/cognitect/transit-format
Canonical: https://ross.abutalabs.com/products/transit-format
Language: Clojure
License Family: other
Last push: 2026-02-24T15:12:46+00:00

## Health v2 (maintenance only)
Score: 63/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 69, release rhythm 35, longevity 100
- inputs: {"age_days": 4451, "days_push": 190, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1918, forks 37 (observed 2026-08-28T04:05:54.877436+00:00)

## What it is
Transit is a data interchange format and set of libraries for conveying typed values between applications written in different programming languages, built on top of JSON and MessagePack. It uses a tag-based extension mechanism so values like dates and URIs can be represented without schemas, while remaining self-describing and compressible via caching of repeated elements.

## Use cases
- send typed values between services in different languages
- serialize dates and URIs over JSON without losing type info
- reduce payload size by caching repeated map keys
- stream values between programs without a top-level envelope
- exchange data between Clojure and JavaScript applications
- decode and inspect messages from apps using unknown extension tags

## When to choose
- you need typed, self-describing data interchange across languages
- you want JSON or MessagePack compatibility with richer semantic types
- you need streaming-friendly encoding without schemas
- you work in the Clojure ecosystem where Transit is well supported

## When to avoid
- human readability of payloads is a priority
- you need schema validation or a formal type system
- you need object identity or reference semantics in serialized data
- your consumers only support plain JSON with no Transit-aware readers

## Facets
- artifact type: library
- maturity: stable
- function: serialization
- domain: developer-tools, apis, microservices
- platform: cross-platform, jvm, python
- tags: data-interchange-format, messagepack, typed-values, specification, clojure, javascript

## Member repositories
- cognitect/transit-format (main) score 63

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:54.877436+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 2026-08-30T03:09:59.885568+00:00, confidence not recorded.
  - readme: https://github.com/cognitect/transit-format (fetched 2026-08-28T04:05:54.877436+00:00, sha 5ea0757ad135)
- Data as of 2026-08-30T08:39:29.467469+00:00.